back to indexEffects of Fasting & Time Restricted Eating on Fat Loss & Health | Huberman Lab Podcast #41
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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we're talking all about fasting.
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And anytime we're talking about fasting,
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we are also talking about eating
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because we all need to eat sooner or later.
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We're going to talk about how fasting and when we eat
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influences a large range of aspects of our health
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and wellbeing, both physical and mental.
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So while nowadays,
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most people are familiar with the term intermittent fasting,
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also sometimes called time-restricted feeding,
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I think most people don't really understand
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how that process works.
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It's sort of obvious that intermittent fasting,
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AKA time-restricted feeding,
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involves eating at certain periods of each 24-hour cycle,
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or maybe even not eating for entire days in some cases.
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But if you think about it, everybody sleeps eventually.
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And therefore, because people don't eat during their sleep,
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almost everybody is employing some form
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of intermittent fasting or time-restricted feeding.
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What we're going to talk about today
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is how particular schedules of time-restricted feeding
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can impact our health in different ways.
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And when I say different ways,
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I mean, we're going to talk about how intermittent fasting,
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AKA time-restricted feeding, impacts weight loss,
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fat loss in particular,
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muscle maintenance and loss and gain,
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organ health, such as gut health and liver health,
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the genome, the epigenome, inflammation, sickness,
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recovery and healing from sickness,
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exercise, cognition, mood, and lifespan.
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So we're going to cover a tremendous amount of information.
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I promise to make it all directly accessible,
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regardless of whether or not you have a background
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in biology and metabolic science or not.
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I'm also going to talk about a lot of tools.
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In fact, I'm going to discuss a number of tools
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during today's episode that actually make it such
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that you don't have to follow any feeding schedule
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or fasting schedule, same thing if you think about it,
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in any absolutely strict regimented way,
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meaning if you were to only eat
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during an eight-hour period of each day, most of the time,
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but then occasionally eat
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across a 12-hour period of the day.
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In theory, that could actually have
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pretty serious detrimental health effects.
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And yet there are things that you can do
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to attenuate those negative effects.
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In fact, there are things that you can do and or take
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that can make it as if you did not eat at all.
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And so we'll discuss what those tools are.
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And in many cases for sake of health, weight loss,
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making the body think that it did not eat at all
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can actually be quite beneficial.
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So today we're going to cover mechanism
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and we're going to cover tools.
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Before we do that,
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I want to highlight a particular result
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that was published recently
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because it serves as a useful backbone
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as we wade into the conversation about fasting.
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This is a study that was published
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in the journal Cell Metabolism,
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a cell press journal, excellent journal.
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And the title of the paper is Fasting Blood Glucose
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as a Predictor of Mortality, Lost in Translation.
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And I'll explain what the lost in translation part
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means in a moment.
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But the basic takeaway of this study,
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and I should mention that the first author of the study
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is Paliyaguru, P-A-L-L-I-Y-A-G-U-R-U, guru,
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The basic finding of the study is that in humans,
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higher blood glucose is associated with mortality.
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And in fact, if you look at blood glucose,
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resting blood glucose across the lifespan,
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what you find is as people age,
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resting blood glucose goes up.
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Now this is very interesting because for a long time,
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it was thought that metabolism actually goes down as we age.
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And to some extent that's true,
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but the reductions in metabolism are not nearly as robust
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as we once thought that they were across the lifespan.
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However, unless there's something done to mitigate
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the increase in blood glucose associated with aging,
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almost everybody experiences a gradual,
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but regular increase in resting blood glucose
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that predicts mortality.
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Now the title, as I mentioned,
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is Fasting Blood Glucose as a Predictor of Mortality,
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Lost in Translation.
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And the reason that they included lost in translation
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in the title is that what I just told you,
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that increases in resting blood glucose predict mortality
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or are correlated with mortality is true for human beings
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and for non-human primates, monkeys,
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but the opposite is true in mice.
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And so I thought it was important to use this study
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as an example of where studies in mice often,
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but not always translate to humans and to non-human primates.
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So today I'm going to be careful to distinguish
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when a study was performed in mice versus in humans,
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because it seems that at least when discussing feeding,
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blood glucose and other aspects of diet,
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as they relate to health and wellbeing,
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whether or not a study was performed in rodents
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or in humans can be very important.
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the results were directly 180 degrees opposite
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In other words, in mice, resting blood glucose went down
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and it was associated with mortality.
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So lower blood glucose associated with mortality,
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whereas in humans,
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higher resting blood glucose was associated with mortality.
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And obviously what we're mostly interested in
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is health and wellbeing of ourselves, of humans.
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I'm sure there are some people out there
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that are intensely concerned about the health
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and wellbeing of mice,
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which you could imagine a few rare contexts
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where that's important,
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but obviously most of us are interested in human health.
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So I'll be sure to emphasize when studies were performed
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in humans versus in mice.
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I'd like to emphasize that this podcast is separate
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from my teaching and research roles at Stanford.
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part of my desire and effort to bring zero cost
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to consumer information about science
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and science related tools to the general public.
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In keeping with that theme,
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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Roca.
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using the modern principles of neuroplasticity.
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Ben Edy, who's a teacher out in Pasadena,
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who has applied these tools,
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at least to my knowledge for the first time ever.
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Of course, all the tools that are there are listed out
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in what I call a plasticity super protocol.
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And all those tools can be applied to learning and teaching
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in any format that you like.
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It's in the caption to this week's episode
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and it will remain there.
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It's up on YouTube and I hope you enjoy it.
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Okay, so let's talk about feeding,
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fasting, health, and performance.
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And I want to just establish a few foundational terms
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so that we're all on the same page.
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rather than talk about fasting or time restricted feeding,
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I'm largely going to talk about time restricted feeding,
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but please understand that time restricted feeding
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is just one side of the coin that is a two-sided coin
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that includes fasting on the one hand, not eating,
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and time restricted feeding on the other hand.
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I may occasionally say fasting,
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but because fasting and eating establish
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different biological conditions in the body,
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time restricted feeding is the term that I will use
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to describe the overall plan
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of restricting one's eating window as it's called
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to a particular phase of each 24 hour day,
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or in some cases to particular days within the week,
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because as you'll soon learn,
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there are aspects of time restricted feeding,
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AKA fasting, that involve eating every other day
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or eating one way for five days
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and then fasting for two days and so forth.
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So I'll be very precise about what I mean
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and why I mean it, but for the time being,
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I'm going to refer to time restricted feeding
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as a way to put an umbrella over this conversation.
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I am going to emphasize a lot of biological mechanism.
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If you've listened to this podcast before,
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you know that I always begin with biological mechanism.
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I do describe tools of how to implement those mechanisms,
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but I wholeheartedly believe that knowing mechanisms
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and understanding how these processes work
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gives you tremendous flexibility and understanding
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and control over the processes
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of your mental and physical health.
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Whereas if I were to just list off a menu of things to do
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and not to do, those will work,
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but those will not give you the kind of understanding
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that would allow you to navigate through life,
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through travel, through dinners out,
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through different exercise schedules,
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whether or not you're one age or another age,
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male, female, et cetera,
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I'm giving you mechanisms so that you can gain more control
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over the systems in your brain and body.
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Everything's timestamped,
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so if you want to jump to the to-dos,
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you can certainly do that,
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but I encourage you to hang in there for the mechanism bit.
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I will make it all very clear
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because if you understand mechanism,
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you are in a true place of power
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and control over your biology.
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If ever there was a topic that is controversial,
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especially on the internet,
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it is that of diet and nutrition.
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So I'm wading into this with a smile
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and in eager anticipation of all the,
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but, but, but this, and but, but that, and wait,
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but this showed that.
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We need to precisely define what it is
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that we're talking about when we talk about nutrition.
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I'm going to give you an example of a study
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that was published a few years ago, 2018,
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by a colleague of mine at Stanford, Chris Gardner.
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So a terrific professor of nutrition
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and has done a lot of important studies
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on how nutrition impacts different aspects of health.
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This is a large scale study.
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It was published in JAMA,
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the Journal of the American Medical Association,
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one of the very top tier journals in the area of medicine.
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And certainly for a paper on nutrition to show up there
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meant that it had to meet an exceedingly high standard.
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This paper where Chris is the first author,
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it's Gardner et al, 2018 JAMA,
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looked at weight loss in people following
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one particular diet versus another particular diet.
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And this was a 12 month weight loss study.
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So it was focused specifically on weight loss,
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although they looked at some other parameters as well.
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And the basic conclusion of the study was that
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there was no significant difference in weight change
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between people following a healthy low fat diet
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versus a healthy low carbohydrate diet
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with significantly more dietary fats in them.
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This caused a lot of ripples in the world of nutrition
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and nutritional science,
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and certainly in the general population,
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because anyone that understands diet and nutrition
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would immediately say, but wait,
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there are all sorts of different implications
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of eating one type of diet,
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say low carbohydrate, higher fats,
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versus a higher carbohydrate, lower fat diet.
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And indeed there are.
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This study was focused specifically on fat loss
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and on weight loss.
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So as we discuss time restricted feeding,
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we need to be very precise about what are the effects
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of time restricted feeding and of eating in particular ways
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at particular times,
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we are going to emphasize again,
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whether or not the study was done in mice or in humans,
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in athletes and men and women or both.
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But the study from Gardner and colleagues
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is a beautiful study and really emphasizes that
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if one's main goal is simply to lose weight,
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then it really does not matter what one eats,
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provided that the number of calories burned
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is higher than the number of calories ingested.
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However, anyone out there who understands
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a little bit of biology or a lot of biology will agree
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that there are many factors that impact
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that calories burned part of the equation.
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Some of those are obvious.
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So for instance, amount of exercise,
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type of exercise, basal metabolic rate,
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how much energy one burns just sitting there.
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I've talked before on this podcast about meat,
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non-exercise induced thermogenesis,
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where if people bounce around a lot and fidget a lot,
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they can burn anywhere from 800 to 2000 calories per day.
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So their quote unquote basal metabolic rate
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is actually much higher simply because they're fidgeters.
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Whereas people who tend to be more stationary
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have a lower basal metabolic rate on average.
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There's a great science to support this.
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Metabolic factors and hormones are also very important.
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Hormones such as thyroid hormone and insulin
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and growth hormone and the sex story to hormones,
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testosterone and estrogen,
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those levels will also profoundly influence
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the calories out the calories of burned component
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of the calories in calories out equation.
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So if out there on the internet
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or in listening to a particular podcast or speaker,
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somebody says, this is the ideal diet
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or calories in calories out does not matter
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or calories in calories out is the only thing that matters.
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I think it's very important to understand
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that there are some foundational truths
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such as calories in calories out,
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but that of course hormone factors
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and the context in which a given diet regimen
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is taking place are exceedingly important.
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A good example of this would be puberty.
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At that time in life,
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sex story to hormones are changing profoundly in the body
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as our growth hormone and other hormones.
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And much of caloric intake
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is directed towards protein synthesis,
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towards the production of muscle and bone
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and other tissues of the body.
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And that's because of changes in hormones
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that we call puberty.
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So there's no way that we can drill into every aspect
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of a given feeding plan or feeding schedule
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that would allow us to tap into every aspect
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of the list that I read out before weight loss,
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fat loss, muscle, organ, genome, epigenome,
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inflammation, exercise, cognition, mood, and lifespan.
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But today we're going to be very precise
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about how time restricted feeding.
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It's very clear from both animal studies
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and human studies can have a very powerful
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and positive impact on everything from weight loss
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and fat loss to various health parameters.
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This is a beautiful literature that's emerged mostly
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in the last 10 or 15 years.
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And as we march into this literature,
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what you'll see is that there actually is a perfect diet
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for you on a given day.
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And that perfect diet for you on a given day is contextual,
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meaning it depends on what you did yesterday
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and what you're going to do tomorrow.
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So there is a perfect diet for you.
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And today I'm going to arm you with the mechanisms
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and understanding that will allow you to define
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what that perfect diet is,
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and will allow you to eat on a schedule
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and to eat the things that are going
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to best serve your goals.
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So let's talk about eating and what happens when you eat.
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And let's talk about fasting or not eating
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and what happens when you fast.
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I did an entire episode on eating and metabolism
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and hormones and other factors that impact appetite.
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We don't have time to go into all those details now,
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although you're welcome to listen to that episode as well.
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But we can briefly describe the overall conditions
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that are set in the body when we eat and when we don't eat.
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The key word here is conditions.
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If I can emphasize anything today,
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it's that what you eat and when you eat it,
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set conditions in your body.
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And those conditions can be very good for you
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or very bad for you, depending on when you eat.
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In fact, when you eat is as important as what you eat.
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When you eat is as important as what you eat,
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at least as it relates to health parameters,
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in particular, liver health and mental health.
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Some simple rules about eating.
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First of all, when you eat, typically your blood glucose,
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your blood sugar will go up.
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Also insulin levels will go up.
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Insulin is a hormone that's involved in mobilizing glucose
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from the bloodstream.
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How much your glucose and insulin go up
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depends on what you eat and how much you eat.
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In general, simple sugars, including fructose from fruit,
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but also sucrose and glucose and simple sugars
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will raise your insulin and blood glucose
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more than complex carbohydrates,
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things like grains and breads and pastas and so forth.
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And grains and breads and pastas and so forth
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will raise your blood glucose more
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than fibrous carbohydrates like lettuce and broccoli
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and things of that sort.
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Protein has a somewhat moderate or modest impact
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on insulin and glucose.
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And fat has the lowest impact
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on raising your blood glucose and blood insulin.
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So what you eat will impact how steep arise in blood glucose
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and insulin takes place.
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And there are a number of factors
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that are related to your individual health
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that will also dictate how steep and how high
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that rise in glucose and insulin will be.
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For the time being,
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I'm leaving out people who have type one diabetes.
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These are people that don't manufacture their own insulin
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and type two diabetes is essentially insulin insensitivity,
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lack of sensitivity to insulin,
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which leads to high blood glucose.
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But when you eat, blood glucose goes up
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and when you don't eat blood glucose and insulin go down.
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The longer it's been since your last meal,
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the lower typically your blood glucose and insulin will be.
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And the higher things like GLP-1,
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glucagon like peptide one,
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glucagon being a hormone that's also secreted
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when you are in a fasted state or a low blood glucose state.
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It's involved in mobilizing various energy sources
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from the body, including fat through what we call lipolysis,
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also using carbohydrates and potentially even using muscle
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as a source of energy.
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So that's kind of a fire hose of information
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about what happens when you eat and don't eat,
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but just think of it this way,
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blood sugar and insulin go up when you eat,
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they go down when you don't eat
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and other hormones go up when you don't eat.
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So there are hormones associated with the fasted state
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and there are hormones associated with the eating
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and having just eaten state.
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Now, the most important thing to understand
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is that like everything in biology,
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this is a process that takes time.
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So insulin and glucose go up when we eat
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and it takes some period of time for them to go down.
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Even if we stop eating,
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they will remain up for some period of time
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and then go back down.
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This is very important because if you look
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at the scientific literature on fasting,
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on time restricted feeding,
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it's absolutely clear that the health benefits,
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not just the weight loss benefits,
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but that the health benefits from time restricted feeding
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occur because certain conditions are met
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in the brain and body for a certain amount of time.
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And that gives us an anchor from which to view
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what eating is in terms of how it sets conditions
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in the body over time.
