Feel Better, Live More with Dr Rangan Chatterjee - #191 The Truth About Calories with Dr Herman Pontzer

Episode Date: June 15, 2021

We’ve been told that the more we move, the more calories we will burn but today’s guest is here to explain why this way of thinking is wrong. Dr Herman Pontzer is an evolutionary biologist who researches how our deep past shaped the way our bodies work today.   Over the past 20 years, Herman has conducted ground-breaking research across a range of settings, including pioneering fieldwork where he lived with the Hadza hunter-gatherers in northern Tanzania. The Hadza are considered one of the last hunter-gatherer tribes in the world and provide a unique insight into the way we used to live.   In our conversation today and in his new book, Burn: The Misunderstood Science of Metabolism, Herman reveals his findings that despite the fact that Hadza men and women get between five and ten times more physical activity every day than most women in the USA or Europe, their total energy expenditure – the amount of calories they burn – is the same.   Exercise does not increase our metabolism. Instead, we burn calories within a very narrow range: nearly 3,000 calories per day for men and 2,400 calories for women, no matter our activity level. In fact, our metabolism - the way our body burns energy – affects every aspect of our biology from our pace of growth, reproduction and ageing to our weight and health. If we burn more energy in one area, our bodies will adjust by spending less energy in another. But all this doesn’t mean that you shouldn’t exercise. Far from it. Herman explains why movement is essential for humans.   We also discuss what the real paleo diet looks like and how many of us have been seduced into expecting every meal to be mind-blowingly tasty. Finally, Herman describes what it was like living with the Hadza and shares the lessons he learned from observing this ancient way of life. This is an enthralling episode and I hope you enjoy listening. Thanks to our sponsors: http://www.calm.com/livemore http://www.vivobarefoot.com/uk/livemore http://www.athleticgreens.com/livemore Show notes available at https://drchatterjee.com/191 Follow me on instagram.com/drchatterjee/ Follow me on facebook.com/DrChatterjee/ Follow me on twitter.com/drchatterjeeuk DISCLAIMER: The content in the podcast and on this webpage is not intended to constitute or be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or other qualified health care provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have heard on the podcast or on my website.

Even if you're more physically active, you're getting more exercise every day or getting more physical activity every day, that doesn't necessarily mean that you're burning more calories every day than someone who's more sedentary than you. I think that we need to be honest with people. I think that that's the best public health message is one that's going to be accurate to the science. And I think the science says that exercise by itself is not a very good weight loss tool. Hi, my name is Rangan Chastji. Welcome to Feel Better Live More. Hello, how are you doing? Thank you for joining me on my podcast. Today's guest is a researcher who I've been following for a number of years. In fact, he's a researcher who I referenced quite a

bit in my last book, Feel Great, Lose Weight, which was all about taking a sustainable and compassionate approach to health. You see, we've been told for many years that the more we move, the more calories we will burn. But this week's guest is here to explain why this way of thinking is simply not true. Dr. Herman Poncer is an evolutionary biologist who researches how our deep past shaped the way our bodies work today. And over the past 20 years, Herman has conducted groundbreaking research across a range of settings, including pioneering fieldwork where he lived with the Hadza hunter-gatherers in northern Tanzania. Now, the Hadza tribe are considered one of the last hunter-gatherer tribes in the world and really do provide a unique insight into the way that we used to live.

In our conversation today and in Herman's brand new book, Burn, The Misunderstood Science of Metabolism, Herman reveals his findings that despite the fact that handsome men and women get between five and ten times more physical activity every day than most men and women in the USA or Europe, their total energy expenditure, which basically means the amount of calories they burn each day, is the same. You see, his research is showing that we burn calories within a very narrow range, nearly 3,000 calories per day for men and 2,400 calories for women, no matter our activity level. You see, our metabolism, the way our body burns energy, affects every aspect of our biology, from our pace of growth, reproduction, aging, all the way to our weight and our health.

If we burn more energy in one area, for example, we exercise more, our bodies will adjust by spending less energy in another. But this does not mean that we should not exercise far from it. Herman explains why movement really is essential for humans. It's just not necessarily because of the reasons that we've already been told. This is a wide-ranging conversation about a whole host of different topics. We discuss what Herman learnt about real paleo diets when he was living with the Hadza. We talk about how we've all been seduced by society and marketing into expecting every single meal to be mind-blowingly tasty. And we also discuss Herman's key learnings from spending such a long time living with this wonderful tribe

and observing firsthand this ancient way of life. This is an enthralling episode and I really hope you enjoyed listening. And now, my conversation with Dr. Herman Ponson. I thought we'd start by getting straight to the heart of one of the bits of research that you've done. And that is that moving more doesn't necessarily mean that we are going to burn off more. I wonder if you could expand upon that, please. Yeah, yeah, that's right. So even if you're more physically active, you're getting more exercise every day or getting more physical activity every day, that doesn't necessarily mean that you're burning more calories every day than someone who's more sedentary than you. And the surprising that that kind of goes against what we're taught and what we're told, you know, both in nutrition

classes, if you take them or, you know, whatever sort of basic biology you might've had, or for that matter, you know, every website that talks about, you know, exercise as a way to lose weight or every glossy magazine, you know, just sort of self-help idea about exercise and weight loss. Um, and so it was a real surprise to us. And we came to this in a, in a kind of a funny way, we were doing work with really physically active, uh, communities in, in Northern Tanzania and, uh, measuring energy expenditures. And even though they're more physically active than us, they don't bring any different, you know, the energy expenditure per day is no different than you and me. Yeah. I mean, that's incredible to hear. I remember, I think it was two or three years ago when I first came across one of your research papers. And for me, it really helped me

understand what I see a lot in clinical practice. I thought, oh, it's so good to see some research there because you're right. There's this narrative within the public health community, within the scientific community, but it's gone beyond that. Even within just common everyday conversation with people, it's an assumption that we all have made that moving more will lead to burning off more. And that was what's so striking about those early research papers I read of yours, which is it's literally turning that on its head. So what you're proposing is pretty game-changing for a lot of people.

Yeah, I think so. I mean, it was game-changing for us. I can tell you that it was a total sea change in the way that I think about metabolism and in the way that I think a lot of us on the sort of basic research side of things, you know, I'm an evolutionary biologist, an anthropologist. I want to understand human evolution and how our deep past, you know, shaped the way our bodies work today. So I don't, I didn't come into this from a clinical kind of public health training. That's not my background.

So it's been fun sort of seeing that work be relevant and be in the discussion in public health. But we just wanted to understand how the body works from a fundamental level and to discover that there's this really basic assumption that we're all making that had never really been tested very well. And then to go and test it, this relationship between activity and expenditure, to go out and finally do that work and go, wait a second, this is not actually what we all assumed coming in, but what we were trained in coming in, that was really exciting. So I think it is a game changer. I think you're right.

Yeah. I think many people will have heard that and go, what does he mean? That if I move more, I know I can eat a Mars bar, I can see the calorie content and therefore you have it in gyms that therefore I can go and run for 45 minutes now or whatever the metric may be. So why don't we start right at, you know, right at the very beginning, you know, what is metabolism? How would you explain it to people? What are calories? And then from there, can you then take that next step and show us why moving more doesn't always lead to burning off more? Yeah, yeah, that's a great place to start. Metabolism is just the umbrella term for all the work that your cells do all day. You've got 37 trillion cells, and they all are doing work all day to

bring nutrients in, break them down, make other molecules get waste out. This housekeeping work that all of our cells are doing all day, all of that work requires energy. And so you could measure all the products that your cells make. And some people do that. They study metabolomics, it's called. And they're studying the proteins and enzymes that your cells are making. So you could measure the output, or you could do what a lot of us do, which is measure the energy expended for all that work. And it's basically two different ways of measuring the same process, which is all the work that those 37 trillion cells are doing. Now, most of that work, we're only dimly aware of, or maybe even not aware of at all. Things like your liver,

digesting your food and doing all the work that your liver does. Your brain, your brain burns 300 kilocalories a day. We're dimly aware of that if we're aware of that at all. You know, your immune system, reproductive system, all these things that your body's doing all day, most of it that you're not even, you know, conscious of, that's metabolism. Now, the parts of it that we're aware of are the exercise parts, right? When we get moving, we get sweaty, we get our heart rate up, we're aware of that part. And so we tend to sort of equate energy expenditure per day with the activity part that we can see or we can feel.

