The Art of Manliness - #636： Why You Overeat and What to Do About It

00:00:00.000 Brett McKay here and welcome to another edition of the Art of Manliness podcast.

00:00:11.000 We all know the basics of losing weight, don't consume more calories than your body needs.

00:00:15.440 And yet many of us still overeat anyway, sometimes continually, sometimes to the point where

00:00:19.480 it leads to obesity, diabetes, and a significantly lower quality of life.

00:00:23.540 Why does our behavior betray our intentions to be lean and healthy?

00:00:26.500 My guest today argues that the answer lies in the ancient instincts of our brains that

00:00:30.540 no longer fit the environment of the modern world.

00:00:33.120 His name is Stephan Guillenet.

00:00:34.420 He's a neuroscientist, obesity researcher, and the author of The Hungry Brain, Outsmarting

00:00:38.580 the Instincts That Make Us Overeat.

00:00:40.460 We begin our conversation with what's changed in our country to turn obesity in an epidemic

00:00:44.220 and why Americans started to gain more weight in the 1970s.

00:00:47.700 We then dive into exactly how the reward system in our brain leads us to eat more than what

00:00:51.720 we need to, how modern manufactured foods like Doritos, one of my favorites, hijack

00:00:56.400 this reward system, and the factors that ramp up our cravings, including the buffet effect.

00:01:00.720 Stephan then explains how to push back on this desire to overeat, including reevaluating the

00:01:05.080 assumption that all your food you consume has to be tasty and delicious.

00:01:08.840 From there, we turn in the role that the hormone leptin plays in appetite regulation, how it can

00:01:12.860 make it hard to keep the weight you lose from coming back, and the best techniques to manage

00:01:16.660 this countervailing force.

00:01:17.900 We end our conversation with the role stress and sleep play and weight gain.

00:01:21.440 After the show's over, check out our show notes at awim.is slash hungrybrain.

00:01:26.400 All right, Stephan Guillenet, welcome to the show.

00:01:37.580 Thanks for having me on, Brett.

00:01:39.220 All right, so you are a neuroscientist who studies the central role the brain plays in regulating

00:01:45.100 hunger and how appetite leads to overeating and weight gain.

00:01:48.680 But before we get to those specific dynamics, let's take a big picture view of what's called

00:01:52.800 the obesity epidemic.

00:01:54.240 I think in the book, you said that we're at something like 30 to 40% of Americans are

00:01:58.420 obese or overweight today.

00:01:59.800 42% is the latest figures.

00:02:02.140 I mean, so what, when did that, it wasn't always like that.

00:02:05.020 If you, you highlight all this research going back to the early 20th centuries where it was

00:02:09.780 really low.

00:02:10.380 What were the numbers back then?

00:02:12.920 Yeah, that's correct.

00:02:13.860 It's been rising over a long period of time.

00:02:16.020 So if we go back, so the data, the best data that we have go back to the early 1960s.

00:02:22.540 Those are from large scale surveys conducted by the U.S. Centers for Disease Control.

00:02:29.140 And before that, the data gets increasingly sparse.

00:02:33.120 But we do have data going back to the late 1800s, early 1900s that paint a very different picture

00:02:40.360 than what we're seeing today.

00:02:41.560 So there was a survey conducted among white male Civil War veterans who were middle-aged

00:02:48.280 at the time in 1890 and 1900.

00:02:52.440 And what they found at that time is that fewer than one out of 17 of those middle-aged white

00:03:00.140 men had obesity.

00:03:01.940 Whereas today, if we looked in middle-aged white men, it would be something almost like

00:03:07.540 50%.

00:03:08.260 And so there's been a dramatic increase in the prevalence of obesity over time.

00:03:14.360 And what we see is that that has happened very gradually over a very long period of time,

00:03:20.240 but it's accelerated particularly between 1970 and 1980.

00:03:25.340 So between 1970 and 1980, we see a kind of sharp uptick in the prevalence of obesity.

00:03:32.500 And that is what we call the obesity epidemic.

00:03:36.340 And so what's going on?

00:03:37.260 What are the things that have changed starting in the 1970s that caused this sharp uptick?

00:03:44.040 Yeah.

00:03:44.400 So it's impossible to say with complete certainty because we're looking retrospectively and a

00:03:49.820 lot of things have changed and we're trying to figure out what is important and what's

00:03:53.740 not.

00:03:54.620 That said, I think we have some pretty good guesses.

00:03:56.860 And the first place to start is that our calorie intake has increased quite substantially

00:04:02.060 over that period of time.

00:04:04.040 So compared to the 70s, today we eat roughly 218 calories per day more than we did.

00:04:13.420 And it's actually, you know, that's a very simplified picture because what's really happened is that

00:04:18.440 some people are eating 400 calories more.

00:04:21.460 Some people are not eating any extra calories.

00:04:23.660 And that's explaining the divergence in weight that we're seeing between individuals over

00:04:29.160 that time period.

00:04:29.920 Because what you see, you know, if you're looking at the bell curve distribution of weight, what

00:04:34.680 you see is it's flattened out a lot.

00:04:36.500 So in other words, it used to be that most people were clustered around a leaner distribution.

00:04:45.000 And now we see there's this huge tail where you have 9% of Americans now have what would

00:04:53.160 be called extreme obesity, body mass index over 40.

00:04:57.240 So these are the people who really are at very high risk of health impairments and, you know,

00:05:03.920 being the folks that you see in motorized wheelchairs and that sort of thing.

00:05:09.620 And so it hasn't hit everyone the same.

00:05:13.460 It's really been this flattening out of the distribution over time.

00:05:19.440 And yeah, so the question is, what explains that?

00:05:22.320 Why did we start eating more calories?

00:05:23.980 And I think the answer is that we've seen profound changes in how we interact with food

00:05:29.160 over time in this country.

00:05:30.660 What we see over a long period of time, but particularly accelerating during that time,

00:05:36.020 is that we've increasingly outsourced food preparation to professionals.

00:05:41.320 So instead of cooking food at home ourselves, we are now buying industrially prepared food.

00:05:47.500 We are now eating out a lot more at restaurants.

00:05:50.860 We're essentially outsourcing our food prep to people who have kind of different abilities

00:05:56.040 and different incentive structures in how they prepare that food. 0.93

00:05:59.820 And it's also very, very convenient, which I think is important.

00:06:04.380 And one of the things that, one of the ways in which that has expressed itself is between

00:06:09.680 meal eating occasions.

00:06:11.620 So what we see is that that increase in calorie intake, most of that can be explained by the fact

00:06:16.940 that we're eating more between meals.

00:06:19.260 So we're snacking more, we're eating, we're drinking more sweetened beverages between meals

00:06:25.280 than we used to.

00:06:26.880 So overall, I think this paints a picture of really profound changes in how we're interacting

00:06:32.680 with food in this country in terms of how food is prepared, how we're purchasing it, and

00:06:37.580 how it's distributed throughout our day.

