Why You Get Hungry & What To Do About It: How To Defy Overeating, Conquer The Buffet, Stop Cravings In Their Tracks & Much More!

Yo, yo, yo. Stefan. My guest on today's podcast has a very interesting last name. Some people think it's Guayonet, some guy, some Guayane. Either way, I don't care because he's a smart cookie. He's got. He's got super duper high smarts in the smarts category, specifically when it comes to nutrition. And he has one of the best books I think I read in 2017 on nutrition specifically. It's called the Hungry Brain. It's basically about hunger and overeating, but it's. It's not like insulting your intelligence by telling you about how if you sleep, you're more likely to grab a Snickers bar. I mean, if you don't sleep, you're more likely to grab a Snickers bar. No, instead, he delves deep into things like mice and rodent research and. Dude, you got to read the book. You gotta listen to the interview and you gotta read the book. My apologies if he's like super duper, duper scientific. I'll try and keep him reeled in during this episode, but either way, you need to own the book, even if it takes you a year to read because it's so scientific. Read it. Why you get hungry and what to do about it. In this episode of the Ben Greenfield Fitness Show.

We know that animals and humans that are obese, that have obesity require a higher level of leptin to stop that starvation response. And so they literally have a higher set point. It's like turning up the heat on your thermostat. It is true that a lot of our processed food comes from corn and soybeans, and we eat a lot of processed food, but you find the same thing in non industrial cultures where most of their calories are coming from just a few staple foods.

He's an expert in human performance and nutrition, voted America's top personal trainer and one of the globe's most influential people in health and fitness. His show provides you with everything you need to optimize physical and mental performance. He is Ben Greenfield.

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Hey, folks, it's Ben Greenfield. And I gotta tell you, most of us try to eat well. We try to avoid weight gain, but a lot of times our actual behavior, our actual cravings don't live up to those lofty intentions. And a neuroscience obesity researcher and today's podcast guest, Stephane Guyne, argues that we're actually betrayed by our own brains, by our own ancestry that drives us to crave and to overeat food. And he just wrote this fantastic book called the Hungry Outsmarting the Instincts that Make Us Overeat. Frankly, it is. And maybe it's just because I'm a complete nerd. One of the best scientific treatises of why we eat the way that we do, why we get hungry, and why certain things really spark our appetites, and why, even when we're following a diet, we still find ourselves digging for chocolate ice cream or Ben and Jerry's Chunky Monkey at midnight. So we're going to delve into all that today. And it really is stuff that goes way above and beyond the current, I guess, the current popular theories of obesity and appetite and overeating in this book. It really is pretty groundbreaking. Will take everything that Stephan and I talk about and put it over@BenGreenfieldFitness.com HungryBrain if you want to check out his book or anything else that we discuss. BenGreenfieldFitness.com HungryBrain and by the way, if you don't know who Stefan is, a, he's a smart cookie. B, he's an obesity researcher. He's a health writer. He has a PhD in neurobiology at the University of Washington. He runs a blog called wholehealthsource.org and he lectures all over the frigging planet on things like obesity and metabolism and diet. So this dude knows his stuff. Stephan, welcome to the show, man.

Thanks. Good to be here, Ben. Yeah.

Yeah. This book, like, I. When I. When I sat down and read it, I had so many pages folded over, I wasn't really quite sure where to start. But I guess the main. The main thing for me is, you know, you launch into the book about why what you present in it is absent from popular theories of obesity. Meaning, like, there's all these theories out there about why people get obese. But you say a lot of what you present in the book isn't in those theories. And I was wondering if you could kind of explain why that is, why you even had to write this book.

Yeah, yeah, absolutely. I think that's a good way to introduce this. And, you know, I want to preface this by saying that I'm not saying that these theories of obesity are necessarily wrong or are not useful, but I think they're all missing something, and I'll explain what that is. So there Are there's the theory of calories in, calories out, that basically your body fatness is determined mostly by voluntary behaviors and willpower. So you should just track your calories, and that's going to be your most effective way to manage your body composition. There's the idea that carbohydrate is the primary determinant of body fatness via its impact on insulin. There's the idea that physical activity is a major determinant. There's emotional eating, there's food addiction. These are all, you know, leading popular concepts of the causes of obesity. And I think that a lot of them do actually have some value. But I think that if we really want to understand why we overeat and why we carry excess fat, and if we really want to understand what ties all these things together, we have to look at the brain. Because the brain is. Is the thing that determines all of our behavior, including our eating behavior, as well as everything else. It determines our feelings, such as our cravings, determines our hunger level, and it determines a lot about our physiology. That determines how our body uses the.

Food that we eat versus, say, like our pancreas or our insulin or the incretin hormones formed in our gut, et cetera. You're saying it all starts in the brain?

Yeah, and I'm not saying that there's nothing outside of the brain that matters. What I'm saying is that the brain is kind of the central regulator of a lot of this physiology. And certainly it's the only regulator of our behavior, or it's the only thing that generates our behavior, I should say. And so I think that. And there are reasons why understanding the brain doesn't really tend to enter in popular theories of obesity. It's because the brain is complicated and because until recently, we didn't really have enough information in the research world to come to useful conclusions about the role of the brain in a lot of this stuff. And so it's only recently, with the real explosion of neuroscience research and techniques for doing that research more and more effectively, only in the last couple decades, really have we gained some really very profound insights into how the brain generates all these things that we care about related to food intake and body fatness. And I think that when we take that brain centric perspective, that really helps to kind of. I think that's the most useful perspective because we're really focusing on the thing that is actually central to all these things that we care about, instead of kind of peripheral things that are outputs of the thing that we really care about.

Right.

And so I think that there's a lot of this information in the scientific community that's really, I think, is very, very profound and helps us understand at a very deep level what's going on. But a lot of it hasn't really trickled down into a general audience context because it's complicated. And so my goal with the book was to take all this complicated stuff and kind of like streamline it and package it in a way that a sophisticated general audience could understand.

Yeah. And you talk about a lot of that research in the book from From Mice to Rats and Beyond. There's just some frickin fascinating stuff that I want to get into regarding this, this new research that you hinted at. But first tell me about the story of the fattest man on the island and why you included that in the book, because I thought that was great.

Yeah. So one of the things that I'm really interested in is the question of what is biologically normal for humans. And because, you know, we can look at statistics for the United States and we could say what statistics? What's statistically normal for the modern United States, but that doesn't really tell us what's biologically normal. That doesn't really tell us what the human body evolved, how the human body evolved to function. So I think that's a really important question to answer. And to answer that you have to start looking at non industrial cultures. You have to start looking at archeology, hunter gatherer, non industrial agriculturalists. And you have to see like, what is their level of body fatness, what is their health, are they getting diabetes, are they getting cardiovascular disease? And how are they living, what is their diet, what is their lifestyle? And can we get any clues from that about the connection between diet and lifestyle and obesity and health outcomes? And so I start to kind of start to get at some of these questions. I use a story that I think is a pretty striking illustration of this principle, which is Stefan Lindenberg, his research in the early 1990s, I believe. Stefan was a researcher at the University of Lund who was fascinated by evolutionary health.

The University of Lund, where is that?

Sweden.

Okay, gotcha.