But in fact, even for somebody who exercises regularly, that activity portion of your expenditure is only, it's well less than half of how many calories you're spending every day is spent on physical activity. Most of it's spent on all the other stuff that you don't even know. That's metabolism. As somebody who's interested in human evolution and in evolution generally, we want to know how all those calories are spent. The activity part's cool, but we want to know about the those calories are spent and where the activity part's cool, but we want to know about the energy spent on reproduction and on immune function and maintenance, all the tasks that the body's doing. That's why I get excited about metabolism, because you're sort of doing the forensic accounting of how the body is prioritizing

the energy in and energy out. As somebody who's interested in human evolution, So as somebody who's interested in human evolution, you know, the genus Homo, we're all Homo sapiens, right? The genus Homo has been hunting and gathering since its inception, since it evolved two and a half million years ago. And so Homo sapiens, our species, is just the latest sort of twig off this large bough of the primate family tree, which is our bow, the genus Homo. To understand what humans are all about, and ecologically and evolutionarily, you need to understand what the body looks like, and acts like, and works like, and metabolizes like in a hunting and gathering population. That's what you need. That's the ecologically real sort of relevant lifestyle for us. But nobody had done it, right? So nobody had measured energy expenditures, total energy expenditures in a hunting and gathering population before. And so in 2009 and 10, Brian Wood and David Reikland,

two of my good friends and collaborators, we went to work with one of the last hunting and gathering populations on the planet, which is this community called the, their name is the Hadza. So the Hadza community in Northern Tanzania, they get, they eat all their foods are all wild foods, you know, plants and berries and tubers and wild game and honey. And they live in grass houses in the savannas in northern Tanzania. So they're a great, intact, wonderful, gracious, lovely folks living in northern Tanzania. And so we went there and we measured energy expenditures. And the reason we did it, the reason we did all the work to go and get the funding and take time out of our lives to go and live with these

folks for a long time, it was a long process, was to finally understand how many calories they spend every day, what humans spend every day when you're hunting and gathering. Okay. So how do men and women get about between five and 10 times more physical activity every day than men and women in the U S or Europe. So they're incredibly physically active. If you're a step counter, right. Uh, the Hadza get about 13,000 to 19,000 steps a day. Okay. Right. Plus they're digging up tubers and they're chopping into trees to get honey out of the, you know, cause the bees there put the builder hives in the, in the trees and. And, you know, they're carrying babies on their back. And I mean, it's a lot of work. So we were sure going into we were certain that they would be spending tons more calories every

day than we do in the West. That was a whole that was the premise of the work, right? Was that we were just going to go try to document that that deficit that we seem to have in the West. And instead, what we found was that their total energy expenditures, total calories spent per day is the same, indistinguishable from folks in the US and Europe. To get back to this, what is metabolism? The answer is, it's all those things. It's the activity, it's the immune system, but what's happening is, rather than just adding things. It's the activity, it's the immune system, but what's happening is, rather than just sort of adding them up in a kind of simple way, obviously, our bodies are able to

kind of manage and make the sort of economic decisions about how to spend those calories so that as someone who lives in a population like the Hadza actually don't have a top line number of calories per day that's any different than you and me, even though they're obviously spending those calories very differently, lots on activity and less on other stuff. Yeah, I mean, you call this the constrained energy expenditure model, don't we? If I run for one hour, therefore I have, you know, whatever, I don't even know how many calories that would in theory, you would burn off by doing that. But we sort of feel we can then go and eat an equivalent amount because we've just earned it. But it sort of works the other way as well, doesn't it? In terms of if we have overeaten, we then think that,

well, I can just go and I can go for a double run tomorrow or an extra long walk tomorrow to make up for it. But your research has shown that that just simply is not the case, at least for most of us. No, that's right. That's right. That's sort of the idea that you can run and earn your donuts, you know? And it's a dangerous way to think, actually, because when you don't understand how clever the body is about sort of manipulating your metabolism, and you have the sort of simple view of how it works, then yeah, then you can make sort of silly decisions like that. Like, oh, well, you know, I can have the box of donuts, because tomorrow I'm going to go on a longer run. And actually the body doesn't really work that way. The body is, it's a long-term kind of time frame that your body's

working under sort of a couple of weeks or even maybe a couple of months. And it's paying attention to how physically active you are. And if you change that, if you, if you start your exercise program and you're, you're exercising more, you might lose a little bit of weight early on. But as your body adjusts to that new level of activity, your total energy expenditure will sort of moderate and end up not a whole lot different than before you started. And now you think that you're earning all these donuts, right? Because you've been really good and you're doing all your exercises. But in fact, those donuts are going to pile on because your exercise expenditure isn't

doing what you think it does. It's not raising the total expenditure per day in the way that you think you would expect it to. So how much does a typical Western man, a typical Western woman burn off each day compared to the Hadza population? Yeah, so the biggest predictor of how many calories you're going to burn every day is how big you are, right?

Because I say we have 37 trillion cells, but obviously if we're bigger, we have more, and if we're smaller, we have fewer. And so a typical US or European or UK man burns about 3,000 kilocalories a day. That's about 11 megajoules, if you prefer to do megajoules. That has mostly to do with how big you are, how much you weigh, and particularly how much fat-free mass you have. Fat burns some calories it's actually it's an active tissue it makes hormones and that kind of stuff but not as much it's not nearly as active

as all your other tissues so we kind of fat is relatively quiet so it's mostly your fat-free mass uh that determines how much you burn women uh in the us uk other parts of the industrialized world, burn about 2,400 kilocalories a day. The difference in the amount of energy burned is because women are a bit smaller and tend to be a bit smaller. Also, women tend to carry a bit more body fat. For a given, if a man and woman step on the scale and they have the exact same total body weight, the woman probably will have actually a little bit less fat-free mass because women tend to carry a bit more fat. And therefore, her expenditures, we'd expect them to be a bit lower.

Not because men and women are fundamentally different physiologically. I mean, they are fundamentally different physiologically, but not because the expenditures are fundamentally different, just because the body compositions and sizes are a bit different on average. And then a Hadza man and woman, they tend to be a short-statured group of folks. And so they're a bit shorter on average than the typical US or UK man or woman. So they actually burn fewer calories. Women burn like 1,800 calories a day.

Men are like 24, 25. They're all shifted down because they're smaller bodied. But once you have correct, of course, we account for body size and composition whenever we do these analyses. Yeah. I so want this point, one of the central points of your work to come through to people, because I think it has, there's so many people who are struggling to lose weight. They are trying, they're torturing themselves, depriving themselves, punishing themselves all the time. And they're possibly doing it with the wrong equation in mind. So it's doubly tragic. A, it's not working. And B,

it's not working because actually, you're putting in all this hard work and effort. And B, it's like, it's not working because actually you're putting in all this hard work and effort. And actually that's potentially not the right equation to be using. So we just sort of break it down again. So we have, you know, let's say I'm a, you know, the typical Western man on average will burn off 3000 calories per day, right? So 3,000 calories is what they're going to use up. And you're saying a brain may use up 300 calories a day just to exist and do all the functions that we require off our brain, right? So there's 2,700 calories left on that very simple equation. So you're making the case, I think, that our immune system, our reproductive system, breathing, lungs, liver, spleen, basically all the organs in our body, just to do their job, they are chipping away at that. And so there's a huge amount of calories that are being burnt,

nothing to do with exercise, just to be alive and engage with life on a daily basis. nothing to do with exercise, just to be alive and engage with life on a daily basis. So then what happens? So for someone who then does go on a one hour run, and that is all they think is going to be utilising more calories, what happens in their body to keep that at 3000? On one hand, you're taking from here, but you're sort of pulling back somewhere else. Is that the idea? Yeah, that's right. That's right.