00:06:39.680 One other thing that I'll mention is that smoking rates declined quite a bit since about 1970.

00:06:48.980 And smoking, cigarette smoking, actually suppresses appetite and reduces body weight.

00:06:54.300 And so I think one factor that probably played a role as well, in addition to all these changes

00:06:59.680 in our food environment, is the withdrawal of that body weight suppressing effect of cigarettes.

00:07:06.100 Because most people smoked back then, you take that away, and you're going to accelerate the fat gain.

00:07:13.620 Right.

00:07:13.820 And also, instead of taking a smoke break, well, I'll go get a Twinkie or whatever.

00:07:18.180 It's something to do.

00:07:19.560 Could be.

00:07:20.020 Yeah, it could be.

00:07:20.840 Well, and besides that, you also talk about, you highlight research how we just move less.

00:07:25.220 We don't work as like, you know, back our great-grandparents, they were probably a farmer.

00:07:29.880 And today, we, I mean, now we just like, a lot of us are just working from home.

00:07:33.540 We just go from the bed to the desk in our office.

00:07:37.620 Yeah, that's absolutely right.

00:07:38.800 And I think that probably played a bigger role in the changes in weight that happened over

00:07:43.980 the first half of the 20th century compared to the last half.

00:07:48.220 Because, I mean, by the time you get to the 70s, most people had more sedentary jobs by that time.

00:07:54.080 But certainly, I mean, the earlier part of the 20th century, most jobs were extremely physically

00:07:59.020 intensive, you know, not just farming, but working in factories, that most of these things

00:08:04.580 were not mechanized, or they were only lightly mechanized.

00:08:08.300 So, you know, if you were working on an assembly line and in a plant producing cars, or even

00:08:14.640 just, you know, sewing clothing, or washing clothing, or, you know, almost anything that

00:08:21.520 you can imagine was pretty physically intensive.

00:08:24.380 And the things that we did at home were physically intensive, too.

00:08:27.720 Remember, we didn't have washing machines.

00:08:30.140 We didn't have dryers.

00:08:32.520 Most people didn't have cars for most of the first half of the 20th century.

00:08:37.880 So you had to, you know, get around by foot, or public transit, or even on a horse.

00:08:42.800 So just living life was more physically intensive.

00:08:47.120 A lot of the things that we had to do manually back then are now mechanized.

00:08:51.640 And so I think definitely physical activity is a factor, but probably more the changes

00:08:57.840 that occurred in the first half of the 20th century, I would guess.

00:09:00.940 All right.

00:09:01.060 So let's dig into why our brain wants us to eat more than we need.

00:09:06.120 And you talk about, it all starts, we have this reward system in our brain that sort of

00:09:10.740 kickstarts our desire to eat.

00:09:12.620 What's involved there?

00:09:13.680 What's going on with that reward system in our brain?

00:09:16.280 And what kinds of food does it want us to eat?

00:09:19.580 Yeah, so let me explain what the concept of reward is first.

00:09:26.460 Reward is essentially, food reward is the seductiveness of food.

00:09:31.120 So food, depending on its properties, has the ability to spark the motivation to eat in us.

00:09:38.660 So imagine you're sitting around and suddenly a pizza comes out of the oven and you smell

00:09:44.160 it and you see it and suddenly you really want to eat that pizza, that motivation, that desire.

00:09:50.680 So reward is that motivation, it's that desire, it's the pleasure that you get as you eat the pizza.

00:09:57.360 And it's also the learning, and this is something that happens beneath our conscious awareness.

00:10:03.040 We're not aware that this happens, but it's the learning that happens that causes your brain

00:10:07.720 to decide how motivated you should be in the future for similar types of foods.

00:10:14.200 And so essentially the brain is hardwired to learn to be motivated by specific food properties.

00:10:22.380 So these include fat and carbohydrate, like starch and sugar, and salt, and protein, and umami,

00:10:33.420 which is that meaty MSG soy sauce flavor that most of us are familiar with.

00:10:41.080 And essentially we are hardwired to prefer these food properties and we will seek them out and

00:10:49.700 we will learn over time which foods supply them.

00:10:53.040 And the way we do that is via a neurotransmitter called dopamine.

00:10:56.800 So when you eat, and this, you know, just in the last couple of years, this concept has

00:11:01.360 really been fleshed out.

00:11:02.460 So I'm really happy to be able to actually give more detail today, or at least a more complete

00:11:07.620 picture today than I even could at the time that I wrote my book a couple of years ago.

00:11:12.920 So essentially what happens is when you eat food, that food goes down into your digestive

00:11:17.380 tract and your digestive tract through receptors in your mouth, but mostly in your small intestine

00:11:24.060 detects the composition of that food.

00:11:26.540 So there are receptors that are detecting carbohydrate and fat and protein and salt and, and everything.

00:11:33.500 And those receptors then send signals up to your brain.

00:11:38.740 And this is all non-conscious or at least most of it's non-conscious stuff happening in your

00:11:43.440 small intestine is non-conscious.

00:11:45.220 It sends signals up your vagus nerve, which is a information highway between your guts and

00:11:51.680 your brain.

00:11:52.460 And it sends that up and it informs your brain of the things that are in that food.

00:11:57.460 And depending on the concentration of those things in the food determines how much dopamine

00:12:04.380 gets released in your brain.

00:12:06.160 So essentially your brain says, oh man, this pizza has tons of fat and carbohydrate and

00:12:11.100 salt in it.

00:12:11.880 So I'm going to release a bunch of dopamine indicating high concentrations of those desirable

00:12:17.080 nutrients.

00:12:17.900 And what that's going to do is it's going to motivate you to eat more pizza and it's going

00:12:22.400 to set your motivational tone for the next time you encounter pizza.

00:12:27.020 So the next time you encounter that pizza, your brain knows your brain has correlated the

00:12:34.500 fat and starch and salt with the appearance of the pizza, with the smell of the pizza.

00:12:42.040 So, you know, the triangular slices, the greasy box, where you ate it, who you were with, what

00:12:47.860 the situation was, everything, those become motivational triggers.

00:12:51.700 So then next time all you have to do is smell the pizza or see the pizza or be in the conference

00:12:59.180 room where you normally eat pizza and that triggers the dopamine again and that gets your

00:13:03.780 motivation going.

00:13:05.080 So that triggers, you know, another way of saying that is that you experience a craving.

00:13:10.480 Once that dopamine hits because it was triggered by that cue that your brain had previously associated

00:13:17.160 with carbohydrate and salt and fat, once that cue is experienced by your brain, then it triggers

00:13:26.000 the motivation to eat.

00:13:27.220 So that's basically how your brain learns to motivate you to eat food properties that were

00:13:35.340 important to the survival of your ancestors.