Yeah. And he was fascinated by this idea of evolutionary health. And he wanted to do research to see, you know, how much credibility this idea had. So he went to this very isolated island in the Pacific. It's part of, considered part of Melanesia. And the island is called Catawba. And it's, it's one of the Trobriand Islands. And people living there are scarcely touched by industrialization, at least they were at the time of his study. And they're horticulturalists, which means they grow primarily tubers and plantains and things like that. And they had a very simple, starchy diet that it was mostly starches that they cultivated, plus coconuts and fish and some vegetables. And what he found was on that island, there was one person who really stuck out. There was basically no obesity, and there were almost no people who were even slightly overweight on the entire island. We're talking about thousands of people. I mean, this is like, totally unimaginable in any industrialized society. Right?

Like the complete opposite of the cruise ship on the cartoon wall.

Yeah, yeah, that's right. It was not. Didn't look like people on a cruise ship.

And.

And I mean, you look at these people, they're not starving. And in fact, he talks about in his paper how they had excess food. Like they would often discard food because they had too much of it. And not to say that their food supply didn't fluctuate, but there was no recorded famine on the island in recent history. And you look at these people, and they're lean, they're well muscled, they really don't look like people who aren't getting enough to eat, but yet there's very little obesity. Except for this one guy that he found, this guy who in my book I call Utala. And I'm just going to read a little bit. I'm going to read this passage. As it turns out, Utala wasn't living on Catawba at the time of Lindenberg's study. He was only visiting. He had left the island 15 years earlier to become a businessman in Alatau, a small city on the eastern tip of Papua New Guinea. When Lindenberg examined him, utala was nearly 50 pounds heavier than the average Kitavan man of his height, and 12 pounds heavier than average than the next heaviest man. He was also extraordinary in another respect. He had the highest blood pressure of any Kitavan examined by Lindbergh. Living in a modern environment had caused Utala to develop a modern body. So he was born on Kitava, he grew up on Kitava just like everybody else. But then he went to Papua New guinea and began living a more industrialized lifestyle as a businessman.

Right.

And so he had this same genetics as everybody else. The same, you know, all the in utero, all the prenatal epigenetics, all the childhood nutrition was all the same. But as an adult, he was exposed to this industrial diet and lifestyle, and it made him Overweight. He was basically just under being obese on the body mass index scale, just just below being obese. He had a lot of abdominal adiposity. And so I think, to me, that's a really striking example. And you see this all over the world. This is like an anecdote that illustrates my point kind of in a colorful way. But I mean, you can look at data that are not anecdotes, and it shows the same thing that it's not just genetics. When you take people who are living a traditional lifestyle and eating a traditional diet, and they shift onto an industrial diet and lifestyle that more closely resembles, you know, affluent countries like the modern United States, you see dramatic increases in body fatness as well as diabetes and coronary heart disease and other things that are associated with that.

Yeah, there's actually a really good book about this that goes into all sorts of different populations, from like, you know, Hispanics to African Americans. It's called the Jungle Effect. And it is written by this physician who heals her patients by returning them to the diet that would have been more matched to their ancestry. It's a fascinating book, but, you know, it kind of highlights this concept that once you. Once you take someone out of their natural ancestral eating protocol and put them into a typical western diet, you tend to see obesity. But at the same time, dude, this doesn't seem to be like a huge surprise, right? Like, this doesn't really. Doesn't really seem to be like a groundbreaking explanation of obesity as much as pointing out the fact that, yeah, when we don't eat our ants ancestral diet, we could tend to get fat. So when it comes to that, I think that delving into the brain is something that gets a little bit more intriguing. And in that sense, you start to talk in the book about what type of foods we actually get attracted to and why these western diets get so they have such a high propensity to make us eat more. And you start that by talking about why kids like things like ice cream and Brussels sprouts, and especially with regards to this part of the brain called the ventral striatum, why that is. Can you delve into why we actually crave things like ice cream versus Brussels sprouts?

Yeah, absolutely. And I want to first give a little bit of a more zoomed out perspective and just say that there are certain properties of food that we're attracted to, but there's a bigger picture where the brain also factors in things like convenience when it's determining your. When it's. When it's engaging in its decision making process around eating. But obviously the physical properties, the physical and chemical properties of food are very, very important to our motivational level with regard to food. And this makes a lot of sense because certain physical and chemical properties would have been a lot more valuable to our ancestors than others in terms of their survival and reproductive success. Reproductive success is the currency of natural selection. And so things that increase reproductive success are going to be selected for over evolutionary time. And so basically people who, you know, genes that make you better at seeking the things that make you survive and have a bunch of babies in a, you know, and I'm talking about our distant ancestors here are things that are going to get passed down and reinforced. And so this really gets at the heart of the issue of what is it exactly about food that we want? What is it exactly about food that motivates us, that makes us go after it? I think this is a really fundamental question that I haven't seen answered in any other kind of general audience book. And but this is something that we know quite a bit a lot about in science. And basically how it turns out is that the brain is hardwired. And this is the brain, I'm talking about all humans. So these are things that are common to all cultures. No matter where in the world you grow up, you're going to be interested in these particular food properties. The brain is hardwired to seek certain properties in food. And these include sugar, fat, starch, salt, protein, and the amino acid glutamate, which is that umami meaty flavor that you get in bone broth and cooked meat and soy sauce and msg.

Right. Protein is in there, really?

Yeah, yeah, proteins, I think it is. And so the reinforcing effect of protein has not been directly demonstrated in humans, but it has been demonstrated in rodents.

Okay.

And I think it's likely that it is in humans too. And, and data and hunter gatherers support that as well because they, they definitely are motivated by protein somewhat independently of total calories. That's actually the, the second seems to be the second biggest motivator for them when they're choosing their food resources. Number one is calories, number two is protein. So I think there is some, some wiring there around protein.

The only reason I question that is because in the absence of things like the, like the umami flavor and the fats and the salts and the sugar, sometimes protein can seem a little bit bland.