And a couple of things to be clear about. First of all, day to day, you might still fluctuate in your expenditures, right? So if you always run 10 miles on Tuesdays and you sit on the couch all your other days, then yeah, on Tuesdays, you'll burn more calories, right? Because your body can't adjust 24 hours. It doesn't adjust that quickly. It's more of sort of a lifestyle thing. Your body gets used to a lifestyle. So if you're the kind of person that's running, you know, 20 miles a week versus the kind of

person that's not, the person who's running 20 miles a week and your body's adjusted to that is spending, well, 20 miles. So it's about, um, it's about a hundred kilocalories a mile, right? On average, it's a good rule of thumb. So 20 times a hundred is 2000 calories a week. So 2000 calories a week is being spent on exercise for you. And that means that person is spending 2000 calories less on all the other stuff. And so, um, that's, what's exciting for me as an evolutionary biologist is figuring out what does the body prioritize, right? And so we know that, that some of the things that the body's reducing expenditures on, right? The things that it's taking away from

are some of the really good things that exercise does for you. So if you look at that person who's running 20 miles a week, they're going to have lower inflammation levels, but what is inflammation? Inflammation is actually energetically costly immune function that your body doesn't need to do, right? It's your innate immune function, always on high alert when it doesn't need to be. And it's actually bad for you to have high background levels of inflammation. Stress. If we look at people who are exercising versus those who don't, the people who exercise have a lower and shorter surge of things like epinephrine and cortisol in response to stress, right? And that's so they're spending fewer calories on that, on that stress response. And if you are over the course of the

day, you're constantly being on high alert because, right, that's not good for you either. So actually the suppression of that stress response is probably really good for you. Um, people who exercise a lot will have a healthy, I want to stress this healthy, but lower, uh, testosterone, estrogen, and progesterone levels on average, a bit lower, and that's going to help you save energy too. So your body's basic, and that's probably not the only thing that your body's doing. You might be making other sort of subtle adjustments about how you, you know, do you sit rather than stand, that kind of thing.

So your body's kind of making all these adjustments. And that's how you make the numbers work, that the people don't spend a 20 miler a week and the sedentary person don't have different expenditures overall because the 20 miler a week is spending less on these other things yeah i love it it just shows just how clever yeah and highly tuned our body so it's really humbling actually to think we oh you know we're smarter than our bodies well you

know we'll eat a bit more here run a bit more of it our body's like oh hold on a minute we're far cleverer than that. And I really, I love the fact that it seems as though we can prioritize different functions depending on what's going on. So, you know, in Bern, you write about not just the Hadza, you write about another population. It begins with T. I don't know how you pronounce it. Oh, the Chimani. Yeah. How do you pronounce it? Chim Oh, the Chimani. Yeah. How do you pronounce it? Chimani.

The Chimani. Yeah. And I found it fascinating that 70% of them have an active parasite infection in their guts. Yeah. And therefore, I think you're saying that actually, because there's that background level of infection and therefore inflammation, that the body is potentially diverting more energy towards the immune system and less to other parts of the body? Just taking a quick break to give a shout out to AG1, one of the sponsors of today's show.

Now, if you're looking for something at this time of year to kickstart your health, I'd highly recommend that you consider AG1. AG1 has been in my own life for over five years now. It's a science-driven daily health drink with over 70 essential nutrients to support your overall health. It contains vitamin C and zinc, which helps support a healthy immune system, something that is really important, especially at this time of year. It also contains prebiotics and digestive enzymes that help support your gut health. All of this goodness comes in one convenient daily serving that makes it really easy to fit into your life. No matter how busy you feel, it's also really, really tasty. The scientific team behind AG1 includes experts from a broad range of fields,

including longevity, preventive medicine, genetics, and biochemistry. I talk to them regularly and I'm really impressed with their commitment to making a top quality product. Until the end of January, AG1 are giving a limited time offer. Usually, they offer my listeners a one-year supply of vitamin D and K2 and five free travel packs with their first order. But until the end of January, they are doubling the five free travel packs to 10. And these packs are perfect for keeping in your backpack, office, or car. If you want to take advantage of this limited time offer,

car. If you want to take advantage of this limited time offer, all you have to do is go to drinkag1.com forward slash live more. That's drinkag1.com forward slash live more. Yeah, so the Shimani show this, There's another group where we've showed this even since the book has come out, actually. This stuff is moving so fast. It's really fun. But there's a group called the Chuar, which is another. They're also an Amazonian. So the Chimani live in Bolivia. The Chuar live in Ecuador. And they're both sort of Amazonian rainforest populations. And the Chuar, my postdoc at the time, Sam Urlacher, did this great study looking at children. And so we had Shuar children who are very remote. They do a lot of hunting and gathering. They do a little bit of farming, but a subsistence sort of simple traditional lifestyle.

And they have a high pathogen burden too. As you can imagine, if you live without any sort of modern medicines, barefoot mostly in really remote rainforest environments, you get a lot of parasites, you get a lot of bacteria. So your immune system's always active. And those kids, they have elevated basal metabolic rates, just like we see with the Chimani. But what's cool is with the Schwarz population, we've got children, so we can actually measure their growth while they're, because they're their kids. And Sam's able to show very nicely, if you look at the amount of immune activation, short-term immune function was something we call, we measure with CRPC, reactive protein, which is your body's first like, poof, you know, flush of immune response to a

really, you know, an acute stress. Kids who have that, they grow less in the subsequent couple of weeks. Kids who have these sort of long-term, you know, markers, there's different immune function markers that we can use to say, oh, that's a long-term infection. Oh, that sort of long-term markers, there's different immune function markers that we can use to say, oh, that's a long-term infection, oh, that's a short-term response. The long-term responses are correlated nicely with kids' long-term growth. So the kids that are constantly getting the most immune hit are backing off of their growth. And sure enough, when you measure expenditures, right, total energy expenditures, their total energy expenditures are the same as kids in the US or Europe, right? So these kids are playing with, in other words, these kids are all playing with the same energy budget. You all get the same number of calories and you can spend

it however you like. And if you spend it on immune function, you've got less to spend on growth. It has to be that way, right? And sure enough, that's what we see. So that prioritization is just super interesting to watch happen. Yeah, it's truly fascinating. And I mean, a little while ago, you mentioned that the Hadza tend to be shorter stature than let's say the typical Western population. Is some of this playing in there as well because of their lifestyles do you feel that maybe you know maybe we have

i don't know you know how how would you sort of yeah how would you put that together potentially well yeah absolutely i mean you know we don't know um so height is a great example of a trait that has both a really strong genetic component, right? Tall parents tend to have tall kids and a really strong environmental component, right? So there's, and it's this, it's not nature or nurture or nature versus nurtures. It's those things acting together. And so a population like the Hadza who tend to be short statured, they probably have a

lot of gene variants that would, you know, even if they grew up here in the West, they probably would end up a bit shorter on average. So it's not just the environment, but I bet it's playing into it. And, you know, probably the best example of this is something called the immigrant effect, which was documented pretty well in the, you know, in the mid 1900s, which is that when you see, you know, people who grow up, their parents grow up in a developing country, and without access to great medicines and without maybe access to great food, and maybe with a lot of physical stress in their lives, their parents grow up and they're relatively short. They move to a country that has better medicine, better nutrition, less work stress for the kids. And the kids are all a few centimeters taller than the parents on average, the immigrant effect.

And so that's been well-documented in people from lots of different parts of the world. You come from an energy-stressed environment, you move into an energy-rich environment, and your kids get taller, right? Because your kids are spending less energy than you were as a kid on all these other tasks. The idea for budget, I think, is brilliant. We've all got the same budget. So it's just where is your body going to allocate the resources? It's like, if you have a set amount of income, do you want to spend that on a small house and a fancy car? Or do you want it on a big house and a not so nice car or whatever? It's a beautiful way of thinking about the body, I think.

