Why You Shouldn't Stress About Exercise
Today, we interview Professor Dan Lieberman all about why exercise doesn't have to be that stressful or complicated. A look at exercise through the anthropological perspective, and why its normal to not "feel like it" sometimes. Find out the answers to questions like: is sitting actually that bad for you, how much do we need to exercise, is there such a thing as exercising too much, and more.
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Guest
Dan Lieberman is a professor of human evolutionary biology at Harvard University. His research focuses on an evolutionary approach to human physical activity.
Academic Profile | Publications | Book: Exercised: Why Something We Never Evolved to Do is Healthy and Rewarding
The Takeaways
What is the difference between physical activity and exercise?
Physical activity is moving your body, for example climbing the stairs, sweeping the floor, bicycling to work, carrying groceries.
Exercise is a special kind of physical activity that’s discretionary, voluntary physical activity undertaken for the sake of health and fitness.
In the past, we were much more physically active in order to meet our survival needs. In modern times, exercise has become important because we are much less physically active in our daily lives.
Humans have evolved to reserve energy and avoid unnecessary or unrewarding physical activity, especially when food is scarce. Therefore, we shouldn’t judge ourselves for not always loving exercise. .
Is sitting the new smoking? Is your chair out to kill you?
Sitting is natural. Even hunter gatherer tribes sit for an average of 10 hours a day.
The difference in American society is that many people sit to work all day, and then engage in sedentary behavior as leisure time after work, from driving to watching TV.
Americans also stay seated for a longer period of time, on average 40 minutes, while hunter gatherer societies stay seated for an average of 10-15 minutes. Standing up more frequently maintains metabolic health.
Exercise slows the aging process, also called senescence, and makes you less vulnerable to disease.
Even small acts, such as walking to work or taking the stairs, make a big difference in long term health outcomes.
Exercise also helps prevent weight gain or weight regain, as shown in the Boston Police study.
Bottom line: find exercise that is enjoyable for you.
Studies:
How much physical activity do adults need?
Endurance Running and the Evolution of Homo
You Won’t Live Longer by Diet or Exercise Alone, Study Says
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Juna [00:00:01] As you guys may have gathered, Eddie and I agree on most things.
Eddie [00:00:05] Except for whether we should record sitting or standing.
Juna [00:00:09] Yes, fine. Sometimes I get lazy. I may or may not be sitting as we speak and Eddie is standing. So sue me.
Eddie [00:00:15] But if there's one topic we love to talk about even more than almost anything else, it's exercise.
Juna [00:00:22] I'm obsessed with it. Eddie is a physiatrist, which is literally an exercise doctor.
Eddie [00:00:27] So today, before we get into the New Years and people jumping on to the latest gym craze, let's talk about exercise through a whole different lens.
Juna [00:00:36] On today's episode, we are talking about the evolution of exercise, something that we didn't really evolve to do, but something that is so good for us. I'm Juna Gjata.
Eddie [00:00:49] And I'm Dr. Eddie Phillips, associate professor at Harvard Medical School.
Juna [00:00:53] And you're listening to Food, We Need to Talk, the only podcast that is recorded half sitting, half standing at all times. First, let's start with our review shoutout for the week. This review is very short and sweet, but it's one of Eddie's favorites. He specifically asked for this review to be readout.
Eddie [00:01:19] And this is from Bonica82. "OBGYN approved. Amazing podcast. I'm an ob gyn and I recommend it to my patients."
Juna [00:01:30] This is Eddie's dream guys. People recommending the podcast to his patients.
Eddie [00:01:34] Like Bonica 82. Thank you. It is an honor that you're using our podcast to improve your patient's health and well-being. And to all of our listeners, if you find value in what you're listening to, please share it with your friends, your family, and if you have them, your clients and your patients.
Juna [00:01:50] Oh, okay. I like it. And if you want your review read out loud on the show, you can leave us a five star rating and a review. And there's a pretty good chance that we will shout it out and you help other people find the show. And one more thing before we get to the show. We wanted to announce that in January we were having our first ever special series on New Year's resolutions. So we are going to have an episode every single week in January. Guys, weekly. Whoa! Alert on alcohol, caffeine, sugar, and just the act of setting New Year's resolutions. How can you set yourself up for success? So make sure you tune in in January. And now let's get to today's episode. So today we have a very special guest joining us. We are so excited to have Professor Dan Lieberman. Professor Lieberman, do you want to go ahead and just introduce yourself and give your title?
Prof. Dan Lieberman [00:02:42] Okay. My name is Dan Lieberman. I'm a professor of human evolutionary biology at Harvard University.
Juna [00:02:48] We are so excited to have you. And the most exciting thing that I have found in your work was this idea that we did not evolve to exercise. So can you elaborate what you mean by that?
Prof. Dan Lieberman [00:02:59] Well, first of all, the way to understand that statement is to understand the distinction between physical activity and exercise. So physical activity is just moving, right. So, you know, climbing the stairs, sweeping the floor, bicycling to work, walking to work, whatever, carrying groceries, all of that is physical activity. But exercise is a special kind of physical activity. It's discretionary, voluntary physical activity undertaken for the sake of health and fitness. And so until recently, people were very physically active because they had to be physically active in order to survive. They had to hunt, they had to gather, they had to farm. And until recently, for example, people had to carry all the water they used. There was no plumbing. Right. And now we live in a world where physical activity has become much more optional than it used to be. But physical activity is important for health. And so people have to now do this really weird modern behavior, which is exercise. But but in the past, you know, people, although they were very physically active, they were also energy limited. People struggled to get enough energy. And so spending hundreds of calories, doing some unnecessary optional discretionary physical activity just for the sake of health and fitness was actually really a bad idea. Right. So this morning I ran about five miles, which is about about 500 calories. And, you know, when you're stretched for calories and you have barely enough for you and your family to do it, you have to overcome ancient, fundamental, adaptive instincts to avoid unnecessary or unrewarding physical activity. And that's why so many people hate it. So it doesn't mean it's not good for you. It is good for you, especially when you're otherwise inactive. But we need to be compassionate towards people who don't like to do it because they're actually just following their basic instincts.