Yeah, I agree with that. I agree with that. However, I think once you start to combine protein with salt, like salted meats, you get a food that actually is associated with craving in a pretty high percentage of people, especially men. So I don't know that, like, you know, a lot of the proteins that we eat are actually pretty natural. Like, meat is a pretty natural food, pretty ancestral food. So I don't know if meat really can kind of rise to the level of, you know, quote unquote addictiveness that you're gonna see with things like brownies and cakes and, you know, that sort of thing. But I think it definitely has a motivational value for us. And especially meat does. I think that's very hardwired. So, anyway, so our brains are literally wired to look for these specific properties in food, and those are food properties that actually spike dopamine in a part of our brain called the ventral striatum. And the ventral striatum is really important. It's a key part of the brain for motivation, learning to be motivated over time as well as pleasure. And this is also. This area is also known as the nucleus accumbens. And basically, when dopamine spikes in your nucleus accumbens, that makes you motivated to go after whatever it was that made the dopamine spike. And so if you eat a food and there's tons of fat and sugar in it, for example, your dopamine is gonna start to spike. And that tells your brain, wow, this thing that you just ate is awesome. It's a really great source of fat and sugar. And so what your brain's gonna do as a result of that dopamine is it's gonna collect all the sensory information that was associated with that food you just ate. So it's gonna say, let's say it was a brownie. It's gonna say it's gonna remember the smell of the brownie, it's gonna remember the appearance of the brownie, it's going to remember where you got that brownie, it's going to remember who you were with, it's going to remember the name of maybe the restaurant where you had it. And all those things are registered in your brain. And because of that dopamine, those things become motivational cues because of their association with that dopamine that was triggered by that sugar and fat. Those things become motivational cues in the future. So the next time you smell that brownie smell coming out of the oven, it's going to start spiking your dopamine again, and you're going to feel a craving, you're going to feel an instinctive motivational drive to eat that Food which we call cravings, and then it may be difficult for you to stop yourself from eating it at that point. So basically, we learn to enjoy. So there are innate preferences. There are these basic food properties that we're hardwired to enjoy, and then there are learned food preferences about the flavors and aromas and textures of the foods that we repeatedly associate with those innately preferred preferences. And so everybody in the world loves fat and sugar, but not everybody loves the flavor and aroma of traditional, you know, Szechuan cooking in China. And not every Chinese person is going to like the smell and taste of stinky French cheese. Those are things that we acquire over our lives by virtue of their association with those reinforcing properties. And so for a kid, you know, if you think about, especially for children who haven't had a lot of time to form these preferences. So like for example, if you're, if you, some people as adults like kale, the reason we like kale is because we had it with fat and salt so many times that our brain has made that association. But if we never put fat and salt on it, we would never develop that preference and it would just taste like bitter crap. Because the brain doesn't care about vitamins and minerals. Those are not motivational, those are not hardwired motivational properties. You can't reinforce behavior by adding vitamins and minerals to food. You can't taste vitamins and minerals. The only exception is sodium chloride. That's the only essential nutrient, essential micronutrient, that we can actually taste, that we can actually perceive. And so basically the reason kids like ice cream is that it has everything that the brain is hardwired to enjoy. It's very calorie dense, it has lots of fat, it has lots of sugar, it doesn't have any bitterness, right?

Andand that's what causes the dopamine release in the ventral striatum. That' sthat's what actually makes a food addictive, is its ability to cause that ventral striatum release.

Yeah, absolutely. And when you have these properties that are combined, especially, you know, the fat and the sugar together in a really concentrated form, you get a lot of dopamine release. And so it's pleasurable on the spot. But all that dopamine also reinforces your behavior so that in the future it's going to be even harder for you to refuse that food. Your behavior is going to be getting pushed on a non conscious or minimally conscious, impulsive, instinctive level, that craving, your behavior is going to be getting pushed in the direction of that ice cream. But a kid has very little motivational drive for vegetables. I mean, kale, brussels sprouts, broccoli, these things are notoriously unpopular with kids because they don't contain those innately preferred properties that the brain's looking for that drive dopamine, that drive pleasure and reinforcement and motivation and cravings.

Right. So I mean, one example that you use in the book is, for example, chocolate, because that has a ton of these things that cause that dopamine release in it. Right. It's got calorie density and fat and carbs and sweetness. And then you even mentioned how it has like theobromine, which is a mild stimulant like caffeine. And it's why so many people get coffee, or not coffee cravings, but rather chocolate cravings, because it is a perfect example of one of these foods that causes the dopamine release. And one of the things that you talk about as well is the idea of sensory specific satiety, meaning that this is also related to how many different, the way I understand it, I think the way you explain it is how many different sensory properties a food has and you actually tie that into how we can do a better job not overeating at the buffet. Can you get into, into, into a, the little trick for the buffet and what kind of science that's based on.

Yeah, yeah, absolutely. So slight clarification. It's the number of sensory properties that a meal has rather than a specific food. And so.

Okay, got it, yeah.

So basically the way sensory satiety works, and this relates to a very basic property of the nervous system called habituation. So essentially when you're first exposed to some stimulus, like let's say you're driving to work and you see a new billboard that they just put up last night, you see it for the first time, might catch your eye. Maybe it's kind of interesting, maybe it's got, you know, good looking member of the opposite sex on it and it catches your eye.

Or a bar of chocolate, or a.

Bar of chocolate and it catches your eye. But I mean, the next time you see it, if you were, if you were shown that 25 times in a row, you're going to pay less and less attention to it. That billboard is conveying less and less information value to you each time you see it. And so that's a property called habituation, where when you're repeatedly exposed to the same stimulus, you're going to respond to it less and less. And this is something that you see all the way down to jellyfish, which are very, very distant cousins of ours. You can poke a jellyfish and it'll react. And then if you keep poking it in the same way over and over again, each time you poke it, it will react less and less and less. It basically gets habituated to that stimulus. This is something, this is a very fundamental property of the nervous system that's very useful that we see all the way up to humans. And so the way that works when we sit down to a meal is that we actually become habituated or satiated by certain specific food properties, certain sensory properties. And so, for example, if you're sitting down at the table and eating something with a salty, proteiny flavor profile, you can eat until you're completely full on that steak. But that doesn't mean you're going to be full and not want to eat a potato. And eating that potato doesn't mean you're going to be full and not want to eat a piece of dessert afterwards, something that's sweet. So this is why we overeat at buffets, basically, because buffets have an almost unlimited amount of sensory variety. So you can have, you can eat your full on one item, but if there's 10 different items on your plate that you have to eat your fill of, you're going to end up eating a lot more total calories. And this has been demonstrated in randomized controlled trials a number of times. Basically, the greater the number of unique foods, unique in terms of their sensory properties that we have at a meal, the more total calories we're going to eat. And we don't even feel more full. We don't even feel more full, but we do it anyway. Just because fullness isn't just about the number of calories you ate, isn't just about the volume that you ate. It's also about how your brain is perceiving your intake of specific sensory property foods.

Got it. So the idea then would be, if I were at Whole Foods and I didn't want to overeat at a place like Whole Foods, what I would do is try to just choose like two or three items to reduce variety. Because once you introduce variety, you decrease satiety, meaning that I could eat a thousand calories of say like two to three different foods like the sweet potatoes, the broccoli and the roast chicken. Whereas I could eat 2,500 calories of like seven different foods. The satiety effect would be similar, but by having a wider variety of foods, it would take a longer time for me to feel full.

Yeah, that's exactly right. Yeah. So, and I mean that, that's kind of the strategy that you can adopt when you go to a buffet. You just select a few things that you want to eat that you think will make a healthy and satisfying meal and you stick to them.

And that's what I do, by the way. I walk the entire buffet, or from a whole foods, I walk everything. Rather than just like starting and just begin. Because what happens is you'll put one thing on, it looks pretty good, and then you'll see something that looks even better and put that on. And by the time you're done, you've got like eight different things when you could have done a quick walkthrough, chosen like your three top items and just gone from there. And it does work. Like when you just put a few things on, you eat far less and you beat that buffet effect that you describe in the book. Now you also go into something I found fascinating, what non industrial diets have in common. And it's related to this limited variety of foods. Can you go into what it is that non industrial diets have in common and why that's helpful here when understanding why we overeat?