Yeah, that's exactly right. And in evolutionary biology, we are talking about energy budgets all the time. That's kind of how we think about it, right? And it's been fun too, because for some reason, in evolutionary biology, people got really comfortable talking about energy budgets in terms of reproduction versus growth growth or maintenance, like immune function versus growth and talking about trade-offs like that. And then somehow even in evolutionary biology activity was sort of this extra thing that could always get added on top. And you could always just fund that somehow separately. And I don't know how that thinking ever really took hold. But basically my work is saying, no, activity is

just another, you know, physical activity is just another act you know physical activity is just another activity that your body has to do that is just part of the mix it's just part of the budget you know and you kind of you know to expand or contract the budget much as hard you know you might you might push a little bit you might get a little but not not as much as you think you're getting because your body wants to kind of maintain the same budget no matter what. Yeah. Now, I think it's important that we're super clear. You're saying that exercising more, certainly in the long term, does not lead to us burning off more calories.

But you're not saying we shouldn't exercise. In fact, you're saying quite the contrary, that it's incredibly important. And I let this put in the book, which I'm just going to read if you don't mind. Those ancient adaptations have consequences for us today. Our bodies are built to move. In our modern industrialized world, free of the daily demands of foraging for our foods, we need to exercise for our bodies to function properly. It's a legacy of our hunter-gatherer past. Why is it so important that we move our bodies to function properly. It's a legacy of our hunter-gatherer past. Why is it so important that we move our bodies? Yeah. So this is another, I think, benefit of taking an evolutionary perspective. And that is to understand that our bodies and

our behaviors co-evolve. Okay. So a really nice example of this, it is in fish, right? You ever heard the example that people talk about sharks? If sharks don't keep swimming, right, they drown. A shark can drown. Why? Well, because, you know, ancient fish, all ancestral fish, when they evolved gills, evolved the ability to pump. They have muscles on the side of their gills that allow them to pump the water past their gills. So they can, most fish can just hang out still and just slowly pump the water past their gills. And, and they're fine because they can keep on getting fresh water, oxygenated water through their gills. Sharks and tuna and a couple of other sort of really active species like that, really physically active species. They're, they're, they're swimming so much that, you know, evolution actually favored reducing and then eventually kind of eliminating, because why spend on energy if you don't need to, on that musculature? Because they're moving all the time anyway, they could just kind of open their mouths and the water just kind of streams past their gills. And so now, if you take that same fish and you don't let it move, it dies, right? So it's the behavior, the swimming all the time, and the anatomy, which is this color pumping mechanism, or guilt pumping mechanism, co-evolving.

And that's a nice example that we can kind of all get a hold of, but it happens all over the place. This is how evolution always works, is behaviors and anatomies co-evolve. In humans, again, we've been hunting and gathering for two and a half million years. What does that do? Well, if you start hunting and if you start gathering in savanna landscapes where the food is scarce, you need to walk and just move a lot more to get your food. You have to, right? Food is farther apart to find. Animals will run from you. You know, they don't want to get caught.

And so hunting and gathering just requires a ton of physical activity. And your body, that's the behavior. And then the body adapts to that and gets used to that. And you just, your body, you know, you are born into the world with a body that expects to move. Just like those, you know, a shark is born in the world with a gills that expects to be pushed through the water. And now if we don't do that, if we rob ourselves of that constant activity that we normally get, yeah, bad things happen, right? Our physiology kind of expects that. And just like the shark that stopped swimming, bad things happen when we stop exercising because every aspect is actually hard to find. I would challenge anybody

to find a piece of your body that doesn't kind of, isn't contingent on that activity signal for normal function. It kind of gets everywhere. Yeah. And I guess that then speaks to how do we talk about physical activity to the population? How do I, as a medical doctor, talk about it with my patients? Because a lot of the time, it is done around fat loss, weight loss. And I think there's two sides to that coin a little bit. I've seen a few of your Twitter debates over the last few months on this. And, you know, it's quite a controversial topic as to, first of all, is exercise needed for weight loss? And therefore, depending on what your view is on that, how do we then articulate that message? So what are your sort of, having engaged in this for a few months and maybe several years,

what is your current view on that? Yeah. I think that we need to be honest with people. I think that that's the best public health message is one that's going to be accurate to the science. And I think the science says that exercise by itself is not a very good weight loss tool. And even exercise along with diet changes, exercise doesn't add a whole lot to the weight loss piece of it. Is that in the long term?

But because you're saying for a week or two or three weeks, you will get a benefit. You mean beyond that? Yeah, long term. I mean, there's great data on this that comes from all sorts of labs that aren't mine. So this isn't me speaking necessarily. If you look at the long-term effects of exercise interventions, exercise alone, the long-term expectation for weight loss is about two kilograms. So that's great. If you're looking to lose two kilograms, that's perfect. But most people who

are overweight or obese are looking to lose much more. And if you look at how much they're working, they sort of should lose much more, right? The tons of calories they're burning, but it doesn't work that way because the body adjusts. Okay. So I think sometimes my work gets sort of, I think, mischaracterized as saying that exercise isn't important. I think that's not what I've ever said. Exercise is super important. Now, do we exercise for weight loss? I would say this.

We don't exercise for weight loss, but you might exercise during weight loss for all the other benefits you get. But I think that if we want to move the number on the bathroom scale, and if we want to get fat loss to happen, then that has to be a diet approach, right? And, you know, when you go to any, well, look, I'm not a clinician, so I would defer to people who are in clinical practice like yourself. But somebody comes in and has a serious weight problem, and we think that, you know, we look at their blood profiles, we look at their blood pressure, we look at the direction things are going, and we say, look, this person needs to lose weight to get to a better place in terms of their health. There are a bunch of things you could prescribe, but wouldn't you make sure that you emphasize the thing that has the biggest effect, which should be that's diet, right? And so what I think is wrong, and that you see this in public

health messaging all the time, is this equivalence of exercise and diet. That's what bothers me, because that is not what the science says, right? So you say, well, you have of exercise and diet. That's what bothers me because that is not what the science says. So you say, well, you have to diet and exercise. And so if we say it like that, it sounds like maybe I'll just do one or the other and I could pick. Or it sounds like maybe exercise and diet have the same effect because one's energy in and one's energy out. And I could just decide to focus on one or the other. And that really isn't what the science says. The science says the diet is going to do all the heavy lifting and exercise to add onto that is fantastic and can do all kinds of good things.

But it's the diet piece that's actually going to change the number on the scale. Yeah. I really appreciate your perspective on that. The last book I wrote was actually about sustainable, responsible weight loss. And, you know, I quoted heavily your research in the exercise section. And I think I said at one point, you know, do you need to move more to lose weight? No. Would I recommend it? Absolutely not. And I'll tell you why. And I think this is, I guess, where my clinician lens comes in, more than a scientific lens, I guess. Or maybe, you know, slightly more biased towards what I see with people, which is there's a lot of stress eating, there's a lot of comfort eating,

there's a lot of eating when people are bored. You know, they know what they should ideally avoid eating too much of and what they should consume more of. Yet despite the knowledge, they're still doing it. What I found with exercise, particularly short bursts like 10 bicep curls every time you put a hot drink on in the kitchen, what I found is that there's no quicker way to boost people's self-esteem and their self-worth than getting their body swimming. So I find, although it's not necessarily there to help them burn off more calories, which it isn't, I find, especially if I make it manageable for that person and the concepts of their life, like I find it helps them engage and stay on track with kind of all the

other things that I'd like them to do. That's wonderful to hear. That makes a lot of sense to me. I would say too, just potentially, the advantage there is you haven't made exercise the reason that you're losing the weight. Yeah. Right. So if you disentangle those things, then you also disentangle the feeling of failure. Um, that I think is a real danger of exercise only weight loss approaches, which is if you're not losing weight, then you're doing the exercise wrong, or you're not trying hard enough, or it's somehow back on you that you didn't do the right thing. And I think that, you know, when we know that exercise alone is probably going to end up in pretty modest, if any weight loss at all, and all of it's going to come early, and you're probably not going to see much after that, then you're kind of setting somebody up for the realization in half a year or a year later of this exercise program that,

oh, this isn't really working anymore. And what is it? Am I doing something wrong? Or is this even worth doing? Right? And so when exercise gets tied to weight loss like that, I think that's a disservice to everybody. Yeah. And that's incredibly damaging for people's self-esteem because if they have diligently gone to the gym four times a week, pushed themselves, been on that treadmill for an hour four times a week, and they're not seeing the results, they do feel like failures. And what does that lead to? More comfort eating, which actually compounds the problem. And I think your research has so many implications for so many different aspects of health. You know, for me,

personally, one of the most funnest kind of conceptual points in the book was this idea that, you know, we've spoken about on the podcast before how chronic unresolved inflammation is at the root cause of, you know, many of these modern degenerative diseases, heart attacks, strokes, Alzheimer's, or, you know, rheumatoid arthritis, whatever it is. whatever it is. And I love this idea that because we have a fixed energy budget, if you were exercising more, then your body hasn't got as much budget left to give to inflammation. So it's actually going to drop down that kind of unnecessary, chronic, damaging inflammation. And I think, well, that's a very powerful reason to move our bodies more because we're going to reduce inflammation. So yeah, I want to thank you for that because that was a brilliant perspective that I absolutely loved. Well, thanks. Yeah. I mean, when you stop thinking about exercise as just, you know, again, how many donuts have I earned? And you start thinking about all of the things that it's doing internally to regulate that budget.