00:13:37.360 Because you have to remember these food properties to our distant ancestors, hunter-gatherers would

00:13:43.540 have been extremely critical for them to obtain in a natural environment because most of them

00:13:48.500 are supplying the calories that they need to fuel their bodies, and then others are supplying

00:13:54.100 critical nutrients that are scarce in natural, unrefined plant foods like salt.

00:14:00.100 You know, salt is not something you can just get very easily by going out and eating random,

00:14:05.220 you know, edible foods in the forest.

00:14:08.220 Salt is something that you need to kind of seek out either through seawater or mineral deposits

00:14:14.960 or different cultures had different ways of getting it.

00:14:18.260 But, you know, as mammals that sweat, we actually lose a lot of salt for, you know, a mammal.

00:14:26.740 And so we have this special need for it.

00:14:29.240 And that presumably explains why salt, sodium chloride is literally the only, you know,

00:14:35.220 micronutrient, that is to say, vitamin and mineral that we can actually taste in our food.

00:14:42.340 All right.

00:14:42.500 So just to recap here, there's particular foods, fatty foods, sugary, salty, umami foods.

00:14:48.480 Back then, those were essential for our survival.

00:14:51.320 Today, and so our brain, as a consequence, has this system in place where dopamine is released

00:14:56.980 so that whenever we encounter these foods, we learn that, okay, we should want this.

00:15:02.320 And so every time we see it, we have that desire, that craving.

00:15:05.620 I think it's important to think, like, oftentimes people think of dopamine as the pleasure neurotransmitter,

00:15:09.560 but it's not.

00:15:10.660 Like, it's just about wanting.

00:15:12.480 You can, like, eat something and, like, not really like it, but you can still want it.

00:15:16.120 Like, a drug is a good example.

00:15:18.000 Like, you might not like the drug, but it causes that dopamine, so it makes you want to

00:15:22.280 want the drug over and over again.

00:15:24.060 Exactly.

00:15:25.540 Yeah.

00:15:25.840 And thanks for bringing this up.

00:15:27.360 So this idea that dopamine is the pleasure chemical is an idea that originated in the

00:15:35.060 scientific literature.

00:15:35.920 It was a hypothesis that was proposed decades ago and quickly refuted, essentially.

00:15:43.220 But it got, it kind of, like, dug in its heels in the popular mind, and it's been self-sustaining

00:15:49.340 since then.

00:15:50.340 So you see this claim a lot in the popular press, but really the evidence doesn't support it.

00:15:56.320 Dopamine is really all about motivation.

00:15:58.820 Dopamine is what causes cravings.

00:16:01.960 It's what causes you to want things at a really visceral level, you know.

00:16:07.160 It's not the abstract wanting, it's the really visceral craving-type wanting that dopamine

00:16:13.560 mediates.

00:16:14.460 And it also mediates that learning that teaches your brain how to crave in the future.

00:16:20.660 And I want to mention, you know, while we're on this topic, I want to mention that, as I

00:16:24.860 said, the concentration of these dopamine-stimulating nutrients determines our motivation levels and

00:16:31.320 how strong our cravings are, and also when you put them in combination.

00:16:35.480 So when you mix the fat with salt or you mix the fat with sugar, that's a lot more tempting

00:16:43.680 than if you're eating those things alone.

00:16:45.620 So think about, like, eating a bowl of ice cream, think about you subtract the sugar, or

00:16:51.660 think about you subtract all the fat.

00:16:53.620 That's not nearly as seductive as eating ice cream itself, which has the sugar and the fat.

00:17:00.380 And so today, essentially, through technology and affluence, we have refined the art or the

00:17:07.680 skill of, you know, refining these dopamine-stimulating nutrients to their utmost levels of purity and

00:17:17.220 mixing them together in ways that maximally stimulate our dopamine and create really strong

00:17:23.260 motivational drives, really strong cravings to eat those foods that are probably stronger than

00:17:28.660 anything our ancestors experienced eating whole natural foods found in their environment.

00:17:34.920 So I think, essentially, we have this situation where these foods that we've created are just

00:17:40.780 too good at doing what they're trying to do, and that's creating these negative consequences for us

00:17:48.160 in the form of overeating and eating less nutritious foods.

00:17:52.320 All right. So, yeah. So, like, that's the first problem there with how today's foods, like,

00:17:57.720 basically hijacks our reward system. I think you gave the example, like, the Dorito is, like,

00:18:01.820 the perfect combination of fat, carb, umami, and you eat one, and then you're eating the whole bag

00:18:08.860 because it's just that perfect combination of fat, carbs, and savoriness.

00:18:13.160 Yeah. I don't think I use that specific example in my book, but I think that is a relevant example.

00:18:19.080 Absolutely. If you deconstruct what a Dorito is, it's concentrated carbohydrate plus fat plus salt,

00:18:27.980 and then you have these other, you know, seductive flavorings on it as well that may contribute.

00:18:34.220 And, you know, a Dorito is very calorie-dense. The thing that affects calorie density the most is the

00:18:41.420 water content of foods. So, we think about an apple, it's, like, 80 plus percent water. We think

00:18:47.780 about a steak, it's, like, 75 percent water. Dorito has almost no water, right? And so, that's a very

00:18:56.160 calorie-dense food that is delivering this really concentrated combination of dopamine-stimulating

00:19:02.480 nutrients to your brain. But I think the one that takes the cake is actually chocolate. So, chocolate,

00:19:07.920 of course, contains very little water also. So, it's very concentrated, high in fat, high in sugar.

00:19:15.700 But the thing that puts it over the edge is it actually contains a habit-forming drug called

00:19:22.460 theobromine. Theobromine is similar to caffeine in that it's this, you know, mild habit-forming drug.

00:19:30.000 But, you know, that plugs right into the dopamine system too. So, when you get this really concentrated

00:19:35.520 combination of fat plus sugar and then you add a habit-forming drug on top of it, you've got a

00:19:41.700 really powerful combination. And I think that explains why in studies they find that chocolate

00:19:48.200 is the number one most craved food among the general population, but particularly among women.

00:19:54.600 All right. So, we've got really palatable food. And you've highlighted these studies that show that

00:19:59.600 food palatability or how tasty a food is, it has this combination of fat. That can affect whether we

00:20:05.020 seek it out. And I think you talk about this experiment where when people are given unpalatable

00:20:10.340 food. So, there's like this experiment done like in the 60s, I think, where there's like this machine

00:20:15.120 where it put out this, like, I don't know, it's basically like soiling green, right? Just like

00:20:19.800 this nutrition shake. And you could take as much as you want, but it had no flavor, but it had the

00:20:24.820 perfect combination of fats, proteins, carbs that you needed, but it wasn't good. And people really

00:20:31.360 didn't, they just drank as much as they needed and that was it. They didn't really, they didn't

00:20:36.180 overeat on this stuff.