Yeah, absolutely. So there are three properties of non industrial diets that I highlight in the book that I think are important differences between non industrial and industrial diets that are very relevant to food intake, behavior and especially calorie intake. And the first one is that non industrial cultures tend to have a limited variety of foods. And this actually, I think comes as a surprise to a lot of people because it's kind of counter to the prevailing narrative that everything we eat is made out of corn and soy. And if you look at hunter gatherers, they ate 100 to 200 different types of food around the year. But I think if we take a closer look, that argument kind of falls apart. And this is something that I became aware of when I started studying non industrial cultures. And I'll use as an example the Kung San of the Kalahari Desert. So these are very well characterized hunter gatherer culture. I'm actually not sure that they're really hunter gatherers anymore, but at the time they were Characterized, they recognized 105 plants as edible. And so they would eat a high proportion of those in a typical year. So that's a lot of different types of food. But only 14 of those actually formed the bulk of their food intake. And of those, actually half of their year round calorie intake came from one food, the Mongongo. Fruit and mongongo nut. It's a fruit with a nut inside. And so actually their diet really, and especially on a daily basis, on any particular day, they weren't eating a great variety of foods. They would just have a few different things. There would be meat, maybe there would be some mongongo nuts, maybe there would be some fruit. But they weren't eating a hundred different things every day. You know, in, in each meal there were only a couple different things. It's whatever you could find. You weren't going to go out. It's inefficient to go out looking for a million different things. And they would share. So there was some variety, but they weren't eating a hundred things every day or even every week. They're eating mostly just a few things. And this is what you see in almost every non industrial culture. Basically they narrow in on the most efficient way to feed themselves, which tends to be one or a few key food resources and then they focus on those. So like if you look at Polynesian Islanders, they ate a lot of taro, they ate a lot of yams, they ate breadfruit, they coconuts, and then that was the bulk of most of their diet. And then if you look at, you know, agricultural populations, usually they, most of their diet comes from one or two grains like corn or sorghum or rice, or in some other areas maybe there was cassava or potatoes and then they would supplement that with things like beans and meat and seafood and game. But most of their diet was coming from one or two foods. So what you see is really, if you really look at the day to day eating behavior of non industrial cultures, the variety in their diet is actually rather limited. And then the second point I'll make is that if you think that our diet today is limited in terms of its variety, I encourage you to walk through the produce section of a grocery store and count the number of different species you can find in the produce section that's available year round in a grocery store. I mean, there's a very large variety, especially now that we can get anything at any season. There's a very large variety of different foods. And that's just the produce. I mean, it is true that a lot of our processed food comes from corn and soybeans and we eat a lot of processed food. But you find the same thing in non industrial cultures where most of their calories are coming from just a few staple foods. So I think that actually especially if you're considering the sensory variety, because I mean, even from the Basis of corn and soybeans. Industrial Our industrial food system has been able to produce an incredible variety of sensory experiences. And so even though they might be made of the same ingredients, you have all these different flavor profiles that are coming out of it. So from on a sensory level especially, there's actually quite a bit of variety in ourin our diet.

Yeah. Andand that's one of the really interesting things that I've noticed among a lot of successpeople who are really successful, like maintaining lean body mass or not. Overeating is similar to me not trying to toot my own horn, but I eat the same thing for breakfast almost every morning, same thing for lunch almost every day. Now that's not to say that there's not some amount of dietary variety. In the winter, my lunch is more like cooked vegetables with some fats and oils, and in the summer it's more raw, cold vegetables. So I am into the seasonal eating thing, but it's one of those deals where I just limit the variety. And when I do that, when I don't have 12 different things that I'm piling onto a plate, I'm able to eat far less. And it looks like when you look at a lot of these non industrial diets that you describe, they indeed not only have that limited amount of variety, but it looks like based on what you say, they're not adding a lot of refined starch and sugar and salt and concentrated fat to the meal, so they're not making them extremely palatable. And then they use few cooking methods. That was the other thing that you went into was, you know, they're using like two or three different cooking methods rather than, you know, thinking they have to outfit their kitchen with fricking like a, you know, a sous vide and a steel cooking pan and a blender and a dehydrator and a gas stove and, you know, all these different cooking methods. And so takeaway message for me was that, hey, if you're having difficulty overeating, have simplicity, don't buy every kitchen tool on the face of the planet. Buy a limited variety of foods, don't have a ton of like salt and spices on hand, and, and simply eat in almost like a little bit of a bland way. And you know, based on, on the research, from what you're saying, you know, and this ventral striatum, that could be a very, very good way to keep yourself from overeating, correct?

Yeah, yeah, I think so. And I mean, yeah, I think simplicity is really the key. Like our ancestors ate in a Very simple way. They prepared food in a simple way and they didn't have a lot of ways to embellish it. And I think that that is an important but often overlooked aspect of ancestral eating. And I wanted to expand a little bit on this thing that you brought up. So basically these three properties, you said the other two, which is that they have a limited ability to concentrate the reinforcing properties of food. So those things that the brain is innately in tune with, and third, that they use fewer cooking methods, I think this limited ability to concentrate the reinforcing properties of food is really important. So, like, I like to use cocaine as an analogy, and I think drugs are actually a pretty good analogy here because they literally, you know, drugs of abuse literally act through the same pathways that food does when it drives our motivation and when it makes us crave. Those are pathways that evolved to get us to seek good things like food and sex and everything else that are kind of hijacked by drugs. But I think drugs make a really clear analogy that helps us think about this. So for cocaine, you know, that comes from the coca plant, which is indigenous to South America, and it's been used for thousands of years as a mild stimulant. It's mild stimulant, appetite suppressant. People just chew these whole leaves. They just chew the leaves and that provides them with this kind of like caffeine, like stimulant, which is very low doses of cocaine is what it is. And that. And that has beneficial effects, just like caffeine has beneficial effects for us to stay awake and be productive and whatever. But then if you take that property of the coca plant, if you take the active ingredient, quote, unquote active ingredient that spikes dopamine and you purify it, you get cocaine and cocaine, it's the same thing, it's just more pure. And by technology we've been able to isolate that active ingredient. That's what our brain is looking for. And then it spikes dopamine way more. And then we've been able to further tweak it by free basing it, which turns it into crack, which crosses blood brain barrier and the mucosal barrier much faster, gives you a faster hit and is even more reinforcing, gives you a faster, higher dopamine spike. And then it turns it in, it turns this natural substance that is mildly reinforcing and useful into what ends up becoming a life destroying drug or can be a life destroying drug. And so I think the analogy extends to food where basically, if you look at A whole piece of whole fresh fruit that's got sugar in it. That's something that spikes dopamine. That's something that your brain wants. Sugar tastes. I mean, fruit tastes good, right? But it's not something you're gonna like, gorge on and become obese because you ate too much fruit. It tastes good, but it's not like, insanely good. And, you know, compared to, like ice cream or a brownie or whatever, most people would choose that over fruit, right? Just on the basis of pure visceral pleasure, not in terms of thinking about the health impacts. But what happens when we take that? I mean, what happens when we take the active ingredient of that fruit, the sugar, the thing that spikes your dopamine, the thing your brain's looking for in that fruit? What happens when we take that and we concentrate it, we concentrate it into pure sucrose? We have taken something that is a useful, constructive substance that spikes dopamine to a degree that we would have seen in our distant ancestors and turned it into this highly dopamine spiking, concentrated substance that we can add to food that basically spikes its dopamine potential as well as its motivating potential beyond anything that our ancestors would have experienced. And this is, not surprisingly, why these types of foods lead to addiction, like behavior in a lot of people. And the concept of food addiction remains controversial. But, I mean, I think there's no doubt that certain types of foods, and they're all foods that are very concentrated in these properties I was talking about earlier. These things the brain is hardwired to be motivated by and to experience dopamine spikes from. Those are the foods that people experience addiction like motivational levels and addiction like behaviors around. And I think it's because basically our brains didn't evolve to handle the massive dopamine spikes that happen when you isolate and purify those active ingredients and just like blast your brain with them. And it's very analogous to cocaine hunter gatherer populations. Our ancestors simply didn't have the technology to purify and refine the active ingredients in food, like sugar and salt and glutamate, the things that really spike our dopamine. They didn't have the technology to concentrate those things and mix them together in the ways that we can today. So basically, technology, as technology and affluence have progressed, we've gotten better and better at catering to the instinctive preferences of our own brains. And we're so good at doing that now that we are creating destructive behaviors in ourselves and destructive levels of Food motivation.