That's a lot more interesting, actually, right? Now you're thinking about, wow, gosh, what's exercise doing to reproduction? What's it doing to immune function? What's it doing to stress reaction? You can begin to follow the calories, do the forensic accounting of it, like I was saying. That's why it's so fun from just a pure biology point of view, but also, I think think powerful in terms of the clinical potential there. And I guess just staying on weight loss for one more point, and you did cover this in the book, this idea that when we move our bodies, that can have indirect effects on weight loss in the sense that it can regulate our hunger signals and our hunger cues a lot better, right? Yeah. And so this is an interesting thing too. A couple of sort of other, you're right. A couple of things to add to the weight loss story.

Exercise does seem to be really good for people to keep weight off. So when people have managed to lose weight, usually by diet, exercise has been shown to be a nice helpful tool for keeping the weight off. And so I think this has, again, that kind of regulatory aspect. It's helping you either, it's helping your sort of self-actualization about how much you eat, or it's helping your mood, or it's just helping your body, sort of the signaling in your body work better to match your intake at that new weight. There's also this piece of it where, and this is kind of not well understood because I don't think we've focused on this enough. And this is kind of not well understood because I don't think we've focused on this enough. If you look at people who are really, really inactive, there's a great example of this.

There's an old study in the 1950s done at a jute factory. This is the enormous jute factory and, you know, thousands of workers. And this is one of the first sort of epidemiological studies to try to carefully look at activity and weight. And so what they did is they looked at people's jobs, because thousands of people at this factory, there were lots of different jobs. And some of them were clerks, sort of pencil, paper pushers. Some of them were carrying bales of jute around. Some of them had enormously physically demanding jobs of cutting the bales. So you had this whole spectrum of how hard your job was. And at the very, very low end, uh, were the stall workers. And these folks, um, as I understand it, their job was to just sit, just sit in the stall. You don't even, you're not even walking on the floor, you know, taking boxes on your paper, on your clipboard, you're

just, just sitting. Um. And then they looked at weight, at body weight. And really, everybody's body weight is kind of the same from the pencil pushers, not the stall workers, but the typical clerks up through the hardest working laborers. Everybody's weight is more or less the same, except the people who really just were plugged in a box and just sat all day. They had weight problems and they were overweight or obese, depending on, I don't know where they would fall in the classification. And that says to me that if you completely take the exercise signal away completely, then you might have this dysregulation issue where you're, you know, that's going to lead to overeating. So in terms of exercise and

weight loss, yeah, at the very, very low end of, of exercise at the zero end of activity, there seems to be a real regulation issue there, um, that, that leads to overeating and who knows what else was going on in those folks lives but uh but yeah so you know i think this is something again to sort of explore not you know getting away from exercise as calories and getting towards exercise as regulation i really want to talk to you about your experience in tanzania because you know i've i've read a lot of previous research studies on the had so they seem to be studied a lot yeah um yeah it's true there's a lot of there's a lot of previous research studies on the HATTA. They seem to be studied a lot. Yeah, it's true. There's a lot of microbiome studies on them, which I've written about before. There's a lot of on, you know, what is their fiber intake compared to, you know,

typical Western industrialized populations. And I've always wanted to go and actually see the HATTA, see what it's like. And you've obviously done that several times. So, you know, paint a picture for us. You grew up in America, you're on a plane. What is it like? Are you in an urban setting, then suddenly that just sort of stops and Hatsalanda appears? Walk us through that a little bit. Yeah, it is absolutely incredible. You fly into Kilimanjaro Airport, right? And you drive to a little city called Arusha, which is, this is all in northern Tanzania. And the landscape is very, you know, I grew up as a kid in western Pennsylvania here in,

you know, in sort of green forested rolling hills. And I was always, you know, sort of taken by the nature shows and National Geographic that had the savanna, you know, that kind of yellowy grass, the acacia, flat top acacia trees, elephants and zebra and the whole thing. And I was just always, you know, I think a lot of kids feel the same way, which is just seems so amazing and cool. And so you land in Kilimanjaro and you drive out to Arusha and you're driving, you know, you begin to drive into this Savannah landscape and it's just like, wow, you know, you really feel like you've landed in someplace really different, at least from where I grew up. And then Arusha, it's a little city, so you can get all your supplies because everything that you're going to do with, you know, during your work with the HODs, it has to, it's a big camping trip, right? It has to all fit in the back of a Land Rover. And it has to be camping food and you have to get water to bring with you because it's really dry out there.

And you have to get all, you know, all your stuff, not to mention all your permits and everything. It's very heavily regulated as it should be. And so there's lots of regulations for, for doing the science and even just for going out there. And so that's important too. So we get all of our paperwork and we get all of our supplies. And then you drive to another little town called Karatu. And it's smaller. It's half the size of Arusha.

And it's a half day away. And then from there, you kind of do your last pit stops. And then you're out to a little town called Mangola. Right. And so, and there are some Hatha camps around Mangola. If you want it, if people want to go and visit the Hatha, sometimes that's where they go. And then you're, if you're doing, you know, work with the folks who are really hunting and gathering out remotely, you're even further past that more, you know, into sort of just into the space. There's no, there's no villages or anything like that.

You're just sort of driving through acacia trees on a little dirt tracks or something like that. And you just roll up in, in a hot to camp. And so when I say you just roll up in a hot to camp, you need to go with somebody who's been there. Okay. You can't just parachute in. and for us um you know i've been there a few times now but i still whenever i go i go with uh my colleague brian wood who's probably spent more time in a hodza camp than he's spent in his own bed in the past you know more nights in the hodza camp than in his own bed the last 20 years um and uh you up. You can't call ahead. There's no

cell phone service. Actually, some Haaza folks are getting cell phones now because Tanzania is trying very hard to put that part of the country on a cell on a cell network. So, um, it's pretty limited, but some do have a cell phone that sometimes works. Uh, but you can sort of still can't call ahead because it's not, you know, you can't depend on it. And, um, yeah. And, and so the camps are these, you know, maybe it's five, maybe it's 10 grass houses, um, kind of around a nice flat area. They always pick nice places. Um, and, uh, permanent grass houses, these kind of around a nice flat area. They always pick nice places. And permanent grass houses, these kind of semi-permanent structures.

Yeah. I mean, they don't, so they're rooted to the ground, that's a dirt, it's a ground floor. The sticks are about, you know, from, you know, kind of as big as your thumb to a bit bigger. And they bring them up and bring them to the middle.