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And if that sounds overly analytic,
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I promise you this is the simplest and best way
link |
to think about any eating schedule or any eating plan.
link |
So I think it's fair to say that in the field of nutrition,
link |
there are a few landmark studies that serve
link |
as really strong anchors for building our understanding
link |
of what to eat and what not to eat and when to eat,
link |
depending on our goals.
link |
The Garner study that I mentioned earlier
link |
is one such study in that it says,
link |
if your goal is weight loss,
link |
it really does not matter what foods you consume
link |
provided that you consume a sub maintenance caloric diet.
link |
However, I want to emphasize again,
link |
that sets aside issues of adherence,
link |
meaning how easy or hard it is to adhere to a given diet.
link |
Some people find it much easier to follow a high fat,
link |
low carbohydrate diet.
link |
Some people follow a different diet
link |
because it's much easier for them to follow.
link |
And some people are concerned with mental performance
link |
and athletic performance.
link |
So that study doesn't say there's a best diet.
link |
What it says is that what you consume is less important
link |
than the amount of food that you consume,
link |
at least for sake of weight loss,
link |
not necessarily for sake of health.
link |
Now, the study that I'm going to refer to next
link |
is what I would consider the second major pillar
link |
of nutritional studies.
link |
This is a truly landmark study that was carried out
link |
by Sachin Panda, who is a professor
link |
at the Salk Institute of Biological Studies in San Diego,
link |
an absolutely phenomenal institution
link |
and an absolutely phenomenal researcher.
link |
I've known Sachin for a number of years.
link |
And I want to emphasize that the current literature
link |
on intermittent fasting and time restricted feeding
link |
can largely be attributed to Sachin
link |
and the work that he's done.
link |
There are others involved too, of course.
link |
And of course, time restricted feeding and fasting
link |
has a rich history that goes back many hundreds,
link |
if not thousands of years in different cultures
link |
and religions, but the science of time restricted feeding
link |
can really mainly be attributed to the incredible work
link |
that Sachin has done.
link |
And I'm grateful to consider him a friend and a colleague.
link |
And we consulted at length in anticipation of this episode.
link |
I also hope to have him on as a guest in the future.
link |
The landmark paper that came from Sachin's lab
link |
was published in 2012.
link |
This was a paper in mice that set the basis
link |
for studies in humans that came later.
link |
And the title of this paper is time restricted feeding
link |
without reducing caloric intake prevents metabolic diseases
link |
in mice fed a high fat diet.
link |
So the title tells us a lot.
link |
It says that what's varied in this study
link |
is not what these mice ate.
link |
It was when they ate it.
link |
And there were essentially four conditions in this study
link |
and the results are absolutely remarkable.
link |
So I'm going to walk you through the major results.
link |
What they did is they gave mice access
link |
to different types of food.
link |
There were four groups.
link |
One group of mice had access to just a normal mouse diet.
link |
It would not be a diet that you'd be very interested in.
link |
I confess I've actually tasted mouse chow.
link |
If you work with mice at all,
link |
you just have to do it at least once.
link |
It doesn't taste very good.
link |
It tastes like a very bland graham cracker cookie.
link |
And I confess that I only had the tiniest little bit,
link |
but mice like that stuff.
link |
And if you allow them to eat that stuff,
link |
what's called ad libitum, whenever they want,
link |
you just keep it in their food 24 hours a day,
link |
they will eat sometimes,
link |
and then they won't eat it at other times.
link |
Or in this case, they also had a condition
link |
where they gave them mouse chow in a time restricted way,
link |
just for a certain number of hours each day,
link |
about eight hours.
link |
Or they gave them a high fat diet that was a separate group,
link |
got a high fat diet at any time they wanted.
link |
So this was kind of the carnival for mice
link |
because mice really like high fat, highly palatable foods.
link |
And so they got a lot of goodies and high fat in their food.
link |
And then there was a fourth group that had access
link |
to the high fat diet as much as they wanted to eat,
link |
but only during a restricted time period
link |
of each 24 hour cycle.
link |
Now mice are nocturnal, humans are what we call diurnal.
link |
Actually, we're not really diurnal, we're crepuscular,
link |
which means that we're most active in the morning
link |
and in the evening, not so much in the afternoon.
link |
But nonetheless, everything I'm going to tell you
link |
is true also for humans.
link |
And we know this now from human studies.
link |
One of the most important things to take away
link |
from the study was that mice that ate a highly palatable,
link |
high fat diet, a great tasting diet,
link |
but only during a restricted feeding window
link |
of each 24 hour cycle,
link |
maintained or lost weight over time.
link |
Whereas mice that ingested the same diet,
link |
same amount of calories,
link |
but had access to those calories around the clock,
link |
gained weight, became obese and quite sick.
link |
And as an additional second point,
link |
the mice that restricted their feeding window
link |
to a particular portion of eight hours
link |
of every 24 hour cycle actually showed some improvement
link |
in important health markers.
link |
And what was even more incredible is that mice
link |
that only ate during a particular feeding window
link |
also experienced some reversal
link |
of some prior negative health effects.
link |
So this study really lit up the world
link |
and got people excited about time restricted eating.
link |
Again, they used an eight hour feeding window.
link |
The story around that eight hour feeding window
link |
is kind of interesting though.
link |
Not many people know this
link |
because it wasn't included in the paper
link |
and there was no reason to include it in the paper,
link |
not to out anybody,
link |
but it turns out that the reason
link |
they used an eight hour feeding window
link |
and not a nine hour or a 10 hour feeding window
link |
is because studies of this sort are actually quite demanding
link |
to perform and require the constant presence
link |
of the graduate student or postdoc there
link |
to ensure that the food is in the cages at particular times
link |
and not in the cages at other times.
link |
And mice are really good at hiding food.
link |
They'll even hide food in their jowls.
link |
And so there's a lot of work that has to be done
link |
to prepare for that eight hour feeding window
link |
and to make sure after that eight hour feeding window,
link |
there's all the food has been removed from the cage
link |
and from the jowls of the mice and so forth.
link |
And it turns out that the significant other
link |
of the graduate student and or postdoc,
link |
I won't reveal who they were running this study,
link |
forbid their significant other, the scientist,
link |
from being in the lab for periods of time
link |
that were much longer than the 10 or 12 hours
link |
that were required in order to ensure
link |
this eight hour feeding window.
link |
So when we hear the eight hour feeding windows are holy,
link |
they are not holy.
link |
And later we are going to talk about how eating for a time
link |
that's restricted to eight hours versus 10 hours
link |
versus 12 hours, for instance,
link |
how that impacts various parameters like health parameters
link |
and weight loss, et cetera.
link |
But the eight hour feeding window was actually created
link |
because of a real world constraint on the research
link |
and the relationship with the researcher
link |
performing the research,
link |
not because there's anything holy
link |
about an eight hour feeding window.
link |
Now, an important point about when the feeding window falls
link |
within the 24 hour cycle,
link |
it is very important that the feeding window fall
link |
during the more active phase of one's day.
link |
So for humans, that's typically in the early part of the day
link |
or the later part of the day, but not at night.
link |
Put very simply, there are a lot of data now
link |
pointing to the fact that eating during the nocturnal phase
link |
of the 24 hour cycle is very detrimental to one's health.
link |
In fact, when we eat can either enhance our health
link |
or can diminish our health.
link |
When we see light can enhance our feelings of wellbeing
link |
or can diminish our feelings of wellbeing.
link |
I've talked many times before about this
link |
on the Huberman Lab podcast that during the daytime,
link |
you want to get as much sunlight
link |
and other types of bright light in your eyes
link |
as is safely possible.
link |
And then you want to avoid light
link |
in the middle of the night.
link |
It has detrimental dopamine lowering effects,
link |
can cause depression, cortisol increases, et cetera.
link |
So when you view light is as important
link |
as the light that you view and when you eat
link |
is as important as what you eat.
link |
In this study, they saw something really interesting,
link |
which was that not only did restricting food
link |
to a particular phase of the 24 hour cycle
link |
benefit things like lean body mass and fat loss
link |
and a number of health parameters
link |
that I'll talk about in a moment,
link |
but it also anchored all the gene systems of the body
link |
and provided a more regular stable
link |
so-called circadian rhythm or 24 hour rhythm.
link |
You may be surprised to learn that 80%,
link |
80% of the genes in your body and brain
link |
are on a 24 hour schedule.
link |
That is they change their levels going from high to low
link |
and back to high again across the 24 hour cycle.
link |
And when those genes are high at the appropriate times
link |
and low at the appropriate times,
link |
meaning their expression is high and low
link |
at the appropriate times,
link |
and therefore the proper RNAs and proteins are made
link |
because DNA encodes for RNA,
link |
RNA is translated into proteins.
link |
When that happens, your health benefits.
link |
When those genes are not expressed at the right times,
link |
when they're high or low at the wrong times
link |
of each 24 hour cycle,
link |
that's when you get negative health effects.
link |
This study showed that when mice restrict their eating
link |
to an eight hour period within the most active phase
link |
of their 24 hour cycle,
link |
many of the genes that are associated
link |
with these so-called circadian and clocks,
link |
these genes have names like per, bmal, cry1, et cetera.
link |
Those so-called clock genes underwent
link |
a very regular entrainment,
link |
a locking in to the proper 24 hour schedule.
link |
And while this was in mice,
link |
we now know that this also occurs in humans.
link |
I've said before on this podcast, and I'll say it again,
link |
that light and when we view light is the primary way
link |
in which these genes and the clock systems of our body
link |
get organized or entrained,
link |
meaning matched to the outside light dark cycle.
link |
So viewing light early in the day and in the afternoon
link |
and as much as possible all day, great.
link |
Ideally that sunlight avoiding light in the middle
link |
of the night is also great.
link |
It's great because it causes the increases
link |
in particular genes and the decreases in particular genes
link |
in every cell throughout your body
link |
at the appropriate times.
link |
The second most powerful timekeeper or zeitgeber
link |
as it's called is food and when you eat.
link |
And in this study, the results they saw underscore
link |
this point, what they saw is that the peaks
link |
in these clock genes became very regular
link |
and the dips in these clock genes became very regular.
link |
And that led to a whole host
link |
of really important positive health effects.
link |
Conversely, when mice ate whenever they wanted
link |
across the 24 hour cycle,
link |
these clock genes became really out of whack
link |
and the negative health consequences
link |
were the downstream result of these changes
link |
in these clock genes.
link |
This has now also been shown to be true for humans.
link |
So if you want to be healthy, you want your organ health,
link |
your metabolic health to be entrained properly.
link |
One of the most important things you can do is to view light
link |
at the appropriate times of each 24 hour schedule
link |
and to not view light at other times of that schedule.
link |
And to eat at the appropriate time of each 24 hour day.
link |
Now, again, there are rare instances
link |
that we will discuss when skipping entire days
link |
or entire 24 hour cycles of eating can be beneficial.
link |
But for now, we're talking about schedules
link |
of time restricted feeding that involve a window
link |
of feeding that falls during your more active phase.
link |
So during the daytime, putting aside people
link |
that work shift work during the daytime
link |
is when you want to eat.
link |
And this eight hour feeding window provided a very strong
link |
reinforcing signal that combines with light
link |
to ensure that these genes are expressed
link |
at the appropriate times.
link |
The short takeaway from this is you probably want
link |
to think about and perhaps even engage
link |
in time restricted feeding.
link |
So as I mentioned earlier,
link |
when mice can eat around the clock, bad things happen.
link |
And one of the bad things that happens
link |
is that the liver suffers.
link |
The liver is involved in all sorts of things,
link |
production of important hormones
link |
and other factors related to metabolism.
link |
And when mice can eat around the clock,
link |
their livers got very sick, fatty deposits in the liver,
link |
other factors in the liver,
link |
essentially taking down the pathway of liver disease.
link |
The time restricted feeding essentially reversed that
link |
or led in many cases to even healthier liver conditions.
link |
And that's based on this study,
link |
but also additional studies also now in humans.
link |
So restricting your feeding to a particular window
link |
every 24 hour cycle has clearly been shown now
link |
in mice and in humans to enhance liver health,
link |
which is wonderful.
link |
How does it do this?
link |
Well, it happens because food intake,
link |
as I mentioned earlier,
link |
sets certain conditions in the body
link |
that lasts for a period of time.
link |
Anytime we eat, whether or not we are a mouse or a human,
link |
there's a period of time that's required
link |
for so-called digestion,
link |
but also gastric emptying and other processes related
link |
to breaking down that food and utilizing it.
link |
And that is an active process.
link |
It requires energy.
link |
And that process of breaking down food
link |
involves certain cellular functions
link |
that if they're ongoing throughout the 24 hour cycle
link |
or even extended too far across the 24 hour cycle,
link |
meaning you're eating across a 14 or a 16 hour
link |
and 18 hour window that causes serious problems.
link |
And this has now been established because of the fact
link |
that it increases the expression of different proteins
link |
and genes in the body, such as TNF alpha, IL-6, IL-1.
link |
What are all those things?
link |
They are pro-inflammatory markers.
link |
So the reason that the liver gets sick
link |
when you're eating too often
link |
is because inflammatory markers are increased.
link |
These inflammatory markers are not inherently bad.
link |
They're there for a reason,
link |
but they are there in order to respond
link |
to certain challenges, immune challenges,
link |
or the ingestion of food and the breakdown of food.
link |
But then in an ideal circumstance,
link |
they are reduced in the period
link |
in which there's no food present in the digestive tract
link |
or in which there's very little food present
link |
in the digestive tract.
link |
So by eating around the clock,
link |
you're making yourself sicker.
link |
By eating at restricted periods of time each 24 hour day,
link |
you're actually making yourself healthier
link |
and you're activating certain processes
link |
that can positively impact both weight,
link |
either maintenance or loss of weight.
link |
We'll talk about weight gain a little later
link |
and positively impacting things like liver health.
link |
Also the expression of different things
link |
related to brown fat,
link |
the fat that increases your metabolism.
link |
We will return to this also a little bit later
link |
and blood glucose regulation.
link |
So the takeaway from this study,
link |
in fact, there are many takeaways from this study.
link |
It's so wonderful is that liver health,
link |
bile acid metabolism, energy expenditure,
link |
inflammation, liver metabolites,
link |
many, many aspects of our health
link |
are impacted by when we eat, not just what we eat.
link |
As we move forward and we talk about intermittent fasting
link |
for eight hour windows, six hour windows,
link |
12 hour windows for all sorts of different
link |
intents and purposes,
link |
I want to start to establish a foundational protocol
link |
that all of us, any of us can use
link |
in order to maximize your particular goals.
link |
There are some absolutes within this realm
link |
of time restricted feeding.
link |
Here are a couple of absolutes
link |
that you would want to consider.
link |
First of all, it pays off in the metabolic sense
link |
and in the health sense
link |
and in the weight maintenance or loss sense
link |
to not ingest any food in the first hour after waking
link |
and potentially for longer.
link |
So I want to repeat that.
link |
One of the key pillars of intermittent fasting
link |
is that for the first hour after you wake up
link |
and potentially for longer to not ingest any food, okay?
link |
The second major pillar that's well supported by research
link |
is that for the two and ideally three hours
link |
you also don't ingest any food
link |
or liquid calories for that matter.
link |
And we will talk about what it means to break a fast
link |
and whether or not certain liquids,
link |
even coffee and tea can break a fast, et cetera,
link |
But just as a foundation,
link |
it's very clear from the research in humans
link |
that not eating any food or ingesting any calories,
link |
liquid or otherwise,
link |
for the first 60 minutes after waking up each day
link |
and for the two to three hours prior to your bedtime,
link |
that's ideal for the parameters
link |
that we've discussed earlier,
link |
all the different things like weight and liver health
link |
and metabolic health and so forth.
link |
The two most common questions about intermittent fasting
link |
are when is the ideal time for the eating window?
link |
Is it early in the day, the middle of the day,
link |
or late or in the day?
link |
And how long should that eating window be?
link |
Should it be eight hours?
link |
We already heard why the eight hour window
link |
was first established.
link |
It was because of these lab conditions
link |
and the conditions of the particular relationship
link |
of the graduate student involved,
link |
or should it be seven hours or six hours or 12 hours?
link |
Turns out that there's some general frameworks
link |
that we can follow in order to answer these questions.
link |
As we move into this portion of the discussion,
link |
I want to highlight a very important reference
link |
that just came out, literally came out last week
link |
in the journal, endocrinology reviews.
link |
And the title of this review is time restricted eating
link |
for the prevention and management of metabolic diseases.
link |
Although the data in this paper
link |
go well beyond metabolic diseases.
link |
This is a paper from Sachin Panda's lab.
link |
It's a very lengthy review with an enormous table
link |
that's beautifully organized,
link |
that scripts out all the studies done in humans,
link |
well over a hundred studies,
link |
looking at time restricted feeding in athletes,
link |
men, women, children, diabetes, no diabetes, et cetera,
link |
with detailed references and description of the outcomes.
link |
Spent a lot of time with this review,
link |
even though it just came out recently,
link |
and is a absolute goldmine resource.
link |
It is also the major resource
link |
for everything I'm about to tell you
link |
if you would like to delve deeper into the material.