Now, one of the things that struck me as potentially paradoxical was you go into the fact that despite having a large amount of simplicity and few cooking tools and not a lot of salt and sugar and fat added to the diet, the idea of moderation in eating is actually something foreign to hunter gatherers. And we see them eating well, we see them engaging in downright gluttonous habits. Can you go into why that is? Like how our hunter gatherer neighbors can be gluttonous and yet not obese?

Yeah, absolutely. So I think this is, this kind of takes us to a different angle that we can use to address the question what is it fundamentally that the brain is motivated by about food? And we can look at this from a broader perspective now and say, not, excuse me, it's not just about the food properties, but it's about how we acquire those foods in the environment, how much effort and how much time are required for us to obtain those foods. How does that affect our motivational level and how does that affect the big picture of our decisions to eat and our motivation to eat? And researchers have modeled this really remarkably in a variety of species using a discipline called optimal foraging theory. And first they showed in, they showed this first in non human animals that basically you can predict an animal's foraging behavior, an omnivorous animal that has a lot of potential things that could eat. You can predict what it's actually going to go after based on a very simple equation. It's called the optimal foraging equation. And this is that the value of a food item to that organism is equal to the number of calories it contains, minus the number of calories it takes to obtain and prepare it divided by time. So it's the calorie return rate of that food. And this is very similar to, you know, basic economics equation for prop. Profit maximization. It's just a basic return rate calculation. And what you see is that animals behave according to that equation. And one of the animals that behaves according to that equation is human hunter gatherers. And so you can actually to a pretty remarkable degree predict their foraging decisions based on this equation. And so what this equation predicts, it predicts some pretty interesting things. And one of them is that if a food contains a lot of calories and it doesn't require a lot of calories to obtain, and it doesn't require a lot of time to obtain. So if the calorie return rate is very, very high, that food is going to have a very high predicted value to that hunter gatherer. And so it's going to create a very high motivational state and that hunter gatherer will potentially gorge on that food resource. So basically, it's easy calories. It's opportunism. When you have the opportunity to get easy calories, you're going to take advantage of it. That would be a more colloquial way of putting that, what the equation implies, and that's exactly what we see. So the anthropologists that I spoke to, most of them were describing these insanely gluttonous incidents that they observed among hunter gatherers when they had these sort of like, easy calorie windfalls. So people chugging a quart of honey. Like, imagine that, chugging a quart of straight honey.

Yeah. Seriously, that. That's like almost gag reflex. I mean, there's honey up in our pantry right now. But what you're saying is that they would, like, give up a hunt for an animal to, like, like, wander off to the side of the path and just, like, eat copious amounts of honey without ever looking at, like, the calorie label or worrying about, like, let's say, fructose, knocking them out of ketosis or something like that?

No, absolutely not. And it didn't matter what it was, whether it was fatty meat, whether it was honey, whether it was fruit, if there was easy calories to be had, they would take advantage of it. And there was no, there was no cultural taboo around overeating. Like, overeating to them, to hunter gatherers is good. There's not any guilt associated with it. There's not any cultural breaks on it. When they have the opportunity to gorge themselves, they take that opportunity and they do it with relish. And when you think about it and you ask the question, why aren't these people obese? And there's really only one answer to that, and at least on the most basic level, and that is that those gorges are balanced by other periods of time when they're probably not getting as much calories as they would want. So on balance, they're in energy balance. But that's only because they're taking advantage of these opportunities to gorge. If they weren't taking advantage of that, they would probably not be maintaining energy balance.

And so it's basically just this entire concept of, like, feast and famine.

Exactly. So how do you deal with famine? You have to feast. And so I'm using the word famine, but most hunter gatherers don't experience, like, really bad famines, but they still have variability in their calorie intake and in how easy it is to obtain those calories. And so we know that calorie intake is a fundamental, one of the most critical drivers of survival and reproductive success. One of the main reasons for that is obviously your calorie needs and your nutrient needs go up when you're pregnant. And also in childhood, your immune system activity is very, very dependent on your calorie supply. The immune system is a calorie hog. And infectious disease in non industrial settings is a huge cause of infant and childhood mortality. Like, you know, something like one third to one half depending on society. If they don't have modern medicine, you're going to lose a third of your kids to disease. And the number of calories they're getting has a huge influence on whether they're going to survive or not. And so basically taking advantage of these opportunities to gorgeous is good for them. It's not bad for them like it is for us. It's good for them. It increases their ability to survive, it increases their ability to bear children and have those children survive. And so the, and so basically they are presumably wired in some sense to favor, to take advantage of these opportunities when they present themselves. And I think, I think this is a wiring that goes pretty deep. I mean, I think that we see the exact same thing today. Like what, what's a scenario? Imagine a scenario today that would be like maxing out the optimal value or the optimal foraging equation. It would be like free pizza or free food, you know, in general, like, how fast does free pizza disappear? It's gone. Like people will stuff themselves with it even if they're not that hungry, because it's like this amazing opportunity to get tons of calories at no cost.

That's, that's one of the issues that you get into in the book is it is so easy to fall into this habit or I guess this, this ancestral mechanism that our hunter gatherers would follow. Even though we're not actually starved, but we're still responding in a way that we would if, if we did have periods of famine, you know, like winding up at a buffet or being in a situation where we're just presented with a bunch of free food. Which happens to me, like occasionally I'll speak at an event and walk into my hotel room and they'll just be plates and plates of food and they'll say, oh, we're going to cover all incidentals, so order anything you want off the hotel menu. And all of a sudden I'm presented with that scenario where my ancestry wants to kick in and say, all right, there's like the, you know, the honey pot. Right. Dive in. But you have this concept that you present in the book called, I believe you call it episodic future thinking to reduce the intake of like tempting and calorie dense foods when they are presented to us in that type of scenario. Can you go into what exactly that is and how that works? Like how we can, how we can actually use that in a practical way?