00:20:38.040 Yeah, absolutely. This is, it's a pretty crazy experiment. Yeah, they had people in a hospital

00:20:43.360 that were inpatients for various reasons. And like you said, they gave them access to this machine

00:20:50.860 that dispensed, I think it was 7.4 milliliters of this bland liquid formula is what they called it.

00:20:58.580 Every time they pressed a button and it just dispensed it through a straw into their mouths.

00:21:04.480 And so, they could, you know, anytime they wanted to just grab this thing, press the button,

00:21:08.460 put the straw in the mouth and they got 7.4 mils. And yeah, so essentially you're stripping

00:21:14.700 everything pleasurable away from the eating process. And what they found was really interestingly,

00:21:22.780 people who were lean actually continued to eat their usual number of calories. So,

00:21:28.580 they continued to eat their maintenance calorie intake and their weight didn't change. People who

00:21:34.080 had obesity, their calorie intake dropped dramatically. And as you said, they were not

00:21:39.140 asked to reduce their calorie intake. They were just given the system and said, eat as much as you'd

00:21:43.780 like, however you need to feel full. And they, their calorie intake plummeted and they started

00:21:49.900 rapidly losing weight. And they saw this across several individuals and then it was replicated

00:21:55.740 by a later study as well. And yeah, so I mean, I think that just goes to show how much these

00:22:03.880 properties, these food properties contribute to our eating behavior. And there's plenty of other

00:22:09.440 research that supported that too. So, you know, there are randomized controlled trials, which is a

00:22:15.020 particularly rigorous type of study design where they give people different foods with different

00:22:20.500 types of flavorings, some of which are intended to taste good. And some of which are intended to

00:22:26.740 taste a little weird. And, you know, unsurprisingly, this is kind of common sense, but people ate more of

00:22:32.920 the foods that tasted good. And I should specify when you only gave them that versus only the other type

00:22:39.560 of food, they ate more total calories of the good tasting food. And these foods were nutritionally

00:22:46.720 identical. So, we're talking about literally just using different flavoring agents on the same

00:22:51.800 sandwich. So, the flavor itself, how much, how much you enjoy it, how much reward value it has, how seductive

00:23:00.240 it is, is a way that I like to put it, really does impact your food intake. And if we look across

00:23:06.120 typical diets, you can see that variation in how good people report the food tasting

00:23:13.620 has a large correlation with how much they eat at each meal.

00:23:19.280 We're going to take a quick break for your words from our sponsors.

00:23:22.280 And now back to the show. All right. So, not only is food today, the processed food,

00:23:27.240 it's designed, I mean, it's designed to be more rewarding. So, we eat more of it and our brain wants

00:23:31.640 that. So, that's one thing going against us. But another thing that's different about today's food

00:23:36.560 environment compared to, say, 50, 60, 100 years, 1,000 years ago, that we have, there's more variety

00:23:42.540 of food. And that's another factor. I think, what role does variety play in the neuroscience of eating?

00:23:49.660 Yeah, absolutely. So, one of the earliest things that alerted me to this was this really cool study.

00:23:54.880 I think Barbara Rolls was involved in this. At least, I think this study is really cool because I learned

00:23:59.920 something. But they had mice in different cages, or I think rats in different cages. And they were

00:24:07.760 giving them just regular rat chow. But what they would do is they would put, in addition to that

00:24:12.760 rat chow, they would put different tasty foods in to these rats' cages. So, I don't remember exactly

00:24:19.720 what they were, but it was like cookies and sausages and some other tasty food. And they would put them in

00:24:27.220 one at a time. So, if you just put cookies in, they would eat more and they would gain a certain

00:24:32.840 amount of weight. But if you put all three of these different types of tasty foods in at the same

00:24:38.480 time, so the cookies and the sausages and the whatever else it was, crackers, then they would

00:24:45.480 gain a lot more weight than if you had just put one food in. Even though, you know, the one food is

00:24:51.600 already quite unhealthy. It's already calorie dense. It should be perfectly fattening. So, it really was

00:24:57.420 the variety per se that was having a big impact on how much they were eating and how much weight they

00:25:03.820 were gaining. And to this day, the most effective way to fatten a wide variety of non-human species 0.95

00:25:11.980 is to put a variety of tasty human junk foods in their cage and let them eat as much as they want. 0.99

00:25:19.340 Literally, human grocery store food, the types that most of us would recognize as unhealthy,

00:25:25.940 is the most fattening food in the world to a wide variety of non-human species. And so, like, 0.91

00:25:33.360 I think it's pretty, I think that is a pretty good piece of evidence that it's probably a big factor

00:25:39.180 in fattening humans too. So, you can, you know, just to expand on this a little bit, you can take

00:25:45.020 rats, you can put them on a high-fat diet, they'll gain a certain amount of weight. You can put them

00:25:51.120 on a high-sugar diet, they may or may not gain weight depending on the study. But, and, you know,

00:25:56.880 you can even compare, you can combine fat and sugar and they'll gain more weight than just the fat alone.

00:26:03.680 But none of those diets even comes close to human junk food, to giving them access to a variety of human

00:26:11.660 tasty junk foods. It blows away any kind of macronutrient composition that you can put into

00:26:18.080 a rat pellet. So, it's really, it's about way more than just the nutrient composition. It's really about

00:26:25.760 the presentation and how seductive that food is.

00:26:30.300 And the research shows that the same thing happens with humans, right?

00:26:33.560 Yeah, yeah, absolutely. So, yeah, so it does work on humans. And this has been demonstrated in a

00:26:40.120 number of studies. I think Barbara Rolls is the researcher who spearheaded a lot of those.

00:26:45.740 And essentially, if you put people in a situation where they can eat foods, again, you can even do

00:26:51.640 this with nutritionally identical foods where you're only changing the flavoring. People will eat more

00:26:57.160 if you have a variety of different flavors than if there's only one flavor, even again, if it's

00:27:02.640 nutritionally identical. And so, we call this the buffet effect. When you go into a buffet, like most people

00:27:09.540 have had this experience where you go into a buffet and you end up just eating way more food than you

00:27:16.700 think you should. And that happens particularly more at buffets than in other settings. That's been my

00:27:23.060 experience. And I think that's been a lot of other people's experience. And the reason is that

00:27:27.980 incredible food variety. Our brains essentially are designed, for whatever reason, to have this thing

00:27:35.480 called sensory specific satiety, which means that we get satiated on a specific type of flavor profile,

00:27:44.300 but not necessarily on other types of flavor profiles. So, if you have your steak, you might

00:27:49.820 not want any more steak, or you might not want any more meat in general, but that doesn't stop you from

00:27:56.260 wanting more cake. Or if you have a bunch of cake, you might not want any more cake, you might not want

00:28:02.560 cookies, but maybe you still want steak. So, that's called sensory specific satiety.