link |
So let's deal with this first question
link |
of when is the ideal feeding window?
link |
And here again, we're thinking about a schedule of eating
link |
that involves eating at least once every 24 hours,
link |
not two day or three day or every other day fast.
link |
So it turns out that the answer to the question,
link |
when is it best to eat, is actually best answered
link |
by thinking about the other side of the coin,
link |
which is when is it best to fast?
link |
So because we are fasting during sleep,
link |
it's very clear that it's best to extend
link |
the sleep-related fast either into the morning
link |
or to start it in the evening.
link |
Now, this might seem kind of obvious,
link |
but it's actually not so obvious.
link |
You could place that feeding window early in the day,
link |
middle of the day, or late in the day.
link |
Let's think about what happens when we sleep.
link |
When we sleep, our body undergoes a number
link |
of different processes in the brain and body
link |
in order to recover the cells and tissues.
link |
Many of you have probably heard of autophagy,
link |
which is essentially a cleaning up, a gobbling up
link |
of dead cells and cells that are injured or sick.
link |
And this is a natural process that occurs,
link |
and it occurs mainly during sleep,
link |
although not only during sleep.
link |
Fasting of any kind does tend to enhance autophagy.
link |
It is not the only way to create autophagic conditions.
link |
Autophagic conditions can be created simply
link |
by following a sub caloric diet.
link |
And there are other things that one can do
link |
in order to trigger autophagy,
link |
but fasting does trigger autophagy.
link |
So when we're asleep,
link |
the bad cells are getting gobbled up and eaten,
link |
and the good cells also are undergoing
link |
certain repair mechanisms mainly related to,
link |
or at least governed by those circadian genes
link |
that we talked about earlier, those clock genes.
link |
So you're already fasting when you're asleep.
link |
And how deep you are into that fast depends
link |
on how long it was since your last meal.
link |
So if you fast early in the day
link |
and you've been asleep for five, six, seven, eight hours,
link |
I would hope somewhere between six and eight hours
link |
for most people is going to be beneficial.
link |
When you wake up, I mentioned earlier
link |
that you don't want to eat
link |
for at least the first 60 minutes after waking,
link |
but were you to extend that fasting to say 9 AM, 10 AM,
link |
11 AM, or even 12 noon or later,
link |
you are taking advantage of the deep fast
link |
that you were in during sleep
link |
and certainly toward the end of sleep.
link |
Now, why do I say deep fast?
link |
Well, because when we eat,
link |
the clearance of that food from our gut
link |
and the processes in our cells and organs
link |
that are related to digestion
link |
and the utilization of that food
link |
takes about five to six hours.
link |
So if you eat a meal and that meal lasts 10 minutes,
link |
20 minutes, or 30 minutes, or even an hour,
link |
and then you stop eating, you've stopped eating,
link |
but you are not fasting at that point.
link |
You can say you're fasting
link |
because you're no longer putting food
link |
into your digestive tract,
link |
but you are not in a fasted state.
link |
You are not under conditions of fasting.
link |
Later, I'll talk about things that you can do
link |
to accelerate the transition into fasting.
link |
So one thing is certain that you want your eating window
link |
to be tacked or attached to your sleep-based fasting
link |
in a way that makes it easier for you
link |
to get into the fasted state for a period of time.
link |
So we can view that point
link |
from the perspective of best, better, and worst, okay?
link |
So if you are like most people and you sleep at night,
link |
you're waking up somewhere around 6.37 AM
link |
or maybe even 8 AM,
link |
let's say you were to push your fasting window out
link |
such that you started eating at noon
link |
and then you stopped eating at 6 PM.
link |
Well, then you're not eating from 6 PM
link |
until let's say your bedtime is 10 PM,
link |
but from 6 PM to 10 PM,
link |
your body is not yet in a fasted state
link |
because you just ate.
link |
However, you're starting to taper into a fasted state
link |
before sleep and then all through sleep
link |
and until the next morning and late morning,
link |
you are actually in a fasted state.
link |
Now, most people find it very hard
link |
to only eat in the middle of the day.
link |
So while that's best,
link |
it's ideal for sake of the fasting-related improvements
link |
in health, it is not ideal
link |
and it's not very applicable
link |
to most work and family and social situations.
link |
Most people eat breakfast with others
link |
and or eat dinner with others.
link |
Some people eat lunch with others,
link |
but in general, it's hard to restrict your feeding window
link |
to just the absolute middle of the day.
link |
But from a purely health perspective,
link |
in a very objective way, that would be the ideal situation.
link |
Let's imagine a different pattern of eating
link |
where the feeding window starts in the afternoon,
link |
starts around two or even 3 PM.
link |
Some people don't have much trouble
link |
or they can train themselves to get their feeding window
link |
out to two or 3 PM
link |
and then they will eat until 10 or 11 PM, right?
link |
If you do the math,
link |
you realize that that feeding window is still pretty short.
link |
It still constitutes what we would call intermittent fasting
link |
or time restricted feeding.
link |
But assuming that they go to bed around 11 PM or midnight,
link |
they are not actually fasted in sleep
link |
because for the first six hours or so of sleep,
link |
maybe five, but probably more like six hours of sleep,
link |
they're still digesting the food
link |
that they consumed late in the night.
link |
It does appear beneficial to grab ahold of
link |
that sleep related fast,
link |
meaning you don't want your feeding window
link |
to be too close to bedtime.
link |
And that's why we came up with this
link |
kind of foundational pillar
link |
that I discussed with Sachin earlier,
link |
which is at least no eating for the first hour after waking,
link |
but also no eating within two to three hours prior to bed.
link |
And because we all need to sleep
link |
and sleep is exceedingly important
link |
for our health of all kinds,
link |
you want to prioritize sleep,
link |
but because we also have to eat,
link |
then you start to think about this
link |
and maybe it's not so good
link |
to push that feeding window too late in the day,
link |
because when you go to sleep,
link |
you're not actually capitalizing
link |
on the sleep related fasting.
link |
Now it's not just the case
link |
that it's easiest to fast while in sleep,
link |
although that's true because when we're asleep,
link |
typically we're not hungry or looking for food
link |
or foraging for food or wanting food
link |
or trying to resist food, we're just sleeping.
link |
There is something special about the fasting
link |
that occurs during sleep because it's associated
link |
with a number of processes
link |
that relate to the so-called glymphatic system,
link |
the movement of lymph-like fluids
link |
and other fluids through the brain
link |
are kind of sweeping out a garbage disposal, if you will,
link |
a clearing out of the metabolic debris
link |
and some of the autophagy that's associated
link |
with bad processes in the brain.
link |
So we could do a whole episode on this,
link |
but essentially during sleep
link |
and in particular during fasted states of sleep,
link |
we are undergoing a number of automatic cellular processes
link |
that clear out debris from our brain,
link |
enhance cognition, or at least offset dementia,
link |
this is now well-established,
link |
as well as a number of the same processes
link |
occurring in the organs of our body.
link |
So what we're starting to see here
link |
is that there are a number of constraints
link |
on when you can eat.
link |
Now I would be remiss if I didn't acknowledge
link |
the social constraints and the real life constraints.
link |
Some of us, because we want to eat with our family
link |
and because our family or our significant others
link |
eat around eight or 9 p.m.
link |
and that's the only time we're together,
link |
you have to eat late in the day.
link |
And that's certainly not a sin.
link |
I'm not saying that's good or bad.
link |
Here we're trying to establish, if you recall,
link |
best, better, and worst.
link |
So from both a practical and a health perspective
link |
and a purely objective view
link |
of how intermittent fasting works and can benefit us,
link |
starting to eat each day somewhere around 10 a.m.
link |
or around noon, and then allowing a feeding window
link |
that goes until six or maybe 8 p.m.,
link |
that seems to me, at least based on the data
link |
and what I understand about typical cultures
link |
where people eat in the daytime and in the evening,
link |
that seems to me like the kind of schedule
link |
that will allow you to get the most
link |
out of intermittent fasting, time-restricted feeding,
link |
but does not set you up to be really out of sync
link |
with the social rhythms in most cultures.
link |
If you think about it from the perspective of say,
link |
a noon to eight feeding window,
link |
what you'll find is that you're able to eat lunch
link |
with others, if you like, or by yourself,
link |
you will be able to eat dinner at a reasonable hour,
link |
at least in most countries, in most cultures,
link |
eating dinner somewhere between 6.30 and 7 p.m.
link |
When you say a feeding window that goes until eight,
link |
that doesn't mean sitting down to dinner at eight.
link |
That means your last bite of food or ingestion
link |
of any liquid calories was at 8 p.m.
link |
Assuming that you go to bed somewhere between 10 p.m.
link |
and 1 a.m., that allows this tapering off
link |
or this transition from feeding to a fasted state
link |
and still allows you to capitalize on the special period
link |
of fasting that is sleep-related fasting.
link |
And again, I want to emphasize that the fasting
link |
that occurs during sleep is vital
link |
and eating too close to sleep will disrupt
link |
that fasting-related sleep.
link |
Now, there are a number of caveats
link |
and details related to this,
link |
and there's an important caveat and detail related
link |
to people that are specifically interested
link |
in increasing or maintaining muscle mass.
link |
So first let's talk about food volume and food type
link |
and how that relates to whether or not you quickly
link |
or slowly enter a fasted state,
link |
because clearly when we talk about a feeding window,
link |
that feeding window could include any number
link |
of different foods.
link |
It could involve cake and ice cream, pizza, hamburgers,
link |
plants, fruit, whatever it is,
link |
or it could involve just fats or just proteins, et cetera.
link |
There are at least three factors that are going
link |
to govern how quickly you transition
link |
from ingesting food to a fasted state.
link |
Remember, as you ingest your last bite or sip of calories,
link |
that's not when the fast begins.
link |
That might be when the fasting begins on your watch
link |
or on one of these apps that I'll refer to later,
link |
which can help you track your fasting and eating windows,
link |
but that's not when it actually begins
link |
because your body is still seeing food.
link |
You're actually carrying around food inside of you.
link |
Even though you're not putting it into your mouth,
link |
you're still eating in some sense.
link |
So it should be somewhat obvious that very large meals
link |
are going to take longer to digest than very small meals.
link |
So that will impact how slowly or quickly you migrate
link |
from a fed state to a fasted state.
link |
There's no way I can spell out what exact volume of food
link |
you should ingest based on the size of your stomach
link |
But you're all familiar with being extremely full,
link |
very full, comfortably full, somewhat full,
link |
or not feeling full and feeling hungry.
link |
So learning to gauge food volume is important.
link |
Also foods that include some fats or a lot of fats
link |
will tend to slow gastric emptying time.
link |
And depending on the kind of fats,
link |
it could mean that a given meal is digested
link |
within three hours versus five hours.
link |
So more fats might be a large meal with a lot of fats
link |
has been going to take five or six hours.
link |
A smaller meal with less fat is going to be digested
link |
Consuming calories in liquid form is going to mean
link |
that gastric emptying time is going to be faster.
link |
And then of course,
link |
there's the glucose and the insulin aspect to it,
link |
which is that foods that lead to big steep rises in glucose,
link |
like pure sugars, then your glucose will drop.
link |
However, if they're combined with fats,
link |
then it tends to be a more gradual rise in glucose
link |
and it's more sustained, et cetera.
link |
Fibrous foods will also create a more long lasting
link |
sustained release in glucose.
link |
The important thing here is to establish a feeding window
link |
that you can comfortably manage, okay?
link |
Meaning that on average,
link |
you can obey a six hour feeding window
link |
or an eight hour feeding window or a 10 hour feeding window.
link |
And then to place that feeding window in a social
link |
and life context that you can manage on a regular basis.
link |
Now there are two key points that have been gleaned
link |
from the scientific data about this feeding window
link |
and when to place it.
link |
And this is based on a really important experiment
link |
that Satchin and his colleagues have been doing.
link |
There's a website that they have,
link |
a zero cost website called My Circadian Clock.
link |
You can go to this website free of cost.
link |
There are a number of important resources there,
link |
but what they've done is they've examined
link |
the feeding behavior of thousands of people.
link |
People will take a picture of the food they're about to eat
link |
and it enters into their account,
link |
maybe your account if you create one on My Circadian Clock.
link |
And they do this over many days or weeks.
link |
What's great about this is it establishes
link |
what's essentially called a phytogram,
link |
a time in which people ate.
link |
And a number of important findings have emerged
link |
from these phytograms across large populations
link |
of people in different time zones
link |
with different schedules, et cetera.
link |
First of all, almost everybody underestimates
link |
their feeding window.
link |
Meaning people who think that they are
link |
on an eight hour feeding window or six hour feeding window,
link |
when their data are analyzed,
link |
it almost is always the case
link |
that they're actually on a feeding window
link |
that's one or even two hours longer than they think.
link |
You think, well, how could that possibly be?
link |
If people are taking their first bite at noon
link |
and they're taking their last bite at 8 p.m.,
link |
well, that must mean that they are on that feeding window
link |
And it turns out that people cheat,
link |
but they don't cheat in any kind of obvious way.
link |
They might have, you know, a glass of wine after dinner,
link |
or they'll have a cup of tea and a little bite of a cookie.
link |
And so when people are honest and they are honest
link |
in most cases for this experiment,
link |
what you find is that most people's eating window
link |
is actually quite a bit longer.
link |
So in discussing this with Sachin
link |
and reviewing the literature,
link |
it's clear that if you'd like to be
link |
on a 10 hour feeding window,
link |
that you should probably select an eight hour feeding window
link |
because there's always a little bit of a taper
link |
on either side of that eating window.
link |
Very few people are extremely strict
link |
about these eating windows.
link |
It's just hard to do in the context of life events
link |
and social gatherings and family and so forth.
link |
Okay, so as we build forward your ideal fasting
link |
slash time restricted feeding schedule,
link |
we now have several different rules that we can list out.
link |
First, at least no food for the first hour after waking up,
link |
at least one hour.
link |
Two, no food intake for two
link |
and ideally three hours prior to your bedtime.
link |
Three, if you want to select an eight hour feeding window,
link |
then you should probably focus
link |
on a six or seven hour feeding window
link |
because in reality your feeding window
link |
is going to be longer.
link |
Reality meaning real life constraints.
link |
And if you'd like to be on a 10 hour feeding window,
link |
you should probably select an eight
link |
or a nine hour feeding window
link |
because the way it plays out is that people
link |
almost always eat outside of their eating window somewhat.
link |
The other nice thing about selecting
link |
a slightly shorter eating window
link |
than is comfortable for you
link |
is that it takes into account
link |
that as you take your last bite
link |
or your last sip of calories,
link |
there's this time or taper
link |
before which you are actually in a fasted state.
link |
And because you're eating different things
link |
on different days presumably,
link |
some foods leave your gut more quickly,
link |
some things spike your insulin
link |
and your glucose more than others.
link |
Sometimes you eat more fat, sometimes less fat.
link |
This allows you to fall well within the margins
link |
of the benefits of time restricted feeding
link |
that have been demonstrated in humans,
link |
which generally involve an eight hour window or so.
link |
So I think this eight hour window
link |
or six hour window is a good thing
link |
to shoot for for most people.
link |
Some people, and we will discuss the exceptions,
link |
but some people truly are exceptions to this.
link |
They just require more food.
link |
And along those lines,
link |
I just now briefly want to touch on some of the studies
link |
that have looked at using a very short feeding window
link |
of about four hours.
link |
Nowadays, a number of people are doing
link |
the so-called one meal per day
link |
or are restricting their feeding window
link |
to just four hours or six hours.
link |
And that turns out to be an interesting strategy.
link |
And the data around it actually are a little bit surprising.
link |
One surprising thing to leap out
link |
of this massive literature review
link |
on time restricted feeding in humans
link |
is that relatively short feeding windows
link |
of say four to six hours
link |
do produce a number of positive health effects,
link |
things like increased insulin sensitivity,
link |
which we know is good.
link |
Remember type two diabetes is a reduction
link |
in insulin sensitivity,
link |
improvements in beta cell function and the pancreas,
link |
decreased blood pressure,
link |
decreased oxidative stress,
link |
decreases in things like evening appetite.
link |
So positive health effects
link |
and psychological effects in general.
link |
However, they either produce no change in body weight
link |
or they tend to produce even increases in body weight.