And then they thatch grass through them. Wow. And yeah, I mean, I don't know how they last a while and then I don't know what the time with it, what the sort of shelf life is on a Hadza house, maybe a year, something like this. I'm just trying to put myself in your shoes and just wonder what is that experience like for an American to rock up to this completely different tribe who's still living, you know, lives relatively untouched by modernity? You know, is there fear? And does that fear then get put at rest? You know, are they skeptical? What are these Westerners doing here trying to

study us and our energy expenditure and our microbiomes? Do you know what I mean? Yeah, no, absolutely. Yeah, I can still remember kind of, you know, the door closing behind you and the Land Rover, you know, and you're walking out and thinking, what was going to happen? And what's funny is they, you know, the Hadza just couldn't be more generous and more gracious and wonderful. And they just kind of come up there smiling. Hey, how's it going? You know, they say, there's the greeting in Hadza, which you learn very quickly because they make going you know what they say they say there's there's the greeting in haza um which you learn very quickly because they make sure you know it you know and you're in your everybody's super friendly and i'm sure it has a lot to do with with uh showing up with brian

because they love brian uh and you know it's not a big community it's only a few hundred people so um brian is i think it's probably met most of them. And they all know Brian and they love him. So, you know, if you show up with Brian, it's like showing up with, you know, with the Pope or something. I don't know. It's like showing up with a rock star. Anyway, yeah, there's that moment of hesitation. And then they're just so friendly and nice that you just, you know, it kind of melts

away. And then you're just amazed, you know, the guys are still walking around carrying bow and arrow, you know, women have just shown up with a, with a digging stick, you know, that they were using just 10 minutes before to dig tubers out of the ground. I mean, it is, it's very, it's, it's, it's so different than anything that I'm used to. And the environment's different. Now I grew up a lot in the woods, so I like that part of it. That's fine with me. The sort of remoteness of it doesn't, that doesn't affect me too much in terms of sort of being a shock, because I've done a lot of sort of, you know, backcountry camping and that kind of stuff. But culturally, it's just so, so different, you know?

Yeah. You know, one of the things that i've enjoyed the most about your book which i've got to say is one of the best science books i've read it's it's so engaging i you know you've got science in it uh you've got hard quality science in it you've got stories in it you've got the evolutionary lens but it's these stories which you know they really they they they lodge into my brain and they don't sort of, they don't sort of leave. And, you know, one of them was, and I think I read this a few months ago when I got an early copy of the book from your publisher. And I think you were there with Brian. I can't remember the chap's name, but I think he'd been unwell with dysentery and some gastro

problems. And then offers you a bit of zebra. So can you tell us a little bit about that story? But also what can we learn from that? Because I thought it was really incredible. Before we get back to this week's episode, I just wanted to let you know that I am doing my very first national UK theatre tour. I am planning a really special evening where I share how you can break free from the habits that are holding you back and make meaningful changes in your life that truly last. It is called the Thrive Tour. Be the architect of your health and happiness.

So many people tell me that health feels really complicated, but it really doesn't need to be. In my live event, I'm going to simplify health, and together we're going to learn the skill of happiness, the secrets to optimal health, how to break free from the habits that are holding you back in your life, and I'm going to teach you how to make changes that actually last. Sound good? you how to make changes that actually last. Sound good? All you have to do is go to drchatterjee.com forward slash tour and I can't wait to see you there. This episode is also brought to you by the Three Question Journal, the journal that I designed and created in partnership with Intelligent Change. Now journaling is something that I've been recommending to my patients for years. It can help improve sleep, lead to better decision making and reduce symptoms

of anxiety and depression. It's also been shown to decrease emotional stress, make it easier to turn new behaviours into long-term habits and improve our relationships. There are of course many different ways to journal and as with most things it's important that you find the method that works best for you. One method that you may want to consider is the one that I outline in the three question journal. In it you will find a really simple and structured way of answering the three most impactful questions I believe that we can all ask ourselves every morning and every evening. Answering these questions will take you less than five minutes, but the practice of answering them regularly will be transformative. Since the journal

was published in January, I have received hundreds of messages from people telling me how much this has helped them and how much more in control of their lives they now feel. Now, if you already have a journal or you don't actually want to buy a journal, that is completely fine. I go through in detail all of the questions within the three-question journal completely free on episode 413 of this podcast. But if you are keen to check it out, all you have to do is go to drchatterjee.com forward slash journal, or click on the link in your podcast app. Yeah, there's, it seems like every day there's, there's a moment like this, if it's, you know, um, a Cobra in camp or, um, or somebody offers you uncooked zebra, uh, you know, anything could happen. So that, that story is fun. So, um, that was forget the year,

I think it was 2015 and we had gotten there to a Hadza camp and it, as it, as it happened, what first or second day that we got there, the guys shot a zebra. And so you're in an intact ecosystem out there. So that's a possibility that people might shoot a zebra. And so they did. And zebras are big. And so we got brought back to camp over people's shoulders and everything else. And then they

slice it up into pieces. They eat all the organs pretty much immediately. And then the meat, which is just lots of meat on a zebra, they slice into sort of thin strips and then they hang it from the trees to let it dry. And so the whole camp smells like a butcher shop for a couple of days, you know, you know, it was sort of three or four, maybe more long, probably more like a week in, people were still eating zebra. And we were going around. One of the things we do is we, we hand out a little GPS units to either where, or sometimes they clip on a belt because we want to know how they're using their landscape. That's one of Brian's big focuses is how they understand them to use the landscape and that kind of traditional knowledge and trying

to understand that because it's, they just, they know so much. Then they see it in such a different way than we do that. It's really just fascinating to see how they look at the landscape, how they use it. So we're, we give out GPS units to wear for the day. And that's, that's fine. And, and we go and find this one guy, Manasi, and he had been just that ill, you know, he'd had. He'd had dysentery or something, who knows, some kind of diarrheal disease, acute infection for a couple of days. And we're like, hey,

how's it going? He's feeling okay. He's like, eh, not really. My stomach still is gross. And last night was bad. And like any other hadza guy at his little camp area he didn't have a family he's by himself so he just has his little sort of cleared area of ground he puts some acacia thorns around the side so no animal walks up on him at night he sleeps on the ground and he's got a little fire smoldering and he's kind of you know pushing it around with his with his fingers and he pulls out a little chunk of zebra meat i realized oh that's he'd been cooking it kind of for breakfast and as we're're talking, you know, he's like, yeah, man, I've been so sick and just gross. And he starts tearing pieces apart. And I think, oh, he's going to, he's going to

eat some breakfast. And he just starts without even stopping, just offers, you know, here's, here's your zebra, you know? And I thought, oh God. The zebra, I didn't mind. But having it handed to you by a guy who just described to you in some graphic detail about how bad his GI tract's been, you know, and not a bottle of Purell in sight. And so you take it and, you know, I look at Brian and Brian looks at me like, well, you know, you don't want to be rude. at Brian and Brian looks at me, we're like, well, you know, you don't want to be rude. So you pop it in your mouth. And it's like, it's like, I think if you, if you'd pulled a piece of chewing gum off the bottom of a table in an elementary school, you know, and, and worked your way through that, I think that's about the texture and the taste of it. But you know, that's how the cuisine and you ask what you can learn from it. Well, first of all, yeah,

you learn how thankful we can all be for modern medicine and antibiotics and vaccines and all that kind of stuff. Because my God, it's a hard life out there. Infectious diseases is, you know, is the number one killer, you know, little kids die all too often out there. It's really that that's, that's not funny at all. It's a sad piece of it. But even adults are sort of dealing with stuff, you know, day's really, that's, that's, that's not funny at all. It's a sad piece of it, but, um, even adults are sort of dealing with stuff, you know, day-to-day, uh, that we deal with a lot less because we have clean food and we have medicine. Um, but the other piece of it is, uh, you know, when people think about what paleo diets look like, yeah, right.

Paleo diet doesn't look like aged grass finished, you know, Angus steaks that you've nicely seasoned and are pairing with your beautiful like asparagus or something like, no. Paleo diets are kind of, most of us wouldn't want to eat a real paleo diet, right? A real hunter gatherer diet, because it's pretty just, you know, it's just functional. Yeah. It's really just, it's just the it's just the it's energy and protein and and it's not like delicious yeah there's a couple of things in that story which really make me think the first is as you say what it what is a true hunter-gatherer diet

and this idea that yeah they they got the the zebra So for a week, that's what they're eating. It's not like this idea. Well, please correct me if I'm wrong here. But this is something I really do feel is that we are seduced these days to thinking that every single meal we eat has to be phenomenally beautiful and tingle our taste buds. And I feel that unintentionally social media and all these gorgeous cookery books actually make this problem worse because you see a breakfast looking absolutely gorgeous, but you don't realize that it actually took five hours to style that. It's probably not even real food. It's probably dried. And the lights had to make it look so great. And so you kind of feel, we sort of feel a lot that each meal has to be like that. And it's something, you know,

even in my own family, I'm very happy having the same thing for breakfast, lunch, and dinner if it's around. Whereas my wife will be, hey babe, we had that for lunch. We had that last time. I'm having that today. And it's really interesting because that is something I'm guessing is not what goes down in real hunter-gatherer land. It's like you don't really have that choice to, you know, whatever you can gather, whatever you can hunt is what you eat, right? Is that how it goes down? Absolutely.