00:28:08.280 And that explains, I think, goes a long way toward explaining the impact of food variety on food

00:28:14.140 intake and body fatness. I think we've all experienced that, the buffet effect. You just

00:28:18.560 feel gross and you're like, no, I got to try that thing because it's different. Or like, yeah, the

00:28:23.800 dessert. You've eaten a big meal like Thanksgiving, right? So, there's a lot of variety at Thanksgiving.

00:28:28.160 I mean, you're full. But then like the pie comes around like, well, I got room for pie, even though

00:28:33.240 you probably really don't.

00:28:35.380 Exactly. I mean, I think this is a really great example of how our food intake is not just determined

00:28:41.080 by our nutritional needs. It's not just determined by the nutritional composition of the food,

00:28:49.000 or the calorie value of the food, or just hunger in general. You know, a lot of people really focus on

00:28:55.840 hunger as a determinant of our food intake and body fatness and weight loss. And it is important,

00:29:02.260 don't get me wrong. But hunger is not the big picture. It's, excuse me, it's not the only part

00:29:07.680 of the picture. So, yeah, think about you're at a restaurant and you've just had a meal of you had a

00:29:14.240 steak and a potato and a salad, and you're full. You've eaten already probably more calories than you

00:29:19.900 needed to eat at that meal. You're totally full. If someone put another piece of steak and another

00:29:26.500 potato in front of you, you wouldn't touch it. You wouldn't want to touch it. Yet, the waiter comes

00:29:32.260 around with a dessert menu, and suddenly you're ready to eat a piece of cake, or you're ready to

00:29:38.580 eat, you know, a brownie and ice cream or whatever it is. And that's because of this sensory-specific

00:29:45.860 satiety, you're not full on cake and brownies, you're full on steak and potatoes. And also,

00:29:52.540 of course, you know, these are very, very seductive foods. Desserts are very, very seductive foods that

00:29:59.720 really spike a lot of dopamine. All right. So, we got two things. We talked about two things,

00:30:04.460 our modern food system. Calorically dense, high reward food, a variety of it. And the other thing

00:30:09.920 that's changed compared to, say, our ancestors is that food now is readily available. It's easy to

00:30:14.620 access. All this stuff is easy to access. You know, before, if you wanted to get honey,

00:30:18.940 you'd have to, like, find a beehive and then stick your hand in a bunch of angry bees and get stung.

00:30:24.780 Today, like, I can just drive, I could walk over to Quick Trip and get a taquito and pay just,

00:30:29.900 like, a buck fifty for it. Absolutely. Yeah. And I think that is especially apparent if we're

00:30:35.480 looking over very long timelines of human history, like what you're talking about. If we're,

00:30:40.820 if you're a hunter-gatherer, you have to put in a tremendous amount of effort to get your food.

00:30:46.080 That is literally your job, getting and preparing food. That is what you spend hours on every day.

00:30:52.080 And it requires a lot of time and also a lot of effort to make that happen. And that's what our

00:30:58.200 motivational systems in our brain are tuned to. Our brain is calibrated to create enough motivation

00:31:05.160 to make you walk or jog five to eight miles a day, climb up trees, get stung by bees to meet your

00:31:13.420 calorie needs. That is what your brain is calibrated toward to in terms of generating motivation to get

00:31:20.760 food. But today, the effort barrier is so low, but we still have that same eating drive. And so, you know,

00:31:29.920 something like what we call gluttony today, I think is a really instructive example. We have a,

00:31:36.620 you know, I can't speak for all cultures, but at least in prevailing Western culture, we have this

00:31:42.180 negative judgment around gluttony, this word gluttony, you know, overeating. This is something

00:31:48.500 that we think is bad and we try not to do it very much. You know, we feel guilty about it. But if you go

00:31:54.260 back to hunter-gatherers, there's no such thing as gluttony. Like for them, eating as much as possible

00:32:01.260 is awesome because it's really hard to get that food. So when you get the opportunity to get a

00:32:06.600 really easy win and eating, you know, tons of honey or tons of oranges or tons of fatty meat,

00:32:12.840 you're going to take it and that's good. There's no downside because you're making up for other times

00:32:19.040 when you might not get as much food or when it might be harder to get food. So like this

00:32:24.180 idea of gluttony, I think really highlights this disparity between how our brains are set up and

00:32:31.580 how our modern food environment interacts with us. Like that's essentially us trying to culturally

00:32:36.860 protect ourselves against this issue that we're faced with. So yeah. So I think that today, you know,

00:32:44.700 it's obvious to anyone, I think you walk into a grocery store and there are many options for food

00:32:51.000 that you really have to do little or no work to consume. We eat out way more than we ever have in

00:32:58.240 human history. In the United States today, we spend about half of our disposable, half of our food

00:33:07.940 related expenditures is on food eaten away from home, like restaurant food, fast food. Whereas

00:33:14.280 we only spent about a 10th of our food related expenditures on food away from home back 140

00:33:22.540 years ago. And we have data going back that far and that's what it suggests. So there's been profound

00:33:30.000 changes in the convenience of food in this country. And essentially your brain, whenever you're thinking of

00:33:36.280 doing anything, whether it's shopping or negotiating for a job or making food decisions, your brain's

00:33:43.380 always doing cost benefit analysis. So it's saying, what is the benefit of this food in terms of its,

00:33:50.520 you know, calories and how seductive it is? And what are the costs in terms of how hard I have to work

00:33:56.180 for it? How much money does it cost? And how much time is it going to take me to do this? And essentially

00:34:03.500 the costs of food in terms of, again, the money and the time and the effort cost have gone way down

00:34:11.740 over the course of human history, but particularly over the last century. I mean, food is historically

00:34:17.980 cheap in the United States. We, we like to complain about the cost of food, but it's literally cheaper

00:34:23.800 than it's ever been in all of human history. We spend about 10% of our disposable income on food today.

00:34:29.940 So I think that all of the downsides, all the costs of eating that we would have experienced

00:34:37.520 historically have been minimized to an extreme degree. And there's benefits to this. You know,

00:34:42.320 there's way less starvation happening in the United States than there was a hundred, 200,

00:34:47.640 300 years ago. And that's a wonderful thing. So I don't want to present this as it's all a bad

00:34:54.600 thing, but there have been costs. And one of those costs is obesity.

00:35:00.340 Well, it sounds like just from understanding the rewards from our brain and like the things that

00:35:03.760 influence it. So the, the palatability of the food, the variety of it, the cost of it. I mean,

00:35:09.240 from there people can, there's insights there on how you can control your eating. So you're not

00:35:13.440 consuming as many calories. And it sounds like, you know, don't buy the cookies and potato chips,

00:35:17.940 stick to like basic foods like oatmeal, rice, meat, eggs, don't have a huge variety of, I mean,

00:35:25.540 variety of bad food and then make it like, keep the, make it easy to eat the good food and harder

00:35:30.540 to eat the bad food. Absolutely. Yeah. And some of this stuff that we're talking about boils down

00:35:36.020 to pretty simple principles that aren't going to, you know, be a big shocker to anybody like eat

00:35:41.160 simple on less processed foods. But I think, you know, there are some things that are a little bit

00:35:47.840 more counterintuitive to people. Like, I think people are used to thinking that their food has

00:35:55.180 to be delicious every time. And I think that that is an idea that's kind of been drilled into us by

00:36:02.960 diet marketing. Like this, every diet, no, what diet is going to say, Hey, this is, you know,

00:36:10.280 this is a bland diet. No diet is going to say that they're all going to say, you're going to be

00:36:14.640 eating the most delicious food you've ever eaten in your life. And you're going to be losing weight.