link |
Now, of course, there's variation between individuals
link |
and between studies,
link |
but this is somewhat surprising.
link |
So the eight hour feeding window
link |
seems to be very beneficial
link |
across almost all the parameters that we've discussed,
link |
inflammation, weight loss, fat loss, et cetera.
link |
And adherence, I should mention,
link |
people's ability to stick to the diet
link |
seems quite good on this eight hour feeding windows.
link |
But when people try and undergo
link |
very short feeding windows of four to six hours,
link |
it seems that they are overeating
link |
in that four to six hours,
link |
at least overeating with respect to their metabolic needs.
link |
Now, the contrast to this
link |
is the so-called one meal per day schedule.
link |
Very few studies on one meal per day.
link |
One meal per day, unless it's a very, very long meal,
link |
typically would not last four to six hours,
link |
because it sort of depends on how you define a meal.
link |
But when you look at the very few,
link |
I should emphasize again,
link |
very few studies on one meal per day,
link |
people typically maintain or lose weight
link |
on the one meal per day schedule.
link |
So what we can say
link |
is that the seven to nine hour feeding window
link |
produces all of the major health benefits
link |
of time-restricted feeding,
link |
as well as being pretty straightforward
link |
for most people to adhere to on a regular basis.
link |
And on a regular basis turns out to be very important.
link |
I'll get back to that point in a moment.
link |
Whereas the four to six hour eating window
link |
doesn't seem to serve people
link |
as well as say a seven or eight hour eating window,
link |
simply because people are overeating
link |
during that eating window.
link |
And the one meal per day,
link |
while perhaps ideal for certain people's schedules,
link |
may actually cause people to under eat.
link |
And in some cases that might be what people want.
link |
They actually want to under eat.
link |
But when we start thinking about performance
link |
in work and in sport,
link |
and when we start considering hormone health
link |
and hormone production, fertility,
link |
that's when we can really start to look at
link |
the seven to nine hour feeding window
link |
versus the four to six hour feeding window
link |
versus the one meal per day type feeding window
link |
with some different objectivity.
link |
We can start to look at it through a different lens,
link |
because it turns out that when you place the feeding window
link |
and how long that feeding window is
link |
actually will impact a number of other things
link |
in particular hormones that can be very important
link |
for a number of things related to sex and reproduction
link |
can be related to performance at work,
link |
performance in athleticism.
link |
And there are excellent studies on this.
link |
So let's explore those now.
link |
So let's talk about some conditions
link |
where having the feeding window early in the day
link |
would actually be very beneficial.
link |
There was a study that was published recently
link |
in Cell Reports, again, Cell Press Journal,
link |
excellent journal, peer reviewed, very stringent
link |
from Aoyama et al.
link |
So this is A-O-Y-A-M-A et al.
link |
This was published just recently in July, 2021
link |
that looked at the distribution of protein intake
link |
in different meals delivered either early in the day
link |
or later in the day.
link |
And I'm summarizing here quite a lot,
link |
but I should mention that this study was performed
link |
in both mice and humans, same paper, mice and humans,
link |
and involved hypertrophy training,
link |
essentially increasing the weight bearing of given limbs
link |
to try and induce hypertrophy,
link |
which is the growth of muscle tissue.
link |
It does appear that muscle tissue is better able
link |
to undergo hypertrophy by virtue of the fact
link |
that there's better or enhanced protein synthesis
link |
early in the day because of the expression
link |
of one of these particular clock genes called BMAL, B-M-A-L.
link |
BMAL regulates a number of different protein synthesis
link |
pathways within muscle cells,
link |
such that eating protein early in the day
link |
supports muscle tissue maintenance and or growth.
link |
And in this study, they also looked at the effects
link |
of supplementing so-called BCAAs, branch chain amino acids,
link |
which is popular in bodybuilding circles
link |
and in strength training circles.
link |
And BCAAs are essential components
link |
of a number of different foods,
link |
but can also be supplemented.
link |
The takeaway of this study is pretty straightforward.
link |
However, the takeaway is if your main interest
link |
is maintaining and or building muscle,
link |
then it can be beneficial to ingest protein early in the day.
link |
You would still want to obey this,
link |
what we're calling a kind of foundational rule
link |
of not eating any food for the first hour post-waking,
link |
or at least the first hour post-waking.
link |
And the cutoff for when you would want to eat protein
link |
would be sometime before 10 AM.
link |
And there I'm averaging across
link |
a number of different situations.
link |
But in general, this BMAL expression is such that,
link |
let's say you wake up at 7 AM,
link |
your main interest is in hypertrophy
link |
or maintenance of muscle.
link |
Then you would want to ingest some protein
link |
sometime before 10 AM.
link |
But obviously if you're interested in getting
link |
the health effects of intermittent fasting,
link |
that you wouldn't ingest any food
link |
for at least the first 60 minutes upon waking.
link |
Now it's not as if at 1001 AM,
link |
a gate slammed shut and you can't generate hypertrophy.
link |
Of course, that's not the case.
link |
However, it's very interesting that it doesn't matter
link |
when the resistance training,
link |
the load bearing exercise occurs in the 24 hour cycle.
link |
So whether or not, in other words,
link |
people are training early in the day
link |
or they're training late in the day,
link |
it still appears that ingesting protein early in the day
link |
favors hypertrophy or that one is better,
link |
or I should say more easily able to access hypertrophy
link |
by way of these clock regulated protein synthesis mechanisms
link |
by ingesting protein early in the day.
link |
In no way, shape or form does this study say
link |
that ingesting protein later in the day
link |
is somehow bad for you.
link |
It just emphasizes the positive effects
link |
of ingesting protein early in the day
link |
for sake of muscle maintenance and or hypertrophy.
link |
So if you're somebody who's mainly concerned
link |
with muscle maintenance and hypertrophy,
link |
then it may make sense to move that feeding window
link |
earlier in the day.
link |
And certainly there are people out there
link |
who are interested in muscle maintenance and hypertrophy
link |
who aren't doing intermittent fasting at all.
link |
And that's also perfectly fine,
link |
but this just so happens to be an episode
link |
about intermittent fasting and time restricted feeding.
link |
There are of course modes of eating
link |
where one eats small meals spread throughout the day
link |
or weights meals differently,
link |
such that meals early in the day
link |
are larger than later in the day or vice versa.
link |
There are a near infinite number of ways to organize this.
link |
But if you are somebody who's interested in deriving
link |
the many clearly established health effects
link |
of time restricted feeding,
link |
and you are somebody who would like to maintain
link |
then ingesting proteins in the early part of the day
link |
would be important to you,
link |
at least on the basis of these results.
link |
And therefore that eight hour window
link |
that we've established as more or less ideal
link |
shifted to the later part of the day
link |
might not be as beneficial for you.
link |
Now, I can just personally say that for me,
link |
when I wake up in the morning,
link |
it's very easy for me to not eat until noon
link |
Eating early in the day is actually somewhat of a challenge.
link |
I discussed this point with Sachin
link |
because we were talking about
link |
how is it that one can move their feeding window
link |
or place themselves onto a different schedule
link |
of intermittent fasting.
link |
And it's very clear that one needs to provide
link |
a transition period in order for that to happen.
link |
You should allow yourself a transition period
link |
of anywhere from one week to 10 days
link |
in which you shift your feeding window
link |
by about an hour each day or so.
link |
And then once you establish a feeding window
link |
that feels comfortable for you
link |
and that you think you can maintain over time,
link |
that you simply maintain that feeding schedule
link |
for at least 30 days,
link |
but ideally you would do that indefinitely.
link |
Now, this turns out to be important
link |
based on data that they've gleaned
link |
from this my circadian clock,
link |
massive experiment that they've been doing
link |
where people are entering the times
link |
that they're feeding and eating.
link |
Excuse me, anytime we talk about mice,
link |
I always think about feeding
link |
because I come from a background
link |
and my lab works on both laboratory mice and on humans.
link |
Anytime I think about humans, I think about eating,
link |
but of course they are the same thing.
link |
The interesting thing to emerge
link |
from that very large data set in humans
link |
is that when people log their feeding times,
link |
as I mentioned before,
link |
oftentimes they think they're eating in an eight hour window
link |
but they are actually eating in a much broader window.
link |
However, even for people that are very good
link |
about restricting their feeding
link |
to a four or six or eight hour window,
link |
if they're very strict about the start and stop times
link |
when they ingest calories,
link |
one of the findings that's really been important to note
link |
is that almost every individual has a lot of drift
link |
in when that eating window resides in their 24 hour period.
link |
In particular on the weekends,
link |
people are either extending or shifting their feeding window
link |
in a way that makes it seem
link |
that they've traveled to another time zone
link |
and are eating according to another time zone.
link |
And this is extremely important.
link |
As I mentioned earlier,
link |
based on the 2012 study from Sachin's lab,
link |
we're eating at a particular phase of each 24 hour cycle
link |
can help enhance the expression of these clock genes.
link |
If you are eating within a very strict
link |
or semi-strict feeding window,
link |
but that feeding window is migrating around
link |
from day to day or five days a week,
link |
you're really organized about when that falls,
link |
let's say for sake of example,
link |
from noon to 8 PM, noon to 8 PM,
link |
Monday, noon to 8 PM, Tuesday, Wednesday,
link |
noon to 8 PM, Thursday, and so forth.
link |
But then on a Saturday, it's becoming 11 AM
link |
and you're ending it early,
link |
or perhaps you're starting early in the day on Sunday,
link |
you're having brunch that starts at nine 30 or 10,
link |
and then it's extending out still just eight hours,
link |
but it's shifting around.
link |
That can cause disruptions
link |
in these circadian clock mechanisms
link |
that cause disruptions in the downstream effects of eating
link |
that are taking at least two to three days to recover from.
link |
So obviously we don't want to be overly neurotic
link |
but because this is an episode about the science
link |
of intermittent fasting and time restricted feeding,
link |
as important as how long your feeding window is,
link |
is where that feeding window resides in each 24 hour cycle.
link |
And perhaps even more important than that
link |
is that it be fairly regular
link |
where that feeding window resides,
link |
because even if you have a very short feeding window,
link |
if it's drifting around from day to day,
link |
that actually offsets a number
link |
of the positive health effects of intermittent fasting.
link |
So to really just underscore the way
link |
that these different pieces
link |
of the biological puzzle fit together,
link |
if you are very strict or semi-strict
link |
about your eight hour feeding window,
link |
but on the weekends that eight hour feeding window
link |
is falling later than it normally would
link |
during the middle of the week,
link |
it is as if you are going to bed later,
link |
even if you're going to bed at the same time,
link |
at least from the perspective of metabolic health,
link |
because of the way that eating impacts these clock genes
link |
and impacts, or I should say,
link |
subtracts the sleep related fasting
link |
that you would normally experience
link |
if you were to finish eating
link |
a couple hours before bedtime.
link |
So again, we don't want to create any overly obsessive
link |
or neurotic focus on this.
link |
I think that most all people could benefit
link |
from a time-restricted feeding schedule,
link |
but they should really think hard
link |
about what they can stick to on a regular basis
link |
and understand that they tend to underestimate
link |
the feeding window that they actually are partaking in,
link |
and that they should place that feeding window
link |
in a portion of the 24 hour cycle
link |
that they can be consistent on most days.
link |
And I want to emphasize most,
link |
again, because we are not laboratory mice.
link |
We don't have a graduate student
link |
coming in for eight hours a day
link |
because that's what their significant other
link |
will allow them to do.
link |
And then removing the food from our jowls
link |
and from our cages,
link |
we have access to food pretty much 24 hours a day.
link |
Along those lines, however,
link |
there are things that we can all do
link |
that will allow us to offset some of the drift,
link |
if you will, that we experience
link |
or that we induce in terms of
link |
when our feeding window occurs
link |
or that the feeding window might push out a little later
link |
and then therefore start a little later the next day.
link |
There are things that we can do
link |
and there are things that we can take.
link |
And so I'd like to discuss those briefly.
link |
So throughout this episode,
link |
I've more or less been alluding to the fact
link |
that when you eat,
link |
there's some period of time afterwards
link |
in which you're actually still eating,
link |
at least from the perspective of metabolism,
link |
because glucose is up, insulin is up,
link |
and you're undergoing different metabolic
link |
and digestive processes that don't really speak to you
link |
being in a fasted state, right?
link |
It's not just about when you take your last bite
link |
However, there are things that we can do
link |
to accelerate the transition from a fed state
link |
to a fasted state.
link |
And so I'd like to discuss what those are.
link |
And I want to emphasize that the term fed state
link |
is probably a better way to think about it
link |
than eating or not eating,
link |
because we think of eating as the verb,
link |
we're eating, we're eating, okay, we're done eating,
link |
but you're not actually fasting because you are fed.
link |
So we should really think about fed and unfed states
link |
because from a cellular processes perspective
link |
and from a health perspective,
link |
that's actually what your body and your system
link |
are paying attention to.
link |
And by now with everything that we've laid out,
link |
I think that should be intuitive to understand.
link |
So there's a fun and exciting concept related to this,
link |
which is glucose clearing.
link |
You may have heard the old adage
link |
that if you take a 20 or 30 minute walk after dinner,
link |
that it accelerates the rate at which you digest that food.
link |
And indeed it does.
link |
Clearing out of glucose from your system
link |
can be accomplished through a number of different means,
link |
but light movement or exercise
link |
does increase gastric emptying time.
link |
if you were to eat a meal that ended at 8 PM
link |
and then plop to the couch, watch TV,
link |
or get on your computer or go to sleep,
link |
it would be five or six hours until you have transitioned
link |
from a fed state to a fasted state.
link |
However, you can accelerate that considerably
link |
by taking a 20 or 30 minute, just light walk.
link |
It doesn't have to be speed walking.
link |
It certainly doesn't have to be jogging,
link |
but just walking outside or moving around.
link |
So glucose clearing is an important aspect of the transition
link |
from the fed state to the fasted state.
link |
And just a light walk can allow you to do that.
link |
Now, if you can't get outside,
link |
some people will go through the gymnastics literally
link |
of doing things like air squats and pushups
link |
and things like that.
link |
And indeed those will increase the expression of things
link |
like Glut4 and things that mobilize glucose into muscles
link |
and things of that sort.
link |
But, you know, under most conditions,
link |
most people aren't doing pushups after dinner,
link |
or certainly if you've had a big meal,
link |
just taking a light walk can be beneficial.
link |
In addition, you could consider doing intense exercise.
link |
Now you wouldn't necessarily want to do that
link |
immediately after eating.
link |
So let's take a look at what high intensity training
link |
of any kind does to blood glucose,
link |
because in this case,
link |
it turns out that when you do high intensity training
link |
actually has opposite effects on blood glucose,
link |
depending on whether or not you do it
link |
early or later in the day.
link |
So a fairly recent study looked at so-called HIIT training,
link |
high intensity interval training,
link |
which of course can take many different forms.
link |
It can take the form of circuit training with weights.
link |
It can take the form of, you know, burpees and pushups
link |
and sprints and all sorts of different things,
link |
but high intensity interval training is typically training
link |
that gets people's heart rates up, you know,
link |
well above 70% of maximum and then brief periods of rest
link |
and then repeating and how long the high intensity interval
link |
training of course will also vary.
link |
There are very brief, you know,
link |
six or 12 or 15 minute workouts.
link |
Some people can carry on with high intensity interval
link |
training for up to 45 or maybe even 60 minutes
link |
But when you look at the studies that have explored high
link |
intensity interval training and its effect on blood glucose,
link |
there are a couple of studies that leap out.
link |
one that emphasize that blood glucose levels will actually
link |
increase if high intensity interval training is performed
link |
early in the day and will decrease if high intensity
link |
interval training is performed later in the day.
link |
Now the purpose for this exploration was not to explore
link |
clearance of blood glucose for sake of intermittent
link |
It was mainly focused on athletic performance and whether
link |
or not that was better early in the day or later in the day,
link |
But we can extract some information from these studies that
link |
are beneficial for sake of understanding glucose clearing.
link |
If you have ingested food throughout the afternoon and
link |
evening and late in the day,
link |
and you're thinking about going to sleep and you'd like to
link |
enter sleep in a way that is less fed and more fasted,
link |
then engaging in high intensity interval training in the
link |
afternoon will lower or evening,
link |
I should say will lower blood glucose.