There aren't like breakfast foods and lunch foods and dinner foods in the Hadza camp. It's just food, you know, and breakfast is whatever was left over from last night. I mean, the happiest Hadza kid I think I ever saw, the biggest smile on a face was a kid walking through camp with the skull of a dick dick, a little antelope that his mom, I think, had given him. And it was all boiled out except for the eyeball. There's one boiled eyeball in there. And he had his dad's knife, which was like this huge. And he was, he's like walking through camp, like prying the eyeball out and eating it, you know. And he was so happy. He was like, you know, smiling, everybody look at me, you know, I got the eyeball.

And I think that was the treat. That's your treat, you know. That's, it isn't sort of the sugary breakfast snack. And it isn't the lollipop at the end, you know, and it isn't the cookie. It's, oh, you get the eyeball. Good for you. And, you know, that's, I think the seduction is exactly the right word that we have, you know, we've built these exotic diets for ourselves. And a lot of them are full of really processed foods that we know push us to overeat. But even the well-intentioned foods, I think, can do that. Because if your brain is evolved to eat a diet that's like the Hadza are eating, and now you take that brain and you put it in a world where you get all the delicious food you want all the time, we shouldn't be surprised that our brains push us to overeat a little bit.

And over time, that little bit adds up as a lot of obesity. And of course, it's very hard to overeat these kind of real unprocessed foods, right? Your brain sort of will tell you when you're full. I mean, did you see overeating of any sort that you could tell? Did you observe different sort of body shapes than you might see? Yeah. So one of the things we do when we go to a Hadza camp is we measure everybody's heights and weights. That's kind of a baseline data point that we get for everybody in camp. And so I've measured heights and weights for I think probably a thousand Hadza at this point,

Hadza men and women and kids. And I can remember seeing two women over the course of my 10 years of working there on and off that would be classified, I think, as overweight or maybe class one obese. So two in a thousand. And who knows what their stories were necessarily. They do occasionally like spend some time in the village and then come back.

So I don't know how that obesity or, you know, overwitness developed. I can tell you, I've never seen Hadza women or men sort of doing what I would consider to be overeating. You know, what it looks to my eyes to be overeating. I'll say this. They're not, you know, they consider to be overeating, you know, what looks to my eyes to be overeating. I'll say this, they're not, you know, they're not like scrawny, you know, they're, they're healthy, vital folks. So it isn't like they're starving. And they're always, there's always more food if they want to go get it. They never have the look or this, they never talk about being, you know, starving for food. I mean, they're often, they'll, if

you're, if they come by your camp, so we set up our little research camp kind of outside of theirs to kind of stay out of their hair as much as we can. And if they swing through and we're eating something, then you always share, you have to share. So they're always happy to have a bite of whatever. And so they'll always eat, but they're not starving. They're, you know, they're healthy weight.

And, but yeah, it's really rare to see anybody overweight what what sort of food did you have your own food or would you consume had to food because what's really fascinating is when they do rock by your camp and you offer them something what are you offering them and does it tingle their taste buds in a way that it's like hey you know that's pretty cool i want a bit more of that yeah that's a good question um they we offer them whatever we have and so we always bring, we have to bring your own food. And so unless you've grown up in that environment, you will die if you just try to eat whatever's there. You know, I can't hunt a zebra. I'm not going to do that. Yeah. So, and you can't eat there. So, I mean, if you show up and you're another we're a group of at least four each time because there's me and Brian and a couple of research assistants.

We all know we have we have Hadza actually Hadza who have been in school and and and want to help out as research assistants. We hire Hadza community members to help us with the research, which is really fun. community members to help us with the research, which is really fun. And so, you know, there's four of us at least in our camp and we can't impose on them and say, you know, feed us. They could do it actually, but it would be hard. You know, it's just, we just don't do that. So we, it's like a camping trip for us. We bring all of our food in, you know, in cans or packets or whatever. Yeah. Which means that when they come by, you know, it's, it's maybe it's spaghetti and meat sauce or something like that, or rice and beans. And I mean, it's camping food. It isn't like it's delicious necessarily, but they'll eat whatever. And they're always like,

yeah, thanks. Nice. Check you later. I mean, it isn't, you know, they don't sort of, it doesn't blow their mind. I wouldn't say, but they like it. Yeah, it's fascinating. The other thing I learned from that, or I took from that story about the zebra, is that he shared it with you. Yeah. And you've said that a couple of times in this conversation. You always share.

Yeah. And so, going beyond the central thesis, I think there's a lot we can learn about human nature from your work. And I'm interested, you know, with so much division in the world, so much fighting, that the message I get whenever I read about hunter-gatherers, whenever I, you know, through reading your work, Herman, is that there is, there's a sort of equality and there's kind of, there's that sharing is part of who they are and i guess does that make you think that's kind of who we are as well but we've sort of lost it somewhere absolutely um you know in the discussion about ancestral diets and paleo diets and all this stuff uh there's all this focus on the hunting uh or gathering, right? Are we supposed to eat all animals? Are we supposed to eat all plants?

And what gets completely lost is that it's not hunting or gathering. It's hunting and gathering, right? What do I mean by that? Well, the and part means you're sharing because the and part means that some of us are going to hunt, some of us are going to gather, and we're going to agree to come back at the camp at the end of the day and share. And we are the only primate that shares like this. And we've been doing it for two and a half million years, as long as we've been hunting and gathering. And it's the reason that we're so phenomenally successful as a species, right? Because when we share, we make more energy available for everybody because nobody goes

hungry. We widen the portfolio, broaden the portfolio of foods we can eat. And we also knit our communities together more tightly because we have to depend on this sharing. And the fact that, look, now that we're sort of slowly emerging from all the COVID lockdown stuff, what's the first thing that people want to do? Right? They, you know, they want to go to a pub, and they want to share some chips and their beer, right? And they want to have a barbecue, and they want to have people over and share. I don't know how much how wise

all this is right away. But this is what people are itching to do, right? This is what people have missed is to get together and share food. This is what humans do. Yeah. We're built to do this. And the danger of course, is that we're built to share within our group, right? We don't share indiscriminately across groups. We share within our group. And so what people have manipulated and politicians are very good at this, is deciding who is not your group. And you say, those people are not our group, and they're the ones who are causing the trouble. We're going to be a family. We're a family. We're real.

In the US, it gets talked about, well, the real Americans. Well, who the hell is everybody? We're all Americans, right, If you're here in the U.S. So, but it gets talked about in these kind of divisive ways. And you take this beautiful thing that's really phenomenally important and unique about our species and kind of beautiful, this sharing and communality that we don't have in other species. And you weaponize it because you say, you know, oh, that's only within our group and not across. And then we decide who the other groups are. And you can weaponize that really effectively. And that's the sad piece of it.

How has spending time with the Hadza changed you individually? Yes, there's the science, game-changing science, which I think will have major implications all over the world. But on a personal level, you go back to America with all this experience, having witnessed something that many of us only read about and imagine, but you've been there and seen it. Is there anything that you've put into your life on the back of that? seeing how it's, it's, it's the similarities and the common humanity across these cultures that I think is really, really the most powerful thing to bring home. You go there and we talked about how, you know, you get out of the Land Rover and it's so exotic and different. But the reason I love to go there now is the fact that when I see the Hadza kids running around camp,

I see my own kids, right? When I see a Hadza couple talking about what they're going to do that day or bickering or laughing, I see my friends, you know, talking, my couple's friends talking about their families and what they're going to do. And I see that same commonality, that same humanity throughout all of it. And I think to see the same shape of a life, but in such different terms, it kind of gives you an outside view that you see the whole thing in a kind of an outsider's view. And then you think, oh, wait, what if I did that to myself? What if I could look at my own life from this kind of outsider's view and I could decide what I liked about it, what I'd wanted to change. And I really, it gives you some perspective. Do you really want to work seven days a week?