00:36:19.020 You know, it's part of the sales strategy, but the truth is that that deliciousness itself is

00:36:24.700 one of the things that is holding you back from eating a more appropriate number of calories for

00:36:31.240 your weight loss goal. And so that is one thing that I think is a little more counterintuitive. And

00:36:37.140 of course we have, the diet has to be satisfying enough that you stick to it. I think, you know,

00:36:42.600 you don't want to eat a diet that just tastes bad. You're not going to stick with it. But I think we

00:36:46.660 can eat things that are simple and satisfying that are more like what our distant ancestors used to

00:36:51.800 eat. Just simpler things like, you know, simply prepared meats and vegetables and nuts and fresh

00:37:01.460 whole fruits and limiting added fats, limiting added sugars and other things that are very concentrated

00:37:08.400 dopamine stimulating nutrients. And to this, I was going to say to this idea of, you know,

00:37:13.880 your food doesn't have to be delicious all the time. You highlight this tribe, the Kung San. 0.90

00:37:19.380 I think they're in the Kalahari Desert. And you point out that, you know, they occasionally they

00:37:24.740 get some honey, they get a truffle, which they just, they gorge on. But it says, but due to the

00:37:29.800 limitations of living in a natural environment, they ate certain other foods daily without much

00:37:34.580 enthusiasm. It's just like, yeah, it's just fuel. Yeah, absolutely. And that's what you, that's

00:37:40.500 what you see in hunter gatherer cultures. Like I think most people in, you know, cultures like ours

00:37:49.840 are accustomed to having their palates entertained with everything that crosses their lips. But I think

00:37:55.760 most of us would be severely disappointed by the diets that hunter gatherers eat. I mean, if you 0.94

00:38:02.080 actually really look at what hunter gatherers eat, and again, this is what all of us ate prior to say

00:38:08.760 12,000 years ago, they're, you know, they didn't have ovens with for controlled temperature baking and

00:38:15.980 roasting. They didn't have, they weren't sauteing onions. They didn't have sugar and white flour and

00:38:22.420 added fats. At least most of them didn't have added fats. And so, you know, we're talking about taking a

00:38:29.440 piece of meat and throwing it on the fire with no salt on it or burying it in, you know, in the sand

00:38:35.700 next to the fire. We're talking about eating fresh fruit. We're talking about eating plain roasted

00:38:41.280 nuts with nothing on them. We're talking about eating tubers that had weird off flavors. Like

00:38:47.820 sometimes they were bitter. Sometimes they had other, you know, flavors that we wouldn't necessarily

00:38:53.080 enjoy. Tons of fiber sometimes in these tubers so much that you might have to spit out a lot of it

00:38:59.400 as you're eating it. Some of the fruits they ate were not very sweet. Depends on the fruit. Some of

00:39:04.840 them were sweet. Some of them weren't, but some of them were not very sweet. And so you're eating this

00:39:09.840 like, you know, kind of tart, not very sweet, fibrous fruit. So like, that's a lot of what they were

00:39:16.480 eating day in, day out. And so that's not to say that they never had foods that were tasty. Again,

00:39:21.680 sometimes they did, but I think that overall the diet was a lot less seductive, a lot less

00:39:30.120 entertaining to the palate than what we eat today. And that's not surprising. Today we have incredible

00:39:35.100 control over what passes our lips. You know, our distant ancestors, they ate what was available or

00:39:40.480 what grew well in their area. But today we can refine things. We can extract the dopamine stimulating

00:39:48.100 sugar or MSG or, you know, starch or fat or whatever it is from those whole natural foods,

00:39:56.440 concentrate them and combine them into these really delectable kind of art forms for the primitive

00:40:04.520 parts of our brain that judge these things. And so it's just a very, very, very different picture

00:40:11.480 that we have today.

00:40:12.640 All right. So we've talked about the food environment and how it is designed, basically.

00:40:17.320 It's like there's an evolutionary mismatch. Like our brain wants these things at certain

00:40:20.760 time in human history, that was good. But today it's just too abundant and it causes us to overeat

00:40:26.460 and we get fat. Then you also in the book talk about another part that's driving us to feel hungry or

00:40:32.960 not. And it's this hormone called leptin. I'm sure people who are listening to the show probably

00:40:38.140 heard of leptin. They've read some stuff about health and fitness online. But can you walk us

00:40:43.460 through like what is leptin and what role does it play in our desire to eat?

00:40:48.980 Yeah. So essentially leptin is a key piece in the system that regulates body fatness in humans.

00:40:56.260 And the way that system works is that I'll start with an analogy. So if you imagine a thermostat,

00:41:02.940 thermostat measures the temperature in your house. And then whenever the temperature deviates

00:41:08.200 from whatever the set temperature is, it will either kick on heat or it will kick on

00:41:13.800 air conditioning to bring it back to that set temperature. And that's called a negative feedback

00:41:19.060 system or you call it homeostatic regulation. And these things are pervasive both in engineering

00:41:25.360 and in biology. So there's tons of things like this in the human body. For example,

00:41:30.400 temperature regulation is a great example. So the way the system works for regulating body fat

00:41:38.400 is that you have this hormone leptin that is produced by your fat tissue in proportion to its

00:41:45.160 size. So the more fat you have, the more leptin gets produced. That enters your bloodstream and it's

00:41:51.880 detected by parts of your brain. And those parts of your brain essentially compare it to

00:42:00.260 what they think it should be. And if your body fat level starts to drop, let's say you're going on a

00:42:08.580 diet and your body fat level starts to drop, the leptin goes down. Your brain is informed of the fact

00:42:16.660 that your body fat is going down via declining leptin levels. And then your brain kicks in the

00:42:22.640 suite of responses to bring the fat back. So your brain makes you hungrier. Your brain makes you crave

00:42:27.860 foods more. Your attention is shifted to pay more attention to foods. You might find yourself having

00:42:34.720 a harder time walking by the cookie aisle. And at the same time, if you lose enough weight,

00:42:42.180 your metabolic rate also starts to decline. So your brain actually starts to shut down

00:42:47.700 your metabolic rate a little bit. Essentially, what your brain is trying to do is bring in more calories

00:42:53.100 and reduce the number of calories leaving so that you're able to squirrel away more into your fat

00:42:59.380 mass to bring that back to where it was. And the thing that really sucks about this system is that