link |
And in that way will help you accelerate your transition
link |
into the fastest state provided you don't ingest something
link |
after the high intensity interval training.
link |
Now is the increase in blood glucose that occurs from high
link |
intensity interval training early in the day,
link |
is that detrimental?
link |
Not necessarily so that oftentimes is associated with the
link |
shuttling of nutrients to the muscles that have just done a
link |
So it's not that high intensity interval training should not
link |
be done early in the day.
link |
In fact, for many people,
link |
including myself training early in the day,
link |
just for the way that my psychology and biology works is
link |
always better for me than training later in the day.
link |
And the other important thing to mention is that high
link |
intensity interval training done late in the day can be
link |
beneficial from the perspective of glucose clearing,
link |
lowering blood glucose and helping transition from the fed
link |
to the fasted state in preparation for sleep.
link |
However, if you're ingesting caffeine or anything to engage
link |
in that high intensity interval training in a way that
link |
prevents you from getting to sleep, well,
link |
then it's going to be detrimental overall.
link |
So the reason I mentioned this is of course,
link |
because it's nice to know that light walks after dinner or
link |
any other meal for that matter or high intensity interval
link |
training provided it's done in the second half of the day,
link |
can lower blood glucose and speed the transition from fed to
link |
But I also mention it because what we are really trying to
link |
achieve when we partake in intermittent fasting,
link |
so-called time restricted feeding is what we're really
link |
trying to do is access unfed states or fasted states.
link |
It's not really about when you eat and what you do.
link |
It's about extending the duration of the fasting period,
link |
as long as you can,
link |
in a way that's still compatible with your eating, right?
link |
Not the other way around.
link |
And this gets back to this key feature of our biology,
link |
which is that what we eat, when we eat, when we exercise,
link |
when we view light,
link |
it's about setting a context or a set of conditions in your
link |
So it's not so much about the activities that you undergo.
link |
It's about the activities you undergo and their
link |
relationship to one another over time.
link |
And so in this way,
link |
it really beautifully highlights the way that your biology is
link |
interacting all the time.
link |
Light is setting when you're going to be awake and when
link |
you're going to be asleep,
link |
when you eat is going to be determining when you're going to
link |
be awake and when you're going to be asleep and when you eat
link |
is also going to be determining when you are able to clear
link |
out debris from your brain and body and repair the various
link |
cells and mechanisms of your body,
link |
when you're able to reduce those inflammatory cytokines
link |
throughout your body.
link |
And this is really the beauty of time-restricted feeding,
link |
which is it's not really about restricting your feeding.
link |
It's about accessing the beauty of the fasted state.
link |
Now, there are other ways to clear out blood glucose that
link |
involve supplements or prescription drugs.
link |
These are so-called glucose disposal agents,
link |
glucose disposal agents, such as metformin,
link |
which is a prescription drug or berberine,
link |
which is an over the counter substance will lead to very
link |
dramatic reductions in blood glucose.
link |
And so they shift you from a fed to a fasted state.
link |
And I know many people who take berberine before eating
link |
meals that include a large number of carbohydrates,
link |
for instance, as a way to clear out glucose.
link |
Now I've tried berberine before.
link |
And what I can tell you is that if you take berberine,
link |
which by the way is very much like metformin,
link |
its effects are almost identical to metformin in fact,
link |
but it's much less expensive and it's over the counter.
link |
If you take berberine and you have not ingested
link |
carbohydrates, many people, including myself,
link |
experience a splitting headache.
link |
You become hypoglycemic because it is a glucose clearing
link |
So if you're going to experiment with things like metformin
link |
and or berberine or similar,
link |
you want to be very cautious that you're not clearing out
link |
blood glucose that's already low.
link |
And the dose response for this varies tremendously from one
link |
individual to the next.
link |
And there's a strong circadian component.
link |
So some people react very well to berberine early in the
link |
day, but find that later in the day,
link |
it provides extreme headaches for some people,
link |
it's the opposite.
link |
So I caution you in exploring things like berberine and
link |
metformin that you should expect to experience a number of
link |
physical and psychological effects that may work for you,
link |
might be great for you, but might also not be great for you.
link |
there are a number of commercially available continuous
link |
I've tried one of these.
link |
It involves putting what's essentially a patch with a little
link |
needle that goes into your skin,
link |
which is continuing continually, excuse me,
link |
monitoring your blood glucose.
link |
And you can look at it at an app on your phone.
link |
And you can learn a lot that way about how different foods
link |
impact the increases and decrease in blood glucose.
link |
If you're doing experiments with berberine or metformin,
link |
you can see how those impact your blood glucose.
link |
You can see how exercise hit training or otherwise impact
link |
impacts blood glucose.
link |
It's very hard to assess blood glucose without a continuous
link |
blood glucose monitor.
link |
And if you're not using one,
link |
you're mainly going to be relying on subjective things like,
link |
oh, I feel like I have low blood sugar.
link |
Like I have high blood sugar or shaky.
link |
Cause you have low blood sugar.
link |
So I have to say that glucose clearing agents that involve
link |
a walk or exercise moderate or intense are going to be a lot
link |
easier to titrate and adjust the levels of than things that
link |
you're going to take where you have to ingest the dosage.
link |
And then once you ingest a certain dosage,
link |
you're along for the ride,
link |
at least until the effects of that particular compound wear
link |
off, it doesn't mean those things don't have utility.
link |
It doesn't mean people aren't using them because many
link |
but they are potentially a very sharp blade.
link |
That is a double sided blade.
link |
So I encourage you to approach those with caution.
link |
If you decide to at all,
link |
it's worth thinking about what the low blood glucose state
link |
is and why it's beneficial as well as why it might produce
link |
And in some cases can also adjust the effects of other
link |
hormones in the fasted state.
link |
A number of different proteins that are expressed in cells
link |
undergo changes in their expression.
link |
We talked about this earlier.
link |
When we are fasted,
link |
we tend to reduce the activity of a particular protein
link |
called mTOR mammalian target of rapamycin mTOR is very
link |
active in cells while they are growing.
link |
So throughout development,
link |
it's also very active in cancers of various kinds.
link |
mTOR needs to be what's called phosphorylated.
link |
If you don't know what that means, don't worry about it.
link |
But phosphorylation is a manner in which certain proteins
link |
are altered so that they can actually be functional within
link |
mTOR is associated with cell growth of all kinds,
link |
healthy and unhealthy.
link |
When mTOR is phosphorylated, there's a marker called PS6.
link |
So phospho mTOR expresses PS6.
link |
If this is all escaping you, don't worry about it.
link |
Phospho mTOR and PS6 are reduced by fasting.
link |
Now this makes sense if you think about it,
link |
because eating and growth are associated with each other.
link |
Fasting is not necessarily anti-growth,
link |
but it is not pro-growth.
link |
And when we fast, we see increases in cells of things like
link |
AMPK, the sirtuins, things like transcription factors,
link |
like FOXO, ATF and ketones or ketone bodies.
link |
You may have heard of the ketogenic diet.
link |
What's the point of all this biochemistry.
link |
It's not to just blitz you with a bunch of cellular biology
link |
It's to say that we have cell growth pathways involving
link |
mTOR and PS6, and we have cell repair
link |
and cell shrinkage processes that are associated with AMPK,
link |
the so-called sirtuins,
link |
which Dr. David Sinclair from Harvard and others are famous
link |
for discovering and understanding things like AMPK.
link |
These two different divergent pathways of cell growth
link |
and cell breakdown and repair.
link |
And by breakdown, I mean actual clearance,
link |
autophagy and repair.
link |
Those can be triggered by being in either the fed
link |
or the fasted state.
link |
So one way I'd like you to think about the fed state,
link |
not just eating, but having recently eaten
link |
or the fasted state, meaning high blood glucose
link |
and or you've recently eaten or are currently eating
link |
or drinking calories is that when you eat
link |
or when you don't eat, when you're fed,
link |
when you're fasted,
link |
you are either promoting cellular growth of all kinds
link |
or you're promoting cellular repair
link |
and clearance of all kinds.
link |
And so, again, this is about setting conditions
link |
in the brain and body.
link |
It's not so much about when you eat food A or B,
link |
it leads to increases in mTOR.
link |
Anytime you eat any food,
link |
doesn't matter if it's plant-based, animal-based, fat,
link |
protein, carbohydrate, doesn't matter.
link |
You are biasing your system towards a biochemical state
link |
And anytime you haven't eaten for a while
link |
or blood glucose is low,
link |
you're biasing your system toward a state of cellular repair.
link |
And this is why people who do not suffer
link |
from any blood glucose regulation issues,
link |
take things like berberine as glucose disposal agents
link |
or take metformin.
link |
I'm not necessarily suggesting that you do that,
link |
but it's because those things mimic fasting.
link |
They create situations in the body that promote things
link |
like AMPK and the sirtuins and others to push your body
link |
and your system down a route of repair,
link |
even though you might've just eaten a meal an hour ago.
link |
Along the lines of the health benefits
link |
of intermittent fasting,
link |
there are nice data showing improvements
link |
in the gut microbiome.
link |
And in particular,
link |
in the treatment of irritable bowel syndrome
link |
and other forms of colitis in time-restricted feeding,
link |
meaning time-restricted feeding seems to be able
link |
to assist people with those conditions
link |
following the general parameters that I discussed before,
link |
eight hours and so forth.
link |
Well, by way of intermittent fasting,
link |
impacting the expression of these various clock genes
link |
and because the clock genes impact the mucosal lining,
link |
the mucus lining of the gut,
link |
it appears that intermittent fasting
link |
can reduce the amount of so-called lactobacillus
link |
that's present in the gut.
link |
And lactobacillus is when in high levels is correlated
link |
with a number of different metabolic disorders.
link |
time-restricted feeding seems to enhance the proliferation
link |
of some of the gut microbiota like oscillobacter
link |
and some of the other ones
link |
that promote healthy mucosal lining
link |
and that promote better overall intestinal function.
link |
So these are pathways that have now been established
link |
and it appears that intermittent fasting
link |
isn't just modulating these processes,
link |
but is actually having a direct effect
link |
on the mucosal lining in a way
link |
that favors a healthier gut microbiome.
link |
So it should come as no surprise
link |
that many people who experience gut issues benefit
link |
from restricting their feeding window
link |
to eight hours or so per every 24 hour period.
link |
The other very exciting finding about intermittent fasting
link |
is one of the major health issues these days
link |
is the proliferation of so-called
link |
non-alcoholic fatty liver disease.
link |
30 years or so non-alcoholic fatty liver disease
link |
was exceedingly rare to see in the clinic,
link |
except in alcoholics.
link |
Fatty deposits in the liver are bad.
link |
It is essentially liver disease.
link |
Nowadays, children and adults are showing up
link |
with non-alcoholic fatty liver disease.
link |
Some of these people are obese, others are not,
link |
but it's a serious health concern
link |
and it's growing in numbers all the time.
link |
A recent study that was published in Cell Reports Medicine
link |
just a couple of weeks ago tested the hypothesis
link |
whether or not the gut microbiome
link |
or so-called brown fat tissue is impacting the liver health
link |
and in particular non-alcoholic fatty liver disease.
link |
The short takeaway from this study is that
link |
contrary to what was previously thought,
link |
the gut microbiome, while very important
link |
for a number of other processes in the body,
link |
doesn't seem to be related
link |
to this non-alcoholic fatty liver disease.
link |
This is surprising to people or should be
link |
to those of you that have been following
link |
the gut microbiome literature.
link |
However, brown fat, which is a healthy fat
link |
that we have between our two scapulae and in our upper neck,
link |
it doesn't tend to be blubbery type fat pads,
link |
but it sits deep to the skin,
link |
but creates a thermogenic effect in the body
link |
that is helpful for reducing the amount of other fat,
link |
the type of fat that we're more typically used to thinking
link |
about and talking about white fat and pink fat
link |
that's subcutaneous fat around the abdomen and so forth.
link |
Brown fat seems to have a direct correlation
link |
with the lack of non-alcoholic fatty liver disease.
link |
What this study showed was that
link |
in people that have diminished concentrations of brown fat,
link |
there is a higher probability
link |
of having non-alcoholic fatty liver disease.
link |
Now, the good news is brown fat stores can be increased.
link |
And again, this isn't going to create blubber of brown fat.
link |
This is going to create increased thermogenesis
link |
and actually make people leaner.
link |
And brown fat has a number
link |
of other important positive effects.
link |
Now, this is interesting because cold exposure
link |
of anywhere from one to three minutes,
link |
two or four times per week, or maybe even 10 minutes,
link |
two to four times per week can increase brown fat stores.
link |
Also time-restricted feeding has now been tied
link |
to the density of brown fat stores.
link |
So time-restricted feeding also seems
link |
to positively increase brown fat stores,
link |
probably because of the way that brown fat stores relate
link |
to epinephrine and adrenaline,
link |
which tend to go up when we're fasted.
link |
What does this all mean?
link |
This means for sake of liver health
link |
and for sake of reducing or maybe preventing
link |
or even potentially,
link |
want to underline potentially reversing
link |
non-alcoholic fatty liver disease,
link |
time-restricted feeding also appears to be beneficial.
link |
Many people out there are interested
link |
in optimizing their hormones.
link |
And as we mentioned earlier, insulin is a hormone
link |
and time-restricted feeding seems
link |
to have very positive effects
link |
on overall insulin profiles and so forth.
link |
But anytime you mention hormones,
link |
people immediately seem to leap to the sex steroid hormones,
link |
testosterone and estrogen,
link |
because indeed they have powerful effects,
link |
both in the short-term and the long-term in terms
link |
of our mental and physical health and performance.
link |
There's at least one study that's explored the effects
link |
of time-restricted eating on performance,
link |
athletic performance, immune function,
link |
and body composition.
link |
This was a study by Morrow et al
link |
that was performed on elite cyclists.
link |
So I want to point that out.
link |
It was a randomized control trial,
link |
but what's really nice about this study is
link |
that it explored a number of different hormonal parameters
link |
in people that were using time-restricted eating
link |
or that had a more extended eating window.
link |
And they tracked everything very carefully.
link |
And the amount of food they were eating
link |
was actually pretty considerable, 4,800 calories.
link |
So that's a lot of calories,
link |
but then again, they were very active.
link |
And they've measured a number
link |
of different things related to VO2 max, et cetera.
link |
Performance and overall performance at what they did,
link |
cycling is not the point that I want to emphasize here.
link |
Although there were some positive effects
link |
on their performance related to time-restricted eating.
link |
The point I want to talk about relates to things
link |
that presumably relate to most everybody,
link |
which are the effects on things like glucose,
link |
thyroid hormone, testosterone,
link |
sex hormone binding globulin,
link |
which can bind up testosterone and prevent
link |
the so-called free form of testosterone,
link |
which is the one that has most of the actions
link |
in the brain and body.
link |
And the major takeaway from this study
link |
was that time-restricted feeding
link |
of the same amount of calories
link |
as the so-called control condition, okay?
link |
Same calories, but either compact
link |
throughout the 24 hour cycle to an eight hour feeding window
link |
or allowing them to eat over a larger feeding window
link |
did lead to significant decreases in free testosterone.
link |
And I think a number of people will raise their eyebrows
link |
to that and think, oh,
link |
well then maybe time-restricted feeding is not for me.
link |
There are a number of important considerations, of course.
link |
One is while the decrease in free testosterone
link |
it's also going to depend on where people start out.
link |
So if somebody has already low or modest levels
link |
of testosterone and it drops by 10 or 20%,
link |
that could lead them into a state of poor performance
link |
Whereas if somebody has higher testosterone,
link |
a decrease won't necessarily do that.
link |
So it's important to take that into consideration.
link |
This is why I'm always such a fan
link |
of people doing their blood work
link |
and knowing what's going on under the hood for them.
link |
A very interesting change in hormonal profile
link |
was cortisol, so-called stress hormone.
link |
Cortisol, of course,
link |
is also naturally released early in the day
link |
in a healthy way to wake you up and promote alertness,
link |
but you don't want its levels to be too high
link |
or to have peaks in cortisol late in the day.
link |
It's actually correlated with depression
link |
and a number of other untoward things.
link |
I would have thought that by restricting a feeding window
link |
to a particular time each day,
link |
that these hard training cyclists
link |
would have undergone increases in serum cortisol.