Yeah, absolutely. So this is some research that I came across via Leonard Epstein, who's one of the researchers. He's a professor at University at Buffalo. He's one of the researchers who contributed quite a bit to the book. Really fascinating guy and fascinating work. So one of the topics I talk about in the book is how our decision making process frequently pits our present selves against our future selves. And this is something called. Well, yeah, it relates to a property called time preference. So generally we tend to shortchange our future self in favor of our present self. And I'll give you an example. If you are going to eat a donut, let's say I don't think anybody thinks donuts are healthy. The reason we eat donuts is because we are going after that pleasure value of eating the donut. That is a benefit that you experience right now. Whereas the costs of eating that donut, such as the financial expenditure and the future effects on your health and your waistline, those are all things that your future self incursions. And so you're basically making a decision to favor your present self over your future self, which might be you in a bathing suit next summer or, you know, you, whether or not you have to end up, you know, developing diabetes and getting, having to go on medication and the additional expense of all that, etc. Those are all cost to your future selves. And basically most of us have a time preference for our present selves. Actually all of us do pretty much to varying degrees. And what you see is that people who have a very strong time preference for their current selves over their future selves, they tend to weigh more, they tend to have more credit card debt, they tend to be in poorer health. Basically anything you want to look at that has to do with that has to do with delaying gratification. Those people are going to have poor outcomes. And so, and this makes a lot of sense because actually hunter gatherers lived in a very uncertain world. You didn't even know if you were going to be alive in five years. So why would you do something now? Why would you give up something now that would benefit you in five years if you don't even know if you're going to be alive. So, and also it's just very uncertain whether or not you're going to be alive. You can't really control your life that well. You can't make deals today. You can put money away in your retirement account and you can have reasonable amount of confidence that that money's going to be there in 30 years. I mean, that's crazy. Hunter gatherer can't make a deal with somebody and expect that person to pay them back in 30 years like that. There's just not that, that level of stability in their lives. And so, so basically it makes sense to have a time preference because the future is uncertain. But the problem is that that's been so wired into our brains, that time preference, that today we shortchange ourselves in a world where it makes sense to have less of a time preference. Today we have long lives, we live in a relatively stable society. There's a lot of accountability. It makes sense to care a lot about your future self, but we don't because we're not really hardwired to do that. And so one way to increase our ability to value our future selves, to increase our kind of like, intuitive ability to make decisions that favor our future selves, is this technique you talked about called episodic future thinking. And this is, it's a really, really, really simple technique. It's a fancy phrase that just means thinking about the future before you make a decision. So if you're about to make eating decisions, let's say you're at a buffet or you're in a coffee shop and there's pastries behind the counter that are tempting if you think about something that's going to happen to you in the future. So think about something positive like what you're going to do on your birthday, your, you know, your, your upcoming birthday, or some positive event that you're thinking about in the future that you're planning about in the future. It kind of revs up those parts of your brain that are, that weight the future intuitively and it increases your likelihood of intuitively making decisions that favor that value your future self, that don't shortchange your future self. And so it's been shown to work in an eating context. So with, I think the studies may have been done in women with obesity as well as children, when they use this episodic future thinking, it helps them make better food choices and it helps them eat healthier foods and eat less food in General, Yeah.

And the other interesting thing that I use that's somewhat similar is it might not be somewhat similar, but it's kind of this objective way to look at things is I imagine that I'm in a movie and that people are watching me in the movie, rooting for me as the. As the protagonist in the movie to make the right decision, right? So if I'm standing in front of the refrigerator at 10pm and I really want to eat a bunch of food, but I know I'm not hungry, I know I've had enough calories, I think, okay, let's say I'm watching a movie, I'm sitting in the theater, and I see me on the screen standing in front of the refrigerator. I'm going to be rooting for me to go get a good night of sleep and not stuff face so that I can stay lean for my competition and place high in a race, or so that I can have the body I want, or so that I can avoid the inflammatory effects of high blood sugar while I'm asleep. And once I think about that, it seems simple and stupid, but for me it actually works. Imagining that I'm actually an actor in a movie and that my role is to behave, so to speak, from a calorie intake or a cheating standpoint. But this idea of imagining the future is another one that it appears based on research actually is pretty compelling. Now, there are a few other things that you get into in the book that I found really fascinating. First of all, it appears that when you're talking about the ventral striatum and the release of dopamine from a lot of these highly palatable foods that we get exposed to. There's also another area of the brain that is the actual satiety center that causes us to feel full and that they've actually identified this somehow in rats. Can you talk about like the lesioned rats in the book and what this satiety center and the satiety factor is?

Yeah, absolutely. And I'll start off by saying that I think the term satiety in this context is a little bit of a misnomer. But I use it in the book because that is what it was called historically and basically what they found. So there was this, the first hint of this. There was this German professor named Bernard Moore who in 1839 published a case study on this woman who had spontaneously developed massive obesity, among among other symptoms. And she was taken into a hospital and. And I mean, she was just like, she was so fat that it was really striking. In the case report that he was, you know, went on and on about how remarkable it was, the quantity of fat that this woman had on her body. And he did an autopsy of her after she died, and he looked at her brain, and he found that she had a tumor in a part of her brain called the hypothalamus. And that was really the first evidence that. The first evidence that we know of that the hypothalamus plays a key role in regulating body fatness. And at this point in 2017, we have massive, massive amount of evidence supporting this, but that was really the first thing. And then that research continued through lesion studies where people would go in and they would destroy certain parts of the brain in different research animals. And they could kind of cross check this with human patients who naturally spontaneously develop tumors and other forms of damage in parts of the brain. And they found very similar effects. But basically, there was a part of the brain called the ventromedial nucleus, which is in the hypothalamus, that when you lesion it, animals would become enormously fat. So they would begin overeating tremendously and become enormously fat. And because destroying that makes animals overeat and makes them fat. They called the ventromedial nucleus, they called it the satiety center. So basically, get rid of it, you get fat. So they were saying, well, maybe the normal function of this is to suppress or constrain body fatness and appetite. And basically, there. There were a number of other models of obesity that emerged after that. So some of them were other lesion sites, Some of them were genetic models of obesity that emerged spontaneously. And basically, people started to figure out that this satiety center in the VMN and nearby areas was responding to a circulating factor. Basically, the reason those animals got so fat is because they lost their brains, their hypothalamus lost the ability to sense some circulating factor that was regulating body fatness. And this research suggested that, furthermore, not only was there a factor which they called the satiety factor that was in circulation that was affecting body fatness, furthermore, that it was really, really powerful. I mean, the effects that they would get were huge. Like animals that had a disruption either in the satiety factor or in its receptors or in the brain regions where it's received would become massively, massively obese. Whereas, conversely, if there was an excess of this stuff, animals would just lose all visible body fat and sometimes die of starvation. And so this was clearly a very central system in the regulation of appetite and body fatness. This is, this is clearly at the heart of why people have different levels of body fatness, why people eat different amounts. And research has continued to support that conclusion as we've understood more and more about that system. It turns out the satiety factor is a hormone called leptin. It's a protein that's produced by fat tissue in proportion.

So leptin is the actual chemical that is called the satiety factor?