00:43:05.040 it will actually regulate, it will defend against fat loss even in people who have obesity. So even in

00:43:12.500 someone who really carries more fat than is healthy, their brain is still going to defend their current

00:43:19.960 level of body fatness. So when your leptin level starts to drop, your brain is going to say,

00:43:24.280 no, I don't like this. And it's going to kick in that same starvation response because that's

00:43:30.040 exactly what I just described. It's literally a starvation response. It's going to kick in the

00:43:35.000 same starvation response that it would kick in if a lean person started to lose weight. So someone who

00:43:40.940 is actually really starving, like their body fat stores were depleted and they're actually under real

00:43:46.880 physiological threat, they're going to kick in a certain suite of responses. And of course,

00:43:52.340 this is all non-conscious. It's happening from non-conscious parts of their brain. They're

00:43:56.840 going to kick in this protective starvation response. Someone with obesity has the same thing 0.99

00:44:03.020 when they start to lose weight. So that's really something that's really challenging about how human

00:44:09.920 biology is set up. And so when you look at randomized controlled trials, again, that's this rigorous type

00:44:15.740 of study of different weight loss approaches. What we see generally is that people can lose weight on

00:44:22.820 almost any diet, but also on any diet, people will start to rebound after their period of maximum weight

00:44:31.980 loss. So generally in these studies, you see maximum weight loss around six months, and then people will

00:44:37.100 start to regain weight. And essentially what's happening, or I don't want to say this is the entire

00:44:42.320 picture, but a key part of what's happening is that people are losing the battle against their own

00:44:48.960 non-conscious brain that is trying to bring that fat back. They're losing the battle against these

00:44:55.680 brain regions that are actively undermining them and creating a struggle for them where they're having

00:45:03.580 to fight their own impulses to maintain that weight loss.

00:45:07.080 No, I think everyone who's tried to lose weight of experience, they lose the weight and then they

00:45:11.680 gain it back. And we've seen this dramatically on shows like Biggest Loser, right? People lose lots

00:45:16.480 of weight and then you follow up with them a year later and they've gained it all back. And I guess

00:45:21.260 that's leptin. There's no leptin there. And their brain's like, you got to get, you guys get back to

00:45:26.120 where you were. And so you start eating more and that's what happens.

00:45:30.800 Absolutely. And it's like stretching a rubber band. The harder you stretch it, the more resistance you

00:45:35.960 feel. And so for someone who's really lost a lot of weight, like people on The Biggest Loser,

00:45:40.980 they're going to have an extreme starvation response that is driving them back toward weight

00:45:46.040 gain. So, and as you said, you know, you follow up with these people a year or two later, most of

00:45:51.420 them have regained most of their weight. And, you know, I don't want to, a lot of times this comes

00:45:56.660 across as really negative and hopeless. I don't want to come across that way. I don't think that it is

00:46:02.620 hopeless to try to lose weight. But I do think that there are challenges that are because of how

00:46:09.080 the human brain and the human body is constructed. And I think it's really helpful for people to

00:46:14.100 understand those challenges because then they know what they're going to be up against. They're

00:46:18.360 prepared. They're not going to be, feel like a failure when they, when they hit those barriers

00:46:23.360 and maybe they'll have better tools to help overcome those barriers. And also, I think it

00:46:28.060 helps people not be as judgmental. Like if it were easy to lose weight, if we didn't have these

00:46:33.880 barriers, probably there wouldn't be very many people with obesity, right? I mean, this, these are

00:46:39.620 the things that are making it difficult and undermining people's well-intentioned efforts to lose weight.

00:46:47.540 Well, are there any insights from neuroscience that can help people manage that, that leptin battle?

00:46:54.040 I mean, is it just a matter of, okay, you know, it's going to happen. So you need to have a plan

00:46:57.680 and maybe you just have that plan and you stick to it, even though your body is like, no, eat the

00:47:03.200 cheesecake. Yeah. So I think, so there are a couple of different ways you can approach it. And these are,

00:47:11.460 you know, the first one I'm going to explain is a little bit of a caricature, but I'm just doing it to

00:47:16.140 prove a point. There's the kind of pure willpower approach where you say, Hey, I'm going to keep

00:47:22.520 eating the same foods that I've always been eating. Maybe my diet started off unhealthy. I'm

00:47:28.080 going to keep eating the cookies and the cake and the fried chicken. And I'm going to keep eating all

00:47:34.860 that stuff, but I'm just going to use portion control. So I'm going to try to eat half as much

00:47:39.340 as what I used to eat. And I think that's the situation where you're really going to be setting

00:47:45.440 yourself up for struggle, because when you do that, your brain doesn't like it. I mean,

00:47:52.760 the amount you were eating of those foods before was the amount that your brain was intuitively

00:47:58.260 telling you to eat, right? Because the way we eat is we sit down and we keep eating until we're full

00:48:03.760 and then we stop eating. That's the natural way of interacting with food for a human. And so you're

00:48:10.060 forcing yourself to not indulge your impulse to eat until you're full. And so you're setting up a

00:48:17.160 struggle between your, you know, higher order cognitive willpower parts of your brain and the

00:48:24.840 lower order, you know, intuitive impulsive parts of your brain. And that's a struggle that most people

00:48:30.200 just can't win in the longterm. Some people can, you know, this, it does work for some people and

00:48:37.600 they can do it. You know, some people just to have an iron will, but I don't think most people do.

00:48:43.480 And I don't think most people should expect themselves to, because it's just not really how

00:48:48.080 the human brain is set up. So I think a better way is to set up the situation so that you don't

00:48:55.400 have to exert all that willpower. So you set up the situation in such a way that you're actually

00:49:00.240 trying to change those impulses. You're trying to directly change how you're interacting with those

00:49:07.380 non-conscious part of the brain that are generating those impulses. And so that's just to give you a

00:49:13.020 couple of examples that are particularly important, changing your food environment so that you're not

00:49:18.060 feeding your brain food cues all the time. So again, when you see these, when your brain gets these

00:49:23.740 cues, like the sight of food or the smell of food, that triggers dopamine release, that triggers your

00:49:29.220 motivation to eat. So if you eliminate those cues, you're going to reduce your motivation to eat

00:49:36.880 more than you want to and things that you don't want to. It's the same thing as someone who's

00:49:41.680 trying to quit smoking. You don't leave packs of cigarettes hanging around the house. You don't go

00:49:45.960 to the places you used to smoke. You don't hang out with people who are smoking. You're trying to

00:49:50.340 eliminate those cues that are going to cause you to relapse into that dopamine-driven behavior.