link |
And in fact, the opposite was true.
link |
They had significant reductions in serum cortisol
link |
as a consequence of time-restricted feeding.
link |
I should mention there were significant reductions
link |
in serum cortisol also in the control group,
link |
but not to the same extent.
link |
And the two groups did differ significantly
link |
Now, this is important because if you just look
link |
at one hormone, testosterone, you'd say,
link |
okay, based on these data, time-restricted feeding
link |
is reducing testosterone levels significantly,
link |
even though the number of calories is quite high
link |
and is held constant across the study.
link |
But in fact, because cortisol is lower,
link |
it may mean that the effects of testosterone
link |
or the reduction in testosterone is offset.
link |
And that's because cortisol and testosterone
link |
are always in this somewhat of a dance
link |
in terms of cortisol inhibiting the effects
link |
of testosterone largely and vice versa.
link |
So it is interesting and important
link |
to look at the total gallery of hormones.
link |
And they did look at a number of hormones.
link |
They looked at other inflammatory markers.
link |
Those were not increased.
link |
That's not surprising.
link |
If you remember back to the 2012 Sachin Panda study,
link |
this early pioneering study on time-restricted feeding,
link |
they saw reductions in stress hormones
link |
and in inflammatory markers
link |
in time-restricted feeding mice.
link |
And here, this also seems to be the case in humans.
link |
So the takeaway is for sake of hormone health,
link |
time-restricted feeding is compatible
link |
with quality hormone health,
link |
even in high-performing athletes.
link |
Based on everything we know and that we've discussed,
link |
I would not suggest that people restrict
link |
their feeding window to less than eight hours,
link |
especially if they're training hard on a regular basis.
link |
And it's not just athletes that should pay attention to this
link |
when we are working very hard,
link |
when we are psychologically stressed,
link |
when we are studying for exams,
link |
or we are in conflict with somebody on a regular basis,
link |
that creates a stress in the body
link |
that's very similar to that of physical training.
link |
The body and brain don't distinguish
link |
between physical stress and mental stress.
link |
It's all nervous system.
link |
Remember that it's just cortisol and adrenaline.
link |
There's no special hormone just for physical stress
link |
versus psychological stress.
link |
So again, in thinking about what sort of feeding window
link |
will be right for you,
link |
we arrive back at this eight-hour time bin
link |
that seems more or less flexible for most conditions,
link |
even high-performing elite athletes.
link |
And I would say just by logical extension,
link |
even for people that have a lot of stress in their life.
link |
And I personally wouldn't suggest
link |
that people who have a lot of stress in their life
link |
or the potential for stress in their life
link |
shorten their feeding window much shorter than eight hours,
link |
because then you would expect
link |
that you would start to increase
link |
some of the inflammatory markers.
link |
You would increase the stress hormones
link |
and you would be decreasing things like testosterone
link |
and estrogen and some of the sex steroid hormones.
link |
So again, it's all about context and the eight-hour window.
link |
It isn't holy, but seems to be a really useful guide
link |
to extract the great health benefits
link |
of which there are many and of which we've discussed
link |
from intermittent fasting, time-restricted feeding,
link |
and yet that it could still be compatible
link |
with decent social schedules
link |
and for maintaining hormone health.
link |
In keeping with this,
link |
for women that are trying to maintain ovulatory cycles
link |
or for couples that are trying to get pregnant,
link |
I think it's also important
link |
to not create a feeding window that's too short.
link |
The relationship between feeding and body fat stores
link |
and glucose and leptin and hormones
link |
is a well-established one.
link |
And we can summarize it very easily here,
link |
although I've done several episodes
link |
related to this previously on optimizing hormone health.
link |
But basically, we undergo puberty
link |
when there's enough food and there's enough body fat
link |
that the body fat sends a signal to the brain called leptin,
link |
that's a hormone that comes from body fat,
link |
signals to the brain to turn on puberty.
link |
That's puberty, but even as adults,
link |
for women that are menstruating,
link |
there needs to be sufficient leptin signaling to the brain
link |
in order to maintain ovulation
link |
because of the way that the brain communicates
link |
with the pituitary and the ovaries.
link |
Similarly, for men,
link |
fasting or extreme exercise plus fasting,
link |
we now know reduces testosterone.
link |
Its impacts are not exactly clear.
link |
However, if you reduce food intake,
link |
either in total calories or in duration too much,
link |
you will suffer a drop in sperm counts, fertility will drop.
link |
And this makes sense.
link |
The body is communicating to the brain
link |
whether or not conditions are sufficient in the body
link |
to reproduce and to presumably and hopefully support
link |
the health and wellbeing of those offspring.
link |
So there's a logical link between body fat and eating
link |
and how much food is available to you
link |
and how long it's available to you
link |
and the signals in the brain
link |
that allow for reproductive success.
link |
There are some data that pointed differences
link |
in the effects of intermittent fasting
link |
for males versus females.
link |
Those data right now only come from mice.
link |
That study was published by Sachin Panda recently.
link |
We still await the studies in humans.
link |
Some people do not do well on intermittent fasting,
link |
either in terms of mood or hormone health.
link |
And so everyone needs to determine for themselves
link |
whether or not having a time-restricted feeding window
link |
how long that time-restricted feeding window should be.
link |
I think eight hours is kind of a nice minimum to adhere to
link |
based on everything that we've covered today.
link |
And for some people,
link |
time-restricted feeding is not going to be compatible
link |
with hormone health for them.
link |
For them, eating more meals spread throughout the day,
link |
presumably smaller meals, same caloric intake,
link |
is going to be more beneficial for their hormones.
link |
This is something that is going to be individual
link |
and is going to have to be determined
link |
on an individual basis.
link |
However, if you're going to try time-restricted feeding,
link |
I do want to remind you that taking a period of three to seven
link |
or ideally 10 days to transition into it,
link |
not just going flipping from eating to three meals a day
link |
that span from 6 a.m. to 10 p.m.
link |
and suddenly going to an eight-hour feeding window,
link |
but rather winnowing down that feeding window
link |
about an hour or so per day
link |
is going to allow the hormone systems of your body,
link |
including leptin, the hypocretin-erexin system,
link |
which are systems within the body that signal to the brain
link |
that food is about to come,
link |
allowing those systems to adjust
link |
so that you're not overwhelmingly hungry, irritable,
link |
and you're not throwing your whole hormone system
link |
I keep coming back to this eight-hour feeding window
link |
and I want to provide a little more basis for it
link |
and just to encourage that it's not completely arbitrary.
link |
The lengthy review that I mentioned earlier
link |
features a number of studies
link |
that have used this eight-hour feeding window.
link |
But there's a particular study that I'd like to highlight,
link |
mainly because I don't expect people to delve
link |
into the full reference list of the other review.
link |
And this is a study that was carried out
link |
between Sachin Panda's lab and Christopher Verity's lab.
link |
So this is a collaboration.
link |
The study was carried out in humans
link |
and is entitled effects of eight-hour time-restricted feeding
link |
on body weight and metabolic disease risk factors
link |
in obese adults, excuse me.
link |
And this study essentially showed,
link |
I'll just read the conclusions,
link |
that an eight-hour time-restricted feeding
link |
produces a mild caloric restriction and weight loss
link |
without calorie counting.
link |
So that's key, right?
link |
These people aren't calorie counting.
link |
Somehow just by adhering to an eight-hour window,
link |
they are taking in fewer calories than they're burning off
link |
and clinically it reduced blood pressure.
link |
So I mentioned the study,
link |
not because there aren't many others
link |
involving the eight-hour feeding window, also in humans,
link |
but because the eight-hour feeding window has been tested
link |
in obese adults and non-obese adults.
link |
And there are even a few studies in children.
link |
So this eight-hour window seems to be
link |
a really good rule of thumb and a kind of anchor
link |
around which we can each think about
link |
incorporating time-restricted feeding.
link |
There are, of course, other patterns of feeding.
link |
And while some people have engaged in longer fasts
link |
of 24 hours, 36 hours, or more,
link |
alternate day fasting, meaning eating one day,
link |
not eating the next day, or in some cases eating one day
link |
and eating very few calories,
link |
500 or 600 calories the next day, has been tested.
link |
A few studies have also looked at eating
link |
a sort of maintenance level of calories for five days
link |
and then taking two days and fasting clear through
link |
or eating very few calories, 300 or 500 calories.
link |
In fact, there's a sort of a community online
link |
of people that are exploring longer fasts
link |
for sake of trying to offset dementia
link |
or reverse effects of dementia.
link |
Thus far, at least in my awareness,
link |
there isn't any quality clinical peer-reviewed study
link |
on that yet for sake of dementia.
link |
Although I await those studies
link |
and if anyone's aware of them,
link |
please send me a link in the comments.
link |
But alternate day fasting has gotten
link |
the so-called safe bill of health.
link |
This has been written up,
link |
meaning that people didn't suffer bone loss.
link |
They didn't suffer any major detrimental effects.
link |
It does seem that it can create significant weight loss
link |
and can help with obese individuals,
link |
that it can reduce resting blood glucose.
link |
And every other day fasting, in many cases,
link |
can produce more rapid effects on weight loss
link |
and reductions in blood glucose than time-restricted feeding.
link |
However, every other day type fasting,
link |
for most people, is not going to be feasible.
link |
They're just not going to be able to do that
link |
for a long period of time.
link |
And what hasn't really been done is the follow-up,
link |
to see whether or not people who do every other day fasting
link |
or five days of eating followed by two days of fasting,
link |
whether or not that leads to a rebound in weight gain,
link |
whether or not that leads to a rebound
link |
in blood glucose, et cetera.
link |
So for now, the eight-hour feeding window
link |
and time-restricted feeding seems to be the most tested,
link |
supported in animal studies and in human studies,
link |
and the one around which I think most people should orient
link |
if they're considering getting into time-restricted feeding.
link |
It's also sort of hard to imagine how one could include
link |
a significant exercise schedule or work schedule
link |
on every other day fasting.
link |
Remember, in any study, people are often being compensated,
link |
or at least are incentivized in some way
link |
to adhere to the study.
link |
This is one of the major issues that I have with any study
link |
that says that three or four different diets
link |
are essentially equal in terms of their ability
link |
to produce weight loss.
link |
Adherence is very different in the outside world,
link |
where you don't have a researcher monitoring you,
link |
where you're not logging all your food.
link |
Most people don't do that consistently.
link |
And we can take a little bit of a neuroscience perspective
link |
on this to try and arrive at what the best kind
link |
of organization of an eating plan, or if we wanted
link |
to call it a diet, we could, would be for you.
link |
Many people find it easier to just not eat
link |
for certain periods of each 24-hour cycle
link |
than to eat smaller portions.
link |
Portion control is very hard for some people.
link |
For other people, it's manageable.
link |
But people like me, I don't eat half the croissant.
link |
I don't think it's a real thing.
link |
It's not available to me, I should say.
link |
Now, of course I could eat just half a croissant.
link |
But I noticed that when I eat the croissant,
link |
because they're so delicious,
link |
that it creates a rise in blood glucose,
link |
a rise in the other hormones and chemicals
link |
that are associated with ingesting delicious,
link |
highly palatable food.
link |
And it's actually a lot of work for me
link |
to just eat half the croissant.
link |
There's something that's much more thoroughly satisfying
link |
about eating the entire croissant.
link |
And actually, there's something that's somewhat satisfying
link |
about not eating the croissant at all,
link |
and just knowing that later I can eat the whole croissant.
link |
Other people find that they don't have any trouble
link |
with portion control.
link |
That for them, just eating small bits of food
link |
throughout the day is what sets them
link |
in the right psychological and physical state
link |
for sake of work, et cetera.
link |
And I mentioned work and mental focus
link |
because one of the aspects of fasting
link |
that have drawn a lot of people
link |
to time-restricted feeding and fasting
link |
is the clarity of mind that people get
link |
when, first of all, they don't have to think about
link |
when they're going to eat
link |
because they know when their eating window begins.
link |
They also don't have to think about regulating
link |
their behavior because they already know
link |
when they're going to eat and when they're not going to eat.
link |
Whereas when you're restricting portions,
link |
you actually have to make decisions all the while.
link |
You know, and I think I, like many people decide,
link |
well, you know, is that exactly half
link |
or could I have like another rung on the croissant,
link |
this kind of thing.
link |
I don't negotiate with food.
link |
That's why I like a time-restricted feeding window.
link |
I know I'm going to eat for, in my case,
link |
I use a 10-hour feeding window or so.
link |
And I'll eat the whole croissant.
link |
I just don't have to think about it.
link |
Now, the food choices that you make
link |
inside of that feeding window are of course
link |
also going to be very important.
link |
Certain foods will increase blood glucose
link |
such that you're going to get hungrier and hungrier.
link |
Others will maintain lower blood glucose
link |
and will allow you to be more controlled
link |
in the foods that you pursue.
link |
Those are all individual considerations
link |
that are deserving of their own entire episode.
link |
But I do want to point out that the advantage
link |
of time-restricted feeding is that it involves
link |
a lot of the decision-making in the brain,
link |
the so-called go, no-go circuitries of our basal ganglia,
link |
if you want to know those areas that control them.
link |
Anytime we have to restrict a behavior,
link |
that's called a no-go.
link |
Anytime we engage in a behavior, that's a go.
link |
No-go behaviors require a lot of what's called
link |
top-down control, and it's very metabolically demanding.
link |
And so time-restricted feeding allows you to depart
link |
from the whole no-go, go negotiation
link |
that you have to undergo when you have to restrict portions.
link |
And so I think this is a reason why many people
link |
have gravitated towards time-restricted feeding
link |
and why for people that don't want to have to think
link |
about all that, it's just very straightforward.
link |
One of the more hot button issues out there
link |
is whether or not given equal amounts of caloric intake
link |
and equal amounts of activity
link |
and equal amounts of nutrients, et cetera,
link |
whether or not restricting food to a particular window
link |
biases more weight loss toward fat loss
link |
versus loss of other tissues.
link |
Because of course, when we lose weight,
link |
we can lose that from any number of different
link |
storage sites within the body, muscle, water,
link |
Now, this is such a hot button issue
link |
that I almost don't want to get into it,
link |
but I'm going to get into it anyway,
link |
because there are data that are very interesting.
link |
This is covered in the review that I mentioned earlier
link |
that describes how if people follow
link |
a time-restricted feeding schedule for long periods of time,
link |
so 60 days or longer, there are some metabolic changes
link |
in the way that people metabolize energy
link |
that do seem to shift the system toward more fat loss
link |
relative to burning of other tissues
link |
when in a state of caloric restriction.
link |
And I want to say when in a state of caloric restriction,
link |
because there's really no way to cheat the system.
link |
There's no way that you can ingest far more calories
link |
than you burn or excrete.
link |
When I say excrete, you know, I certainly don't suggest this,
link |
but there, you know, bulimics and other people
link |
that have eating disorders will use laxatives
link |
as a way to eliminate food quickly from their system
link |
so it can't be converted into fat or other forms of energy.
link |
That's a very, in that case, it's a pathological situation,
link |
but in general, calories in versus calories out,
link |
as I mentioned earlier, is this kind of foundational element
link |
but in states of caloric restriction,
link |
meaning sub-maintenance intake,
link |
time restricted feeding does seem to bias
link |
more of the energy burned to compensate
link |
for that deficit from fat.
link |
And the way it accomplishes it is very interesting.
link |
It turns out that it drives more fat loss
link |
by way of increasing a hepatic lipase.
link |
This is something called LIPC,
link |
hepatic means of the liver and lipase,
link |
which anytime you hear ASE is means it's an enzyme.
link |
So it seems to increase hepatic lipase.
link |
So it increases the enzyme that metabolizes fat
link |
for lipolysis and energy production
link |
and reduces something called CIDEC, C-I-D-E-C,
link |
which is a lipid droplet associated and lipolysis inhibitor.
link |
Now that's a mouthful, no pun intended,
link |
but what CIDEC really is,
link |
this lipid droplet associated molecule
link |
is it can inhibit lipolysis.
link |
So extended periods of time restricted feeding,
link |
meaning eight hour feeding window or 10 hour feeding window
link |
that's obeyed for several months or more
link |
seems to allow the system to shift toward burning more fat
link |
or rather using a higher percentage of fat
link |
when in a caloric deficit.