Yeah, that was what it was called historically, before we knew what it was. So people knew a lot about leptin even before it was discovered. All this stuff that I was just talking about, about the effects on appetite and body fatness, that was all understood even before we had identified what the satiety factor actually was. But we knew it was in circulation. I say we, this was before my time as a researcher. They knew it was in circulation, they knew it was acting in the brain, and they knew it was acting to powerfully constrain body fatness and appetite. So leptin is produced in proportion to the size of fat stores. And it is a signal that tells the brain how much fat you're carrying. And basically its job is to prevent you from losing fat, prevent you from starving. And so if your body fat level starts to drop from your so called set point, or the point, the level of body fatness that your brain kind of quote unquote wants to maintain, it will initiate a starvation program. And that includes ramping up your appetite, ramping up your cravings. It reduces your calorie expenditure. It might make you feel sluggish and cold. These are symptoms that many people are familiar with if they have lost a substantial amount of weight. And so basically that starvation response is what kicks in in a really extreme form when you have animals that either don't have leptin or can't respond to it. So basically, even though they are incredibly fat, their brain thinks they're starving because their brain can't detect any leptin. So it thinks they have no fat and they're dying of starvation. And so essentially it kicks in, this huge starvation response. They get really hungry, they get cravings, they can't get full, their calorie expenditure is constrained. And so they continue to put on more and more fat and have these, have this elevated appetite.

And so in humans, what would be the equivalent of a VNM lesioned rat? Like how would that scenario be created in a human? Yeah, because obviously humans who overeat don't have lesions, right?

Yeah. So there's a couple different Ways. One way is you can have tumors. This is called hypothalamic obesity. So tumors that destroy that area can cause very similar effects to what we see in BMN lesioned animals. You can be born genetically without leptin. There are a few people who have been identified that lack leptin. So those are like some of those genetic models of obesity I was talking about earlier. These people are incredibly obese. They cannot feel full, and they cannot really be slimmed down. Like, it's almost impossible to cause them to lose weight. I mean, these are kids who are so fat that without treatment, they can't even walk. At age 8, they're in wheelchairs, like, incredibly fat. And all they think about is food. They're not really, as teenagers, they're not really interested in girls or dating or any of that. They just want to talk about recipes, they want to talk about food. It really. Food comes to dominate their mental lives, which I think serves to illustrate how deeply rooted these systems are in the brain. And so those are. Those are the extreme cases. Those are cases of brain damage or genetic mutations that really, like, throw a wrench in the whole system. But I think that so.

So why couldn't we just, for those people, just, like, give them a whole bunch of leptin?

Well, you can. For kids that lack leptin, you can, and they do, and it helps them a lot. If you give them leptin, they slim down and their food intake comes under better control and they turn into pretty normal kids. But the problem is that in people with common obesity, people with typical obesity, there's no leptin deficiency. People with typical obesity aren't lacking leptin. Their system, everything's there. Their hypothalamus is there. Their VMN is there. There's not any, like, massive damage. They are secreting leptin from their fat tissue. The amount of it in circulation is proportional to their body fatness, just like it's supposed to be. The problem is that their brain is not responding to that leptin as effectively as a person who's lean. So their brain, basically, they have this condition that we call leptin resistance. So their brain just can't hear the leptin very well. So it takes more leptin and more body fatness for the brain to feel like it's not starving. And for the brain to. Takes more leptin for the brain to restrain that starvation response that it would kick in if it thought you were starving. And so basically, your comfortable level of body fatness the level that you settle at if you're not really doing anything special to try to change it, is going to be higher when your brain can't hear that leptin very effectively. And we, we know that animals and humans that are obese that have obesity require a higher level of leptin to avert, to stop that starvation response. And so they literally have a higher set point. It's like turning up your thermostat. It's like turning up the heat on your thermostat. Your thermostat will defend that higher temperature set point.

Yeah. And is that why the people who are in the Biggest Loser regained all their weight? Because they, they actually, their bodies wanted to be at that original weight that they were at?

Yeah, I think that's a great example. And I talk about this a little bit in the book, and there's been some research on this too, but I think it's a great example because it's a really extreme example that really illustrates it clearly. So if you look at people on the Biggest Loser, you know, they're losing like £100, sometimes more. That's a lot of fat. And it takes, you know, as anyone who has seen the show can attest to, it takes a tremendous amount of effort on their part to get. To get there. But if you follow them up after the show, what you find is that almost all of them regain a substantial portion of that fat. Most of them regain most of it, if not all of it. And this is not just, you know, one or two people. This is, almost all of them are regaining most of this fat. And so, you know, if you look over a period of one or two years, and if you, if you see the interviews with these people, it's like, if you read the interviews, it's like they're just devastated. I mean, they feel very frustrated. They feel like they. Our failures, they feel like they were continuing to try. It's not like they just said, oh, the show's over. I'm going to start eating tons of pizza. Like, they wanted to maintain that lower weight they took. They made efforts to maintain that lower weight, and those efforts were not effective. And I think, I'm not saying they weren't effective at all, but they were insufficient to prevent substantial fat regain. And so I think this really illustrates the fact that a person who starts off with obesity and slims down to a lean level is not physiologically and neurobiologically the same as someone who is naturally lean. The person who started off with obesity is going to have a strong tendency to regain because they're generally going to be below the set point of their hypothalamus and they will have to fight a very strong starvation response to maintain that fat loss.

Now, in a case like that, would something like sensitizing one to leptin be one appropriate strategy to help to maintain the weight that you've lost? I mean, there's guys like Jack Cruz out there, for example, that has a protocol called the leptin reset protocol, you know, which is like a lot of protein with breakfast and not skipping breakfast, avoiding snacking, doing things like cold thermogenesis, using like, you know, lg, prioritizing sleep, messing around with like light and water and circadian rhythms. He has a, he has a whole protocol kind of spelled out for that type of thing. But would keeping one as sensitized as possible to leptin be an appropriate strategy for a scenario like that to avoid, you know, returning to that set point that your body wants to be at after you've lost weight?

Yeah, absolutely. I mean, I think that leptin sensitivity, that's really the key thing that we're going after, but it's also the thing that it's very hard to know how to affect. And all those things that you just mentioned that you know, are part of Dr. Cruz's protocol. I'm not aware of any evidence that any of those affect leptin sensitivity. In fact, I'm pretty sure there is no evidence.

Yeah, I don't think there's a lot of science and research behind that. I mean, I know that he works with people to lose weight, and I know a lot of people who do lose weight seem to keep it off. You know, I was just hanging out with, you know, relatively well known guy Rick Rubin, right? Like the Columbia Records music producer. And he's dropped down from like £400 and kept it off relatively well. And the guy actually does a lot in terms of, and he's been on the podcast before talking about this, maintaining a very normal circadian rhythm. And he does like sauna and cold treatments every day. And he even uses special blood sugar stabilizing supplements like bitter melon extract and cinnamon and apple cider vinegar, and pulls out a lot of stops, but has successfully not just kept off weight, but continues to lose weight. And I feel that a lot of those type of things seem to affect leptins.