00:49:56.600 So that's one thing. And then another thing is to eat foods that create greater levels of

00:50:03.000 satiety or fullness per calorie in the parts of your brain that process fullness, the feeling of

00:50:10.080 fullness. And the feeling of fullness that you feel is only loosely connected to the number of

00:50:17.040 calories you eat, but it's more tightly connected to food properties like how calorie-dense the food

00:50:23.440 is. In other words, how many calories per gram or per volume. So if you have food that is very,

00:50:31.080 very calorie-dense, like chocolate or bread is pretty calorie-dense, for the same number of

00:50:39.760 calories, it doesn't fill your stomach up very much. So 100 calories worth of those foods is not

00:50:45.140 very much volume. Whereas if you're eating a bowl of oatmeal or a piece of fresh fruit or a piece of

00:50:50.680 fresh meat, that is mostly water. So it actually, per calorie, fills your stomach up more, and that

00:50:56.600 sends signals up to your brain that actually makes you feel full. And so you end up feeling full having

00:51:05.040 consumed fewer calories. And again, since we sit down and just keep eating until we feel full, that's

00:51:11.160 the intuitive, natural way of interacting with food. You could eat half as many calories and feel just

00:51:18.000 satisfied if you're eating unrefined water-rich foods than versus if you were eating processed

00:51:26.720 calorie-dense foods. So that's another thing. So it's not just the calorie density, it's also the

00:51:32.020 protein content that makes you feel more full per calorie. It's the palatability, so how delicious it

00:51:39.080 tastes. The more delicious the food it is, the less filling it is per calorie. And the fiber content,

00:51:45.740 the more fiber is more filling. So just setting up your food environment, setting up the types of

00:51:52.680 foods that you're going to eat at a meal can actually help control those impulses in the first

00:51:58.000 place. So instead of struggling against hunger and struggling against cravings, you're actually

00:52:03.360 nipping those in the bud beforehand. So you're not having to day after day after day fight yourself

00:52:09.580 and whip out that willpower every time.

00:52:13.060 Well, two other factors you highlight about modern life that causes us to overeat is we don't sleep

00:52:19.840 enough. We're bad sleepers and we're stressed out. So what role does sleep and stress play in

00:52:25.480 our desire to eat?

00:52:27.340 Yeah. So sleep, there have been some studies. Sleep is pretty interesting. So you look at the

00:52:32.680 observational studies. So these are ones that just say, we're going to look at a bunch of people,

00:52:37.460 we're going to see how much they sleep and how much they weigh and how their weight changes over time.

00:52:41.960 And then we're going to see if there's any relationship between those two things.

00:52:46.280 And those studies find that actually sleep, short sleep is really well correlated with weight gain

00:52:53.020 over time. So people who sleep less than six or seven hours a night tend to gain more weight than

00:52:59.100 people who don't. And it's pretty big correlation. Of course, you might say, well, that could be

00:53:04.560 confounded. It's observational. What does it really mean? So there have also been these short-term

00:53:10.760 randomized controlled trials. Again, that's a really rigorous study design where they actually

00:53:16.200 restrict people's sleep in one group and not in another group. And then they compare their calorie

00:53:21.440 intake. And what they find is that when you restrict people's sleep, they eat more. And it's

00:53:28.040 pretty significant effect. I don't remember exactly what it was, but I get into detail in my book. It's

00:53:33.760 like 150 calories a day, something roughly on that order. And you're sleeping less. You're actually

00:53:43.300 burning a little bit extra energy too, but not enough to make up for the extra food that you eat.

00:53:48.740 And basically what it looks like is that it kind of turns on your body's, your brain's appetite

00:53:54.040 systems. When you put people in a fMRI, which is a kind of brain scan, and you look at their brain

00:54:01.500 activity when they're looking at images of food, they have more activity when they haven't slept

00:54:07.060 enough. So basically their brain is getting more excited about eating food than it would if they had

00:54:14.500 slept enough. And so essentially, yeah, this paints a picture where sleep causes you to eat more or

00:54:22.860 excuse me, insufficient sleep or low quality sleep tends to cause people to eat more. I don't want to

00:54:28.500 say that the evidence is super ironclad, but I think it's, it pretty, pretty strongly suggests that

00:54:35.100 is happening at this point. And then as far as stress is concerned, there are surveys that have been

00:54:41.900 conducted by, I think the American Psychological Association that suggests that people react

00:54:47.440 really differently to stress. So I think it's roughly 45% of people report overeating when they're

00:54:54.320 stressed. And then some 30 some percent of people report actually skipping meals. And so it has this

00:55:01.080 really different effect on different people, but a lot of people do start to over consume when they're

00:55:07.520 stressed. And they particularly fall back on comfort foods, which are usually these calorie dense foods

00:55:13.520 that we would normally think of as not very healthy and pretty fattening, you know, mac and cheese and, and

00:55:20.900 ice cream and cookies and that sort of stuff.

00:55:25.740 So bottom line there, get better sleep, practice good sleep hygiene, that can help, won't hurt, and then manage

00:55:31.520 manage stress in other ways besides eating food.

00:55:35.080 Yeah, absolutely.

00:55:36.820 Well, Stefan, this has been a great conversation. Is there some place people can go to learn more

00:55:40.020 about the book and your work?

00:55:42.440 Yeah. So the book is available from any place that sells books. Amazon is, is an easy place to get it.

00:55:50.180 My personal website is stephanguena.com or you can, if that's too hard to spell, you can do

00:55:57.720 wholehealthsource.org. That'll take you to the same place. I haven't been really active on my website

00:56:04.180 yet, but, or lately, but I do, I am fairly active on Twitter. Although since coronavirus, I haven't

00:56:13.280 really been, had as much time to write about health and nutrition topics. But I do also want to

00:56:19.100 recommend another website called Red Pen Reviews, which is an organization that I founded along with

00:56:25.300 some other nutrition experts that posts authoritative reviews of popular health and

00:56:32.200 nutrition books. And that's at redpenreviews.org.

00:56:36.340 Fantastic. I'm going to check that out. Well, Stefan Guillenet, thanks for your time. It's been a

00:56:38.900 pleasure.

00:56:39.400 All right. Thank you, Brett.

00:56:41.100 My guest today was Stefan Guillenet. He's the author of the book, The Hungry Brain. It's available

00:56:44.880 on amazon.com and bookstores everywhere. You can find out more information about his work at his

00:56:48.420 website, stephanguena.com. Also check out our show notes at awim.is slash hungrybrain, where you can find

00:56:54.080 links to resources, where you can delve deeper into this topic.

00:57:03.720 Well, that wraps up another edition of the AOM podcast. Check out our website at

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00:57:11.300 we've written over the years about pretty much anything you think of. And if you'd like to enjoy

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00:57:34.140 consider sharing the show with a friend or family member who you think gets something out of it.

00:57:37.700 As always, thank you for the continued support. And until next time, this is Brett McKay,

00:57:41.620 reminding you not only to listen to the AOM podcast, but put what you've heard into action.

00:57:53.080 Thank you.

00:57:55.080 Thank you.

00:57:56.080 Thank you.

The Art of Manliness - August 17, 2020

#636： Why You Overeat and What to Do About It

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