link |
Now, I doubt that this is going to resolve
link |
the truly barbed wire,
link |
almost hairball ridiculous online debates
link |
about whether or not time restricted feeding
link |
is better than another feeding schedule.
link |
Look, I don't think any particular feeding schedule
link |
If you are sub caloric,
link |
meaning fewer calories burned than calories ingested,
link |
you're going to lose weight.
link |
But the data seemed to point to the fact
link |
that if you do time restricted feeding
link |
for a fairly long duration of time,
link |
and you maintain that,
link |
that you are increasing these lipases
link |
that increase lipolysis, energy use from fat,
link |
and you're decreasing the lipid droplet
link |
associated lipolysis inhibitors.
link |
you're removing the break and you're pressing
link |
on the accelerator of fat loss.
link |
I think that this logically points to a case
link |
in which using time restricted feeding
link |
with a sub caloric intake seems to be,
link |
at least to my mind,
link |
the most scientifically supported way
link |
to ensure that a significant portion of the weight
link |
that one loses is from body fat stores.
link |
Any discussion about fasting would be incomplete
link |
without a discussion about what does
link |
and does not break a fast.
link |
However, there is no black and white answer
link |
And you should immediately understand why.
link |
It's because eating and not eating
link |
are not equivalent to fed and fasted.
link |
It depends on when you ate,
link |
how much you ate and where you are in your circadian cycle.
link |
We can actually arrive at a simple answer
link |
to whether or not something breaks the fast or not.
link |
Now, the technical way to go about this,
link |
would be to wear a continuous glucose monitor
link |
and to ingest little bits of food of different kinds
link |
or large amounts of food of different kinds
link |
and measure blood glucose,
link |
because ultimately blood glucose is the readout
link |
of whether or not your system is in a fed or fasted state.
link |
There are other parameters too, of course,
link |
but that's the dominant one.
link |
In so far as the scientific literature says,
link |
drinking water will not break your fast.
link |
Drinking tea will not break your fast.
link |
Drinking coffee provided it is black coffee
link |
will not break your fast.
link |
Ingesting caffeine in pill form will not break your fast.
link |
There are other things that won't break your fast.
link |
For instance, eating one peanut
link |
when deep in a fasted state will not break your fast.
link |
Eating a whole handful of peanuts
link |
might not even break your fast
link |
if you are in a very low glucose state.
link |
However, if you just finished a meal
link |
that included carbohydrates
link |
or it was a very large meal of any kind an hour ago,
link |
yes, indeed, eating one peanut could break your fast.
link |
So it's all contextual.
link |
That's what's really important to understand.
link |
Unless you're going to wear a continuous glucose monitor
link |
and unless you're going to wear a continuous glucose monitor
link |
and set an absolute numerical threshold
link |
for what it is to break your fast,
link |
I think there are some simple rules that we can follow.
link |
First of all, anything that involves sugar,
link |
in particular, simple sugars
link |
can potentially break your fast.
link |
And there's actually a study on this
link |
which shows that if people ingest even one,
link |
one gram of sugar post dinner,
link |
if they had a full meal for dinner,
link |
that can actually disrupt the expression
link |
of some of the circadian genes related to fasting
link |
and to sleep and sleep-related fasting.
link |
Now that's pretty extreme.
link |
It's almost kind of scary to think about,
link |
but that's how sensitive our system is
link |
if we already have somewhat elevated blood glucose
link |
from a meal that we ate an hour or so ago.
link |
Whereas if we have run for an hour
link |
or trained hard high-intensity training
link |
and we haven't quite reached the beginning
link |
of our so-called feeding window,
link |
will eating a small amount of food take us out of that fast?
link |
Well, depends on what the food is.
link |
If it's mostly fat, probably not.
link |
A number of people out there nowadays
link |
talk about so-called fat fasting.
link |
Fat fasting is a way to kind of wriggle past
link |
the stringency of either eating or not eating
link |
as a black and white rule for feeding window
link |
versus non-feeding window.
link |
So some people will ingest medium chain triglycerides,
link |
so-called MCTs, or people will ingest fats only
link |
until their official feeding window begins.
link |
So these are sort of how the negotiations
link |
that people carry out tend to go.
link |
But fat, of course, won't increase blood glucose
link |
and insulin as much as carbohydrates will.
link |
Protein will have sort of an intermediate effect.
link |
And as I mentioned earlier,
link |
ingesting carbohydrates with some fat
link |
will tend to blunt the rise in glucose
link |
and will extend the duration over which glucose is released.
link |
So we really can't say food X
link |
or beverage X breaks a fast.
link |
However, at the extremes, we can say that.
link |
For instance, if you drink a can of soda pop,
link |
unless you just ran an ultra marathon,
link |
you're breaking your fast, okay?
link |
Eat a piece of pizza, you're breaking your fast.
link |
If you eat purely fats, maybe, probably not.
link |
If you've been fasting for five hours or more,
link |
strictly fasting for five hours or more.
link |
So you can start to see where there's a lot of wiggle room
link |
and it's very contextual.
link |
And this is why any posts that you see
link |
or any information that you see that something does
link |
or does not break your fast that doesn't place it
link |
in the context of when the last time you ate
link |
and what you ate and your activity
link |
and your time within the circadian clock schedule
link |
of 24 hours, it's a sort of meaningless discussion.
link |
So in general, I think what's really useful
link |
if you're not going to wear a continuous glucose monitor
link |
is to try and be fairly strict
link |
about when you initiate your feeding window
link |
and when you stop your feeding window.
link |
And as time evolves and you establish a more regular routine
link |
of eating certain kinds of foods and not others
link |
that are right for you,
link |
because as I've emphasized before on this podcast
link |
and I will continue to emphasize,
link |
keto works great for some people,
link |
vegetarian keto works great for some people,
link |
carnivore diet works great for other people.
link |
Some people are omnivores, some people are carnivores,
link |
some people are vegan.
link |
All of that is great and fine by me.
link |
Everyone has to establish what's right for them.
link |
Today, we've really bypassed the discussion
link |
about foods of a particular origin or type,
link |
animal-based or plant-based,
link |
but all the same rules apply within this thing
link |
that we're call intermittent fasting
link |
or time-restricted feeding.
link |
So what breaks a fast will depend and what you want to eat
link |
or what you are willing to eat,
link |
that's a totally separate manner from when you eat.
link |
But as we've established, when you eat is vitally important.
link |
Some of you are probably wondering whether or not
link |
artificial sweeteners or non-artificial plant-based
link |
sweeteners like stevia break a fast.
link |
This will vary somewhat.
link |
And I have to say the data on this are somewhat mixed.
link |
There is evidence that when people ingest
link |
artificial sweeteners,
link |
that it can create a transient increase in blood glucose
link |
followed by a transient decrease in blood glucose
link |
This is thought to explain the increase in hunger
link |
caused by ingestion of things like aspartame and sucralose
link |
and things of that sort.
link |
There are not a lot of good studies
link |
exploring the plant-based non sugar sweeteners,
link |
things like stevia, even things like monk fruit,
link |
which is a separate category into itself.
link |
There aren't a lot of studies on this.
link |
I think most people need to establish this for themselves.
link |
The best way of course,
link |
would be to wear a continuous glucose monitor
link |
to go into a fasted state of either one hour or two hours,
link |
or maybe you've been fasting all night
link |
and then ingest stevia in whatever form you want
link |
or coffee in whatever form you want with sucralose
link |
or aspartame, et cetera,
link |
setting aside the discussion about the effects
link |
of these things on the gut microbiome,
link |
which is a different topic entirely.
link |
I think it's fair to say that in moderation,
link |
the plant-based non sugar sweeteners like stevia
link |
in particular stevia seem to have a minimal impact
link |
on overall blood glucose
link |
when considered over a fairly large time bin.
link |
Aspartame and sucralose, saccharin,
link |
I think we can say more or less the same,
link |
but as soon as you get into a discussion about those,
link |
you also have to get into a discussion
link |
about some of the evidence published in nature
link |
and other excellent journals now,
link |
pointing to the fact that when consumed in excess,
link |
not when consumed in moderation,
link |
but when consumed in excess,
link |
that those might have some detrimental effects
link |
on the gut microbiome.
link |
So do artificial sweeteners break a fast?
link |
Depends on the amount, depends on the type.
link |
And in general, I think you're probably okay,
link |
provided that you're not indulging in them too often.
link |
However, some people,
link |
just by virtue of tasting something sweet,
link |
feel a spike in their appetite that makes it harder
link |
for them to adhere to the feeding window.
link |
And so this is why you can imagine
link |
that a really well controlled study on this
link |
would be very hard to carry out.
link |
And I'm not really sure that it's worth our tax dollars
link |
to actually design and carry out a study like that,
link |
because there would be so much individual variation
link |
in terms of discipline in adhering to the feeding window,
link |
whether or not people experience increases
link |
and drops in blood glucose, how that impacts them,
link |
whether or not they're exercising,
link |
it just becomes an infinite variable space, as we say,
link |
in experimental science.
link |
So you really have to determine that for you.
link |
But I don't think that we can fairly say
link |
that artificial sweeteners break a fast.
link |
I think that would be incorrect to say.
link |
Earlier, we were talking about glucose disposal agents,
link |
both behavioral and compound based,
link |
things like metformin and berberine.
link |
And in fact, cinnamon is even a mild glucose disposal agent.
link |
It can actually reduce blood glucose.
link |
Lemon and lime juice, believe it or not,
link |
can lower blood glucose.
link |
You may have experienced this before
link |
of eating something very, very sweet
link |
and almost feeling kind of overwhelmed
link |
and kind of poisoned by how sweet it is,
link |
especially if you're not accustomed
link |
to eating a lot of sugary things.
link |
One quick remedy for that is actually a half lime
link |
or a half lemon squeezed into juice and drinking that
link |
just by virtue of the taste and by virtue of the fact
link |
that it will reduce blood glucose,
link |
you'll notice that that effect
link |
almost immediately disappears.
link |
That's the effects of acidity on blood glucose levels.
link |
So there are a number of things
link |
that can adjust blood glucose.
link |
They're not necessarily disposal agents.
link |
They're not sweeping it out of the bloodstream
link |
in the same way that berberine or metformin would,
link |
or that high intensity exercise
link |
at the appropriate times of day would.
link |
But there is one particular thing that one can ingest
link |
that can help manage psychologically and performance wise
link |
through the fasting portion of the intermittent fasting
link |
and get you to your feeding window.
link |
I've talked a little bit about this on the podcast before,
link |
but because neurons use salt, sodium and potassium
link |
and magnesium, the so-called electrolytes
link |
in order to perform their magic
link |
of chemical and electrical signaling,
link |
everything you do depends on chemical
link |
and electrical signaling and all that chemical
link |
and electrical signaling requires electrolytes
link |
in some form or another.
link |
Neurons run on the passage of ions like sodium
link |
in and out of their cell membranes,
link |
or I should say across their cell membranes to be accurate.
link |
Many people find that the kind of lightheadedness,
link |
the shakiness that's accustomed
link |
with having slightly low blood sugar can be offset
link |
by taking a half teaspoon or so of sea salt,
link |
or even just a tiny pinch of salt
link |
and putting into some water and drinking it.
link |
Some people find because of the glucose lowering effects
link |
of acidity that if they're feeling kind of shaky
link |
and not well, and they put some lemon juice into water
link |
and drink that it drops their blood glucose further.
link |
So there's a common practice nowadays
link |
that's discussed on the internet of waking up,
link |
drinking some water with some lime or lemon juice in it
link |
with a little pinch of salt.
link |
I think that little pinch of salt is a good idea.
link |
How is it offsetting all this?
link |
Well, saltwater actually has a mild effect
link |
as a glucose disposal agent,
link |
but it has a stabilizing effect on blood volume.
link |
And so because sodium brings with it water
link |
and the so-called osmolarity of your blood and your body
link |
depends on the salt levels in your blood
link |
and brain and body.
link |
Many people find that if they're feeling shaky,
link |
they're feeling lightheaded, they can't concentrate.
link |
They think they need sugar or food,
link |
but what will actually remedy that is some salt.
link |
And I know a number of people
link |
that have incorporated this practice
link |
and have written to me and saying, oh, you know,
link |
if I just take a little bit of salt and some water,
link |
they may or may not include the lemon or lime juice.
link |
They immediately feel better
link |
and find that it's actually quite straightforward
link |
to get out to that,
link |
to wait until the feeding window kicks in.
link |
This is especially true for people that are using caffeine
link |
because when you ingest caffeine,
link |
you actually excrete a lot of water,
link |
has a diuretic effect.
link |
And with that water goes salt.
link |
So it actually causes you to excrete sodium.
link |
Now, the role of sodium in blood pressure
link |
and hypertension is, you know, quite controversial.
link |
one of the premier scientific journals out there
link |
had a special issue all about salt some years ago,
link |
talking about the research around hypertension.
link |
Indeed people with chronic hypertension
link |
or high blood pressure,
link |
or very high blood pressure in particular,
link |
should be wary of ingesting too much sodium.
link |
But for most people,
link |
ingesting sodium provided they drink enough water
link |
and they don't have chronic hypertension
link |
or high blood pressure is actually beneficial.
link |
That doesn't mean you should be drinking seawater,
link |
doesn't mean you should be overindulging in salt,
link |
but many people find that they can manage
link |
their mental and physical state
link |
and even feel really terrific, real clarity of mind,
link |
and really enjoy their fast
link |
when they're ingesting sufficient salt.
link |
And all it requires really is a small pinch of salt,
link |
ideally Himalayan or sea salt,
link |
if you want to get fancy about it,
link |
but table salt would be fine.
link |
And just drinking that in some water,
link |
maybe with lemon or lime juice
link |
to offset the taste a little bit,
link |
can really stabilize one's jitters
link |
and can stabilize the mind.
link |
And you might also notice can offset that churning
link |
and yearning and appetite
link |
where you can't imagine going another five minutes
link |
before eating something,
link |
suddenly you feel okay.
link |
And that has to do with a lot of the effects of blood volume
link |
caused by ingesting salt in the appropriate amounts.
link |
In other words, sometimes you think you need food,
link |
but what you really need is salt
link |
and salt can make you feel better immediately.
link |
I'd like to mention two excellent zero cost resources.
link |
If you're going to explore time restricted feeding,
link |
or maybe if you already are doing time restricted feeding,
link |
I have no affiliation to either of these.
link |
The first is the website that I mentioned before,
link |
My Circadian Clock,
link |
which is the website hosted by Sachin Panda and colleagues.
link |
There are a lot of resources there
link |
where you can log your food intake,
link |
get information about time restricted feeding,
link |
all the science, the ongoing studies, et cetera.
link |
The other is the so-called zero app
link |
that makes it very easy to mark
link |
when you're beginning your feeding window
link |
and when you're ending your feeding window.
link |
marking when you are beginning your fast
link |
and ending your fast,
link |
or at least initiating the beginning of the unfed state,
link |
as we could more accurately call it.
link |
It's a terrific app.
link |
I've used it from time to time.
link |
I don't tend to use it in an ongoing basis
link |
because I'm just sort of used to eating
link |
at a particular time of day now.
link |
But anytime I've shifted that window,
link |
for instance, a few weeks ago,
link |
I started moving that protein intake
link |
and my entire feeding window earlier in the day.
link |
And because that takes some attention on my part,
link |
because I'm not used to doing that,
link |
I've been using the zero app and I like it quite a lot.
link |
It logs your progress and it gives you averages
link |
and you can see how many other people are fasting.
link |
Again, totally zero cost.
link |
I actually don't know who owns that app,
link |
but I think they've done an excellent job.
link |
The interface is really terrific.
link |
And as far as I know, it's available for Apple and Android,
link |
but it's at least available for Apple phones,
link |
which is the type of phone I happen to have.
link |
So check those out.
link |
My circadian clock, you just put that into Google,
link |
And the zero app, both excellent zero cost resources.
link |
In a moment, I'd like to review the parameters
link |
of a ideal feeding schedule for you
link |
and give you the variables that you can plug in
link |
to your lifestyle and your preferences.
link |
There are a couple of things that I would place
link |
into the category of frequently asked,
link |
somewhat odd, but still worthy of discussion.