Yeah, that's awesome. I mean, first of all, that's an impressive accomplishment. And you know, there are people who manage to do it. And I Think, you know, when I, when I start talking about this stuff, I think it tends to come across as doom and gloom to a lot of people. Like, it's hopeless. There's no point even trying. That's really not the message I'm trying to convey. I think that there are a couple things to consider here. There are going to be people who are atypical in any situation. And, you know, for any diet, you can find that one person who lost a million pounds on the diet. You know, that guy Jared lost I don't know how many pounds eating Subway sandwiches and walking around. That doesn't mean everyone's going to lose 200 pounds eating Subway sandwiches every day. But for any diet, you can find extreme responders. That doesn't necessarily mean that that is going to be the typical response for that diet and for that lifestyle. And I think that, you know, there's genetic variability basically every aspect of this body fat regulatory system. And one of the things that's probably genetically influenced is, is how hard that starvation response is going to fight you when you start losing weight. So some people, their brain's going to kind of shrug its shoulders and say, hey, you know, I don't really care that much. I'll make you a little bit more hungry. But I'm not really that worried about it. I think that's not common, but I think it happens. And then there are other people where it's like they're going to have to claw their way to get every single ounce of weight loss and then fight hard to maintain it. So I think there are differences like that. But, you know, the other thing is that the set point, the body fat set point that your hypothalamus is going to defend is not an immutable quality that can never change. So it's not something that's like genetically fixed that you can never influence. The set point is actually a flexible quantity that can be influenced by your diet and lifestyle. And I think this is where diet and lifestyle really comes in. And coming back to some of those things that you mentioned associated with Jack Cruz, there's not evidence, to my knowledge, that they impact leptin sensitivity, but some of those things can impact the set point, whether or not it's via leptin sensitivity specifically. And one of those things that I think presents a pretty clear case is protein intake. Higher protein diets have been shown to suppress appetite and increase metabolic rate, and particularly in people who are trying to lose weight and maintain a loss. And so basically what you see is that all of These hallmarks of this starvation response, such as increased hunger, increased cravings, reduced calorie expenditure, those things are all kind of blunted when you eat a high protein diet, which I think gives. It's not direct evidence, but I think it's pretty compelling indirect evidence that, that higher protein diets are affecting the set point. And another thing I talk about in the book is kind of the palatability and calorie density of the diet. There's a lot of evidence in animal models and some evidence in humans that diet palatability can have a large impact on the set point. So basically, when we eat food that tastes really, really good, we. Yeah, when we eat food that tastes really, really good, your brain is going to start actively defending a higher level of body fatness. And if we eat simpler natural foods, your brain is going to actively start defending a lower level of body fatness. And I think that's why we see a lot of people who, when they improve their diet quality, they will spontaneously lose weight. And it's not a struggle. It's not like I'm bean counting calories and forcing myself to eat less. Like they start eating a diet of whole natural foods, they're still eating to satiety, they're not feeling like they're struggling or depriving themselves yet that fat is coming off naturally and comfortably. And I think that's a situation you see a lot, especially in people who switch to a more unrefined ancestral type diet. And as you know, I think a lot of people who have switched to the paleo diet have experienced this very thing that I'm talking about. And I think so. I think there are a few different factors that go into that, such as the protein and the palatability and perhaps some other things.

Yeah, one other thing that you talk about in the book that I want to make sure we touch on. And then I know we're getting kind of long in the tooth with the length of the interview, but I wanted to make sure that we touch on this really quickly because it's super relevant and it's something that a lot of people I think know, but haven't seen the science behind. And that's this concept of this stuff called dexamethasone, which is a cortisol like drug that's typically used to suppress the immune system. And you state that when you give dexamethasone to folks you see, like kids, for example, they start to eat like crazy when they get this cortisol like drug put into their body and there's something about stress and cortisol that causes overeating. Well, what exactly is going on in terms of cortisol and excess calorie intake?

Yeah, absolutely. So, as you said, the cortisol, like drugs, can cause overeating and fat gain, and particularly gain of abdominal fat, which is the kind that you really don't want to gain, and corresponding deteriorations in metabolic health. Those are all things you see in high cortisol states. Whether it is induced by a drug or whether it's induced by a tumor in your pituitary actually is the most common cause. And so I think the thing that's really interesting about this is that it relates back to the relationship between psychological stress and eating, because cortisol is a really important stress hormone. And what you see is that people who experience psychological stress when. So there's different types of people. You know, all of our bodies respond a little bit differently to environmental inputs and challenges. And so certain people, when they're psychologically stressed, they secrete a lot of cortisol. Other people don't secrete quite as much. But what who secrete a lot is that they tend to overeat when they are stressed. So this provides a potential explanation for why stress causes overeating. Literally, stress causes us to produce a hormone that then goes into the brain and actually acts in the hypothalamus to reduce leptin sensitivity. And that causes us to eat more and gain fat.

So that's the mechanism is that when we talk about cortisol and we talk about leptin, the idea behind stress is that hypercortisolism can actually reduce your sensitivity to leptin. And so one of these strategies would be to actually engage in some either cortisol controlling type of strategies. And I have a crap ton of podcasts about that, from meditation to yoga to breathing to all sorts of different supplementation type of protocols and beyond. But also to be aware that if cortisol is higher, if we're in a stressed out scenario, one of the worst things we would want to do is be around highly palatable foods.

Yeah, that's. That's absolutely true. And, you know, just two, two additional details to flesh it out a little bit. One is that there's still some uncertainty remaining about the cortisol overeating story. So I think it's pretty convincing. But I don't want to say that it's 100% certain yet. I think we still need more research on it. The second thing I want to say is that it's not necessarily the only mechanism that can be at play. We also self medicate our stress by eating comfort foods. And those foods literally dampen the activity of the neural networks that are responsible for the feeling of stress, as well as the physiological effects of stress, including that cortisol release. So when we eat ice cream and brownies and whatever our favorite food is, that literally dampens that neural activity that causes stress and makes us feel better. And so that's another route is that when we're stressed, we can tend to gravitate toward eating too much of unhealthy food just because it makes us feel better.

Got it. So as you get into in the book, there's an actual biological mechanism related, you know, that. That draws this relationship and, you know, there's so much more in here that we didn't even take a dive into, you know, from. From, you know, more about the satiety factor to this special neuron that causes us to overeat. If. If you guys are listening in and you want the the complete treatise on everything going on in your brain when you eat food, you need to check out this book. So it's called the Hungry Brain. I've been taking notes as Stephane and I have been talking to everything from that book, the jungle effect that I mentioned, to Stefan's book, to this leptin reset that I talked about by Jack Cruz, to my podcast with Rick Rubin, and a whole lot more. So go to BenGreenfieldFitness.com HungryBrain if you want to check out all that stuff. And when you're over there, you can also leave comments or questions for Stephan or I, and I'll try and hunt down some answers for you. But in the meantime, at least grab the book because it's a. It's well worth a read. And I certainly folded over a lot of pages like I mentioned. Stefan, dude, thanks for coming on the show and sharing all this stuff with us, man.

Thank you for having me. It's good to be here.

All right, well, cool, folks. I know that that was a deep dive. Hopefully there's not too much smoke coming out your ears, but again, check out the book. There's tons of practical solutions in there as well. So until next time, I'm Ben Greenfield, along with Stephane Guillennet, the author of the Hungry Brain, Outsmarting the Instincts that Make Us Overeat. Signing out from BenGreenfieldFitness.com have a healthy week.

You've been listening to the Ben Greenfield Fitness podcast. Go to BenGreenfieldFitness.com for even more cutting edge fitness and performance advice.

Sam.