Effects of Fasting & Time-Restricted Eating on Fat Loss & Health

This section of the episode develops the topic through the following source points: Welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today we're talking all about fasting, and anytime we're talking about fasting, we are also talking about eating because we all need to eat sooner or later. We're going to talk about how fasting and when we eat influences a large range of aspects of our health and wellbeing, both physical and mental. So, well nowadays, most people are familiar with the term intermittent fasting, also sometimes called time-restricted feeding. I think most people don't really understand how that process works. It's sort of obvious that intermittent fasting, aka time-restricted feeding, involves eating at certain periods of each 24-hour cycle or maybe even not eating for entire days in some cases. But if you think about it, everybody sleeps eventually, and therefore because people don't eat during their sleep, almost everybody is employing some form of intermittent fasting or time-restricted feeding. What we're going to talk about today is how particular schedules of time-restricted feeding can impact our health in different ways. And when I say different ways, I mean we are going to talk about how intermittent fasting, aka time-restricted feeding, impacts weight loss, fat loss in particular, muscle maintenance and loss and gain, organ health such as gut health and liver health, the genome, the epigenome, inflammation, sickness, recovery and healing from sickness, exercise, cognition, mood, and lifespan. So we're going to cover a tremendous amount of information. I promise to make it all directly accessible, regardless of whether or not you have a background in biology and metabolic science or not. I'm also going to talk about a lot of tools. In fact, I'm going to discuss a number of tools during today's episode that actually make it such that you don't have to follow any feeding schedule or fasting schedule, same thing if you think about it, in any absolutely strict, regimented way. Meaning if you were to only eat during an eight-hour period of each day most of the time, but then occasionally eat across a 12-hour period of the day, in theory, that could actually have pretty serious detrimental health effects, and yet there are things that you can do to attenuate those negative effects. In fact, there are things that you can do and or take that can make it as if you did not eat at all. And so we'll discuss what those tools are. And in many cases, for sake of health, weight loss and performance, making the body think that it did not eat at all can actually be quite beneficial. Today we're going to cover mechanism and we're going to cover tools. Before we do that, I want to highlight a particular result that was published recently because it serves as a useful backbone as we wade into the conversation about fasting. This is a study that was published in the journal, "Cell Metabolism," a Cell Press Journal, excellent journal, and the title of the paper is Fasting Blood Glucose as a Predictor of Mortality: Lost in Translation. And I'll explain what the lost in translation part means in a moment. But the basic takeaway of this study, and I should mention that the first author of this study is Palliyaguru, P A L L I Y A G U R U, guru. Palliyaguru et al. The basic finding of the study is that in humans, higher blood glucose is associated with mortality. And in fact, if you look at blood glucose, resting blood glucose across the lifespan, what you find is as people age, resting blood glucose goes up. Now this is very interesting because for a long time it was thought that metabolism actually goes down as we age, and to some extent that's true, but the reductions in metabolism are not nearly as robust as we once thought that they were across the lifespan. However, unless there's something done to mitigate the increase in blood glucose associated with the aging, almost everybody experiences a gradual but regular increase in resting blood glucose that predicts mortality. Now, the title, as I mentioned, is "Fasting Blood Glucose as a Predictor of Mortality: Lost in Translation." And the reason that they included "lost in translation" in the title is that, what I just told you, that increases in resting blood glucose predict mortality, or are correlated with mortality, is true for human beings and for nonhuman primates, monkeys. But the opposite is true in mice. And so I thought it was important to use this study as an example of where studies in mice often, but not always, translate to humans and to nonhuman primates.