link |
For instance, people have asked,
link |
will brushing your teeth with toothpaste break your fast?
link |
I think unless you're swallowing the toothpaste, no.
link |
Now, if you really want to run out
link |
and get a continuous glucose monitor and brush your teeth,
link |
then you can evaluate that.
link |
But no, people have asked,
link |
will a half glass of wine after dinner,
link |
a couple hours after dinner, break your fast?
link |
Absolutely, it absolutely will.
link |
And it's been demonstrated to do that
link |
based on the one gram of sugar,
link |
kind of eerie or scary effect that I talked about before.
link |
Scary and eerie because it just seems like one gram of sugar.
link |
How could it do that?
link |
But these are metabolic processes
link |
and they are very sensitive post meal.
link |
A few months back,
link |
I did an experiment wearing a continuous glucose monitor.
link |
And I got a surprise when I discovered
link |
that going into a sauna increases my blood glucose
link |
quite a bit, it actually spikes it as high as a meal.
link |
And then it tends to drop back down to baseline
link |
or even slightly below baseline afterwards.
link |
When I talk to people about this, somebody said,
link |
oh, it's got to be that the continuous glucose monitor
link |
was getting disrupted by the heat in the sauna.
link |
That's actually not the case.
link |
Turns out that when you go in a sauna,
link |
because you dehydrate, you're losing water.
link |
I wasn't drinking water and you're dropping a lot of water.
link |
The concentration of sugar in your blood actually goes up.
link |
And I actually put these data out
link |
in a social media post on Twitter
link |
and people were kind of shocked to see
link |
how much a sauna can spike your blood glucose.
link |
Now I do practice time restricted feeding,
link |
intermittent fasting.
link |
I'm not super strict about it.
link |
I use a kind of eight to 10 hour ish window
link |
either early in the day or late in the day.
link |
I saw this effect of the sauna.
link |
Personally, the psychological and physical health effects
link |
of the sauna are valuable enough to me
link |
that I continue to use it.
link |
I just not concerned about this increase in blood glucose
link |
to the extent that I'm going to eliminate sauna.
link |
I like to use the sauna three or four times a week
link |
So I'll use it an hour or two before sleep.
link |
And yes, indeed, it creates this big spike in blood glucose
link |
that then drops based on change
link |
in the concentration of blood sugar.
link |
I'm just not going to worry about it.
link |
Now, if you're concerned about blood glucose spikes,
link |
then you might be worried about it.
link |
But in my case, it was one of those things
link |
where it was interesting
link |
and it was worthy of discussion, I thought,
link |
because it was somewhat surprising to me,
link |
although it makes perfect sense why this would be the case.
link |
But at the end of the day, literally,
link |
it just makes sense for me to get in the sauna.
link |
Okay, so now you've heard a lot of science.
link |
You've heard a lot of examples, even a few anecdotes,
link |
and let's come up with the ideal intermittent fasting
link |
AKA time-restricted feeding schedule for you.
link |
And when I say ideal, I mean,
link |
what are the variables that are negotiable?
link |
What are the ones that are non-negotiable?
link |
What is ideal for you will depend on the context
link |
of your life and what you are willing to do consistently.
link |
So first of all, we established,
link |
based on the discussion with Sachin,
link |
who is truly the premier world expert in this area,
link |
who knows the animal and human scientific literature
link |
better than anybody, has written this incredible review
link |
and for whom I consulted,
link |
that you do not want to ingest food for at least,
link |
I want to emphasize, at least 60 minutes post waking up.
link |
Second, you want to avoid ingesting any food of any kind,
link |
even one gram of sugar.
link |
Remember, this is the ideal.
link |
One gram of sugar even would be too much.
link |
For the two to three hours prior to bedtime.
link |
He also mentioned,
link |
ideally you are spending eight hours in bed.
link |
I didn't tell you that earlier, I saved that for now,
link |
but ideally you are sleeping that entire eight hours,
link |
but simply by being in bed for that eight hours
link |
and avoiding food after waking for an hour
link |
and before bed for two to three hours,
link |
you're starting to build out the duration
link |
of this fasted period.
link |
Remember that the sleep related fasting
link |
is particularly important for the health benefits
link |
of time restricted feeding.
link |
Again, the sleep related fasting is especially important
link |
because of all the cellular repair processes
link |
that occur in the liver, in the gut, in the microbiome,
link |
in the brain, all over the body.
link |
And because of the way that that coordinates
link |
the expression of the clock genes
link |
that are then going to wick out
link |
and have many other positive effects on health,
link |
including weight and fat loss.
link |
But in addition to that, liver health, et cetera.
link |
An eight hour feeding window as a target
link |
seems to be the best target feeding window,
link |
at least by my read of the literature
link |
and in discussing it with such in.
link |
Shorter feeding windows of four to six hours
link |
tend to lead to overeating
link |
and potentially increases in weight.
link |
One meal per day type eating do not seem to do that,
link |
but those are special cases in that most people
link |
can't adhere to a one meal per day type schedule,
link |
at least not on a regular basis.
link |
And it's not very compatible with most social schedules.
link |
Although some people may be able to adhere to that
link |
in a straightforward way,
link |
but there aren't any robust studies exploring
link |
the advantages of one meal per day.
link |
So if you feel there are advantages of one meal per day
link |
for you, as opposed to an eight hour feeding window,
link |
well then by all means, use a one meal per day approach
link |
or use a four to six hour feeding window
link |
and just make sure you don't overeat in that window.
link |
Remember that most people tend to not adhere
link |
to the eight hour feeding window.
link |
They say eight hours,
link |
but they tend to eat outside of the eight hours
link |
a little bit on each side.
link |
So if your goal is a 10 hour feeding window,
link |
you might want to set it to nine hours or eight hours.
link |
If your goal is six hours,
link |
you might want to set it to seven or eight hours.
link |
And this is simply based, or I shouldn't say simply,
link |
this is based on thousands, if not tens of thousands
link |
of human subject data points
link |
that Sachin and colleagues have collected.
link |
Regular placement of the eating window
link |
or feeding window every 24 hours is important.
link |
You don't have to be absolutely rigid
link |
and neurotic about this,
link |
but you don't want it sliding around on the weekend
link |
so that it's starting two hours later
link |
and ending two hours later a couple of days a week,
link |
because then you start to offset
link |
many of the positive health effects
link |
that have been demonstrated for time restricted feeding.
link |
Remember if you eat your food
link |
within a certain feeding window,
link |
but that feeding window shifts by a couple hours,
link |
it is effectively like jet lagging your system.
link |
It is effectively like traveling a couple of time zones over
link |
eating there for a few days and coming back
link |
when in fact you're not traveling.
link |
And that's because of the way that food
link |
adjusts the circadian clock genes.
link |
Now you can offset some of that through the use of light.
link |
And I've talked extensively about how to use light
link |
in previous podcasts, but again,
link |
early morning and all day bright light exposure
link |
as safely as you can, ideally from sunlight,
link |
not through a window, et cetera,
link |
avoiding bright light in the middle of the night,
link |
extremely important for mood,
link |
offsetting metabolic dysfunction, et cetera.
link |
Not incidentally, Sachin's early work
link |
was he was one of the three co-discoverers
link |
of the cells in the eye,
link |
the so-called melanopsin cells
link |
that set the central circadian clock.
link |
So he was a pioneer in that field,
link |
which led him to be a pioneer in this field and so on.
link |
But when should that eight hour window
link |
be placed within each 24 hour cycle?
link |
Well, let's talk about ideal.
link |
Ideal, if you really want to maximize
link |
all the health benefits of time restricted feeding,
link |
you need to extend the fast around sleep on both sides.
link |
You would place it smack dab in the middle of the day.
link |
It would be a schedule in which you started eating,
link |
for instance, at 10 AM and you stopped eating at 6 PM,
link |
an absolutely dreadful schedule for anyone
link |
that wants to have some semblance of a normal life.
link |
it's not really compatible with most schedules,
link |
although some people might be able to do it.
link |
Maybe you and your family or your friends,
link |
you're eating a late breakfast
link |
and then you're having a late-ish lunch around 2 PM
link |
and then you have dinner at six.
link |
And then assuming that you go to bed around 9.30 or 10 PM,
link |
that is going to extract the maximum amount
link |
of weight related, body fat related,
link |
metabolic factor related aspects of time restricted feeding.
link |
Some people tend to fall into a category
link |
where they do best placing that feeding window
link |
later in the day and provided it doesn't run
link |
too close to your sleep.
link |
Remember you need a two or three hour buffer
link |
before your sleep, where you're not ingesting anything.
link |
That's in order to extract the benefits
link |
of time restricted feeding.
link |
Well, then starting your feeding window at 12 PM
link |
and ending at 8 PM plus or minus half an hour or so,
link |
day-to-day seems like a perfectly reasonable schedule
link |
for some people starting at 2 PM and ending at 10 PM
link |
will be that schedule.
link |
Of course, you have to take into consideration
link |
when you exercise, if you exercise.
link |
For instance, I like to exercise early in the day,
link |
if I run or if I do some moderate or light intensity
link |
exercise, regardless of what type of exercise it is,
link |
I have no trouble waiting until my feeding window kicks in
link |
around noon or even 2 PM.
link |
But if I do high intensity weight training, for instance,
link |
early in the day, or if I run sprints
link |
and I do that at 7 AM or 8 AM by 11 AM,
link |
I am very, very hungry and it's hard for me
link |
to do other things, concentrate, et cetera.
link |
Now I'm not neurotic about my feeding window.
link |
As I mentioned before,
link |
I kind of let it expand and contract a bit
link |
around the eight hour mark and feel perfectly free
link |
We're talking here in ideals, not in necessarily practicals,
link |
but other people find that they're very hungry
link |
when they wake up early in the day.
link |
If you're one of these people or you're somebody
link |
who really is trying to emphasize hypertrophy
link |
or maintenance of muscle,
link |
then it does seem that ingesting protein early in the day
link |
is beneficial, that it can be more readily converted
link |
into muscle tissue.
link |
And this has been demonstrated in at least one study.
link |
There's another study underway
link |
that's exploring this further.
link |
For people that are really, really interested
link |
in hypertrophy and building muscle,
link |
well then time restricted feeding
link |
is usually not the way they go.
link |
I mean, let's be honest.
link |
There are many people out there who are eating
link |
four or more meals per day.
link |
And they're doing that from 7 AM until 8 PM.
link |
I realized that not everybody is overweight.
link |
There is an obesity crisis indeed.
link |
The percentage of obesity
link |
and non-alcoholic fatty liver disease
link |
is just cosmic through the roof,
link |
at least in this country and in other countries as well.
link |
This country, me in the US, but other countries as well.
link |
But there are of course,
link |
people that are trying to gain weight
link |
who don't want to lose weight
link |
or who are trying to maximize physical performance
link |
or hypertrophy or things of that sort.
link |
And so of course, time restricted feeding for them
link |
might be as long as I'm awake, I'm eating.
link |
And I tip my hat to those people and just say,
link |
provided you understand what you're doing
link |
and the burden that that places
link |
on some of the other processes in your body,
link |
if that's right for you, then by all means pursue that.
link |
Another thing that we can add to this summary
link |
or key points related to time restricted feeding
link |
is the use of glucose disposal agents and or behaviors.
link |
If you find that you've eaten too close to a period of time
link |
in which you would prefer to be fasting,
link |
that's when a 30 minute brisk walk
link |
or even modest walk after eating can be beneficial.
link |
Ingesting some lemon juice or lime juice
link |
can help lower blood glucose somewhat.
link |
And then there are the things like metformin and berberine.
link |
There are even some supplements out there
link |
that combine things like berberine, cinnamon,
link |
which can lower blood glucose and things like chromium
link |
and things that have a mild effect on blood glucose,
link |
but berberine and metformin are very high potency,
link |
glucose disposal agents.
link |
And I mentioned earlier,
link |
why you would want to approach those
link |
with the appropriate level of caution
link |
and figure out the dosages for you.
link |
And for some people,
link |
the dosages will be zero milligrams is going to be ideal.
link |
And then of course we discussed how making sure
link |
that you're ingesting enough fluids
link |
in particular water and salt,
link |
especially if you're using caffeine
link |
in order to increase your levels of alertness,
link |
regardless of where that caffeine source comes from coffee,
link |
tea, or otherwise that can cause the excretion of sodium
link |
and can lead to a kind of shakiness,
link |
a lightheadedness and the feelings of hunger
link |
that may or may not be related to blood glucose.
link |
Some people genuinely need to eat.
link |
I certainly would not want to see people getting
link |
hypoglycemic to the point where it's dangerous.
link |
Certainly if you are diabetic,
link |
and in fact, for all people,
link |
you should consult with your physician
link |
when exploring any major changes to diet
link |
or additions or subtractions of anything,
link |
including supplementation.
link |
But for most people,
link |
maintaining relatively low to modest blood glucose levels
link |
is going to be pretty healthy
link |
and will allow all the positive effects
link |
of intermittent fasting to occur.
link |
And when you find that reaching that start
link |
to the feeding window is challenging,
link |
that ingesting sodium can often stabilize your system
link |
mentally and physically,
link |
and allow you to reach that window often painlessly.
link |
And then as a final point, as I mentioned earlier,
link |
provided that they are consumed in low,
link |
no or modest amounts,
link |
artificial sweeteners or plant-based non-sugar,
link |
non caloric sweeteners,
link |
don't seem to really impact blood glucose
link |
to the extent that it would quote unquote,
link |
take you out of your fast.
link |
But that like fat fasting is something
link |
that's going to be highly individual
link |
and that you're going to have to experiment with
link |
And being able to recognize when you're in a fast
link |
and when you're out of a fast at a subjective level
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and not constantly having to measure your blood glucose
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or do things of that sort can be beneficial.
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And I think if you watch for the feelings associated
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with eating and post-eating foods of different kinds
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in different amounts,
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and you watch for the feelings associated with being fasted
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for long periods of time or short periods of time
link |
of having gotten sufficient sunlight,
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of having trained hard or not trained hard
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earlier that day, et cetera,
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you can do the most important thing,
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which is to start to learn to evaluate your own system,
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to run simple, safe experiments on your system
link |
in a way that allows you to really establish
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the ideal nutrition schedule for you,
link |
whether it be time restricted feeding,
link |
AKA intermittent fasting or some other nutritional plan.
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If you're learning from and or enjoying this podcast,
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please subscribe to our YouTube channel.
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That really helps us.
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please feel free to leave us comments about this episode
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or other episodes.
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If you want to make suggestions about future episode guests
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or episode topics,
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please do that in the comment section as well.
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Please also subscribe to the podcast on Apple and Spotify
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and on Apple, you can leave us up to a five star review.
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if you're not already following Huberman Lab on Instagram,
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there I do brief posts about science
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that often are not covered on the podcast.
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So that's Huberman Lab on Instagram.
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We're also on Twitter, also at Huberman Lab.
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Recently, we launched a clips channel, Huberman Lab Clips.
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Please check out our clips channel and subscribe there
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for brief excerpts from the various Huberman Lab podcasts.
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please check out our sponsors that we mentioned
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at the beginning of this episode.
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That's a terrific way to support the podcast.
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We also have a Patreon,
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it's patreon.com slash Andrew Huberman,
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and there you can support the podcast
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at any level that you like.
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During this episode and in many other previous episodes,
link |
I discussed supplements.
link |
One issue with supplements
link |
and the supplement industry as a whole
link |
is that the quality and amounts of supplements
link |
often varies tremendously.
link |
Therefore we've partnered with Thorne, T-H-O-R-N-E,
link |
because Thorne has the absolute highest levels of stringency
link |
with respect to the quality of ingredients
link |
and the amount of the ingredients
link |
matching what's on the label.
link |
If you want to see what I take
link |
and get 20% off any of Thorne's supplements,
link |
you can go to thorne.com slash the letter U slash Huberman.
link |
You'll see the list of supplements that I take.
link |
You can get 20% off those.
link |
And if you enter the Thorne site through that portal,
link |
you get 20% off anything that Thorne makes.
link |
I know we covered a lot of information today.
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I hope you learned a lot about time-restricted feeding.
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I hope you learned a lot about metabolism
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and energy and health
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and how when you eat is as important as what you eat.
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And last, but certainly not least,
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thank you for your interest in science.
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And I'll see you in the next one.