Or do you want to make sure that you have time for your family? You know, do you want to get three hours of sleep every night? Or do you want to sleep better and exercise more and be healthier in your old age? Do you want to, you know, what's important? And what's important for the Hadza are those personal connections that they nurture throughout a life, because that's who they're with. They're in that social mix every day. There's no, you know, Billy's going to go for the brass ring and check out and work, you know, work himself to death. No, people don't do that. Like, why would you? And so I think that that perspective has been helpful for me to kind of slow down, calm down, nurture the personal connections. That's been useful for me.

Yeah, I love that. Such profound wisdom, Herman, in what you said there. Something I think we can all learn from. Just as we draw this conversation to a close, one thing I really wanted to briefly touch on relating to your work on energy. We're already scratching the surface here. The book has got so much stuff in it that I think frankly, anyone would enjoy reading it really is that compelling a read from start to finish. But there was this bit there where two things relating to that, which is doesn't matter how far you walk or run or how fast you do it, you're going to burn off the same amount of calories. If you run one mile in let's say 15 minutes or you do it, you're going to burn off the same amount of calories. So if you run

one mile in, let's say, 15 minutes or you run it in eight minutes, you're still going to burn off the same amount of calories, which I found, if I've got that right, I found that fascinating. And the other thing was when you compared the different movements and how walking, we're evolved to walk. It's so efficient to walk. We hardly burn off anything running as well. But you said swimming and how costly that can be. So I just wonder if you could just sort of touch on those points just to finish off. Yeah, so this is fun for me

because my earliest graduate student work was on the biomechanics of locomotion. So, you know, the walking, running, climbing, we still do some work like that in my lab. And it's just a really fun game to kind of reverse engineer the body and think about yourself as as this machine moving through space and like any machine we might be interested in how many calories how much energy it burns to go a mile um and you're exactly absolutely right so so running you know the

mechanics of running you're like a pogo stick you're bouncing along and the, the mechanics of running, you're like a pogo stick. You're bouncing along. And just the mechanics of that mean that you're going to end up burning about 100 kilocalories a mile. Depends on how much you weigh, because if you're heavier, then each thud of the pogo stick is more weight, more energy. But so most of us, about 100 kilocalories a mile. Walking, when you walk, you do this amazing thing, which is that you turn your body into a roller coaster track, right? And so you're going up the hills and down the hills and up the hills and down the hills, right? So in a roller coaster, right, it gets you up that first big hill, and then it lets you

go. And then you use the energy from being at the top of that first hill, you use the energy to go all the way through the whole thing into the end. Right, and you need to use the same trick when you walk so as you walk. You kind of don't notice it but as you, your heel hits the ground, and you kind of vault up over your leg. And that's the top of the hill. And then you through the middle, you know, in each step you're doing this rollercoaster thing. And it's so remarkably efficient. Yeah. That you burn about, it's really only like half the calories of running. It's incredible how much energy you save. And we're the only animal that walks with that particular kind of a gate. There are other two legged animals, of course, but we're special

in how remarkably efficient we are. And so that's really fun. But you still move up and down, right? Which is why I'm sitting here drinking my coffee sitting down, so I don't have to have a top. But if you go to your local tea shop or coffee shop and you walk out the door, you got to put the lid on first. Because if you don't, it getsed all over the place, because you're actually on a roller coaster, you don't even know, right? But you're on this roller coaster the whole time. Yeah. And then swimming, well, swimming, we're not evolved to be very good swimmers. And so there's no special bit there. You're just in but instead of, you know, just sort of pushing yourself off of solid ground, now you're dragging yourself through the water. Well, that's that's hard. And so, you know, just sort of pushing yourself off of solid ground, now you're dragging yourself through the water. Well, that's, that's hard. And so, you know,

I don't know off the top of my head with how the numbers compare, but it's a lot more calories to swim, um, a mile than it is to walk or run it. And climbing as well. Is that right? Climbing was more than running and walking as well. Yeah. So that's a really fun one. So climbing, we just published a paper on this. Oh, sorry. We just have it. It's in press. It's not even out yet. It doesn't matter if you're built like a monkey, because people have measured this in monkeys, or if you're built like us or anything, to get your body to climb, let's say 10 meters up a tree, it's the same amount of energy per kilogram of body weight, no matter how you're built. So if you've had a mechanics class, the high school students listening to this

will be familiar with this, which is that if you want to calculate how much work was done, how much potential energy was gained when you go from the ground up to the top of the tree, it really is like a textbook physics problem, which is kind of fun. You take the mass of the thing, which is your body weight, you multiply it by gravity, and you multiply it by the vertical number of meters climbed, and that's how much potential energy in joules that you've climbed. It turns out that all muscle is kind of equally efficient at doing that work and so kind of doesn't matter how you're built and how you do it it's the same calories to go up the top of that tree again whether you're built like me or whether you're built like a monkey or

whether you're built like some other thing you know a lizard or something else that climbs isn't that funny it's one of those like universals of life on earth. Yeah, for sure. There's so much interesting stuff that you talk about or write about, and we barely scratched the surface. Herman, I really appreciate you making time to come on the podcast today. I've really enjoyed speaking to you. The podcast is called Feel Better, Live More. When we feel better in ourselves, we get more out of life. And I wonder if you have on that theme, any sort of closing notes, closing thoughts, perhaps, you know, your research really is profound. It's game changing. You know, have you got any sort of final words of wisdom? You can put it all together so people can start to improve the quality of their lives.

That's a hard question, because I think it's so personalized, right? What you need to do for you is going to be, it's unique to your own situation, but here's what I would suggest. Start by getting outside. I think it's hard to go wrong. Get outside. If you get outside, what are you doing? You're away from your refrigerator, for one thing. You're probably moving. That's another good thing. If you're getting outside with friends, that's even better, right? Fresh air, vitamin D, it's hard to go wrong. People in the industrialized world spend about 90% of their life inside, either inside a house or inside a car. And we aren't evolved to do that. And so, you know, we could talk about the details of a diet or the

details of an exercise program, but a good place to start is to just get outside more. Herman, thanks for joining me on the show. And I hope we get a chance to do it again at some point in the future. Thanks so much for the conversation. It was really fun. Really hope you enjoyed that conversation. As always, please do have a think about one thing or one idea that you can take away from this conversation and start applying into your own life. And of course, do check out Herman's brand new book, Burn, The Misunderstood Science of Metabolism. It is a really, really good read.

Before we finish, I want to let you know about Friday Five. It's my weekly newsletter that contains five short doses of positivity to get you ready for the weekends. I usually include a practical tip for your health. Sometimes I write about a book that I've been reading or an article or video that I found inspiring. Sometimes I share a recipe that I'm making or a quote that has caused me to stop and reflect. Basically anything that I feel would be helpful to share. And it really is so nice to get such wonderful feedback each week from my Friday Five readers. Many of you tell me that it is one of the only weekly emails that you actively look forward to receiving. So if that

sounds like something you would like to receive every Friday, you can sign up for free at drchatagy.com forward slash Friday five. And if you enjoyed listening to the podcast and found the content useful, please do consider sharing it with your friends and family. You could do this on social media, or alternatively, you could just send them a link to this episode right now, along with a personal message. Of course, please also do take a moment to leave a review on whichever podcast platform you listen on. And of course, please do support the sponsors. You can see the full list of discount codes at drchastity.com forward slash sponsors. If you're new to my content, you may be interested to know that I've written

four books that are available to buy all over the world, covering all kinds of different topics like mental health, nutrition, sleep, stress, behavior change, as well as weight loss. In fact, some of the themes we covered today in the conversation with Herman are themes that I have written about in detail in my last book,

Feel Great, Lose Weight. All the books are available as paperbacks, as eBooks, and as audiobooks, which I am narrating. So if that's of interest, please do take a moment to check them out. Thank you so much for listening. I hope you have a wonderful week and please do press follow on whichever podcast platform you listen on. So you'll be notified when my latest conversation comes out. And remember, you are the architect of your own health. Making lifestyle changes always worth it. Because when you feel better, you live more.