Eddie [00:04:38] So could we just get some context? Because I think the word recent for a paleoanthropologist might be different than than some of our listeners.
Prof. Dan Lieberman [00:04:46] We're really talking about the post-industrial era. So the last few generations. So a blink of an eye in evolutionary time. So just a hundred years ago, we know that people were much more physically active than they are today. And in many parts of the world, of course, people are still very physically active. It's only in a few, what we call weird countries, Western educated, industrialized, rich and democratic. WEIRD country.
Juna [00:05:09] That is so good.
Prof. Dan Lieberman [00:05:09] Where being physically active it has become essentially optional. So, so much of the planet today, like many of the places where I do work, people are, you know, working really hard. They're very physically active and they're struggling to get enough to eat.
Juna [00:05:23] So I think this relates a lot to something that my dad used to always say. So my parents come from Albania. I was also born there, but I came here when I was five. So I like to think of myself as basically American. And my dad, when I joined a gym, he thought it was like the funniest thing that I was like going into a building to, like, pick heavy things up and put them back down. He was like, You can just come with me to work. Why are you going to the gym? Because he works in construction a lot of the time. So can you talk about like the response you would get from these communities when you would visit them and you would go for a runs in the morning and stuff like that and what they would say to you and you were going on runs?
Prof. Dan Lieberman [00:05:57] Well, they you know, they used to laugh at me. Well, in Kenya, which is where I've done most of my fieldwork, you know, Kenya running is a you know, it's a profession, right. That's a way to make money, especially the part of Kenya where we work. So a lot of young men and women are out there training so that they can win races internationally. So the idea of somebody running isn't all that weird in Kenya. But what is weird is an old white guy like me who's clearly not going to win anything. I'm like, Why are you running in Swahili? There's a word Z, which means an old man. It's a it's a term of respect. It's a very nice term. And people would call me, you know, Z Y Zuma, which means a crazy old man. And in other places I where I've gone for runs of people, they just find it funny, you know, maybe it's because my running gait, too, you know, I don't know.
Eddie [00:06:41] But for for those folks that stop running. So you've got these guys who might be competitive. We might see them coming down Boylston Street first in the Boston Marathon. Yeah. When they stop running, what happens to their health? Do they look like Americans or.
Prof. Dan Lieberman [00:06:57] Yeah, they, you know, some really great former or elite Kenyan athletes who are let's just say they don't look like elite athletes anymore and they make you know, their people are people and biology is biology. And if you stop exercising and also if you get really rich, right. And you you have now access to infinite calories and all that, and you no longer have to work really hard. Many of them are, you know, get overweight.
Juna [00:07:20] So on that topic, I believe, you know, Dr. Herman Pontzer.
Prof. Dan Lieberman [00:07:24] Of course, he was a graduate student of mine.
Juna [00:07:26] Oh, my God.
Prof. Dan Lieberman [00:07:27] And a good friend. And a wonderful.
Juna [00:07:29] Amazing. So we had him on the podcast when we were doing our episode on Metabolism and we were specifically talking about the constrained model of metabolism and how he studied the Hadza tribe. And I think one of the most interesting findings that I read about in your work is how when you study these tribes, I think we have this idea that they're always standing or they're always active, they're always moving, and that's why they're so much healthier than we are. But can you describe your findings on sitting and how much they sit compared to how much we sit and why that's surprising to a lot of people.
Prof. Dan Lieberman [00:07:59] Or I should say that the data on Hadza sitting doesn't come from me. It comes from Herman and Dave Raichlen, who was a postdoc of mine. And so that was their work, not my work, but I'll report, their work, which is that thank you. That the Hadza sit what we call in the is non-ambulatory behavior a.k.a. sitting. They sit on average 10 hours a day, which turns out to be pretty much the average for an American. So the idea that, you know, your chair is out to kill you and sitting is the new smoking. And all that is to me one of those examples of how people get exercised about exercise. Right? We make people we make people confused. We make them feel bad. We make them feel ashamed for doing something utterly natural, which is sitting. Now, the thing about sitting is that if you look at the epidemiological data, so the big sort of population level data on sitting. It turns out that leisure time sitting is really what's mostly associated with poor health. So people who sit at work but then actually do some physical activity in their leisure, which we call now exercise, right? They do fine. It's people who sit all day, but then also sit in the car to get to work. And then they sit at night, you know, watch TV or whatever and and don't get any exercise. That's where the the epidemiological evidence shows that the problems really arise. And and then the other difference is that is how we sit. So, like, right now I'm sitting in a nice comfy chair with a backrest and and, you know, basically, I don't have to move a muscle in my body. But until recently, people sat on the ground, they squatted, they knelt, you know, they did all kinds of other sitting. And those actually, first of all, use a little bit more physical activity. But the other thing is that we tend to sit for very long. And the really the most important thing is that we tend to sit for long, uninterrupted bouts. So the average bout of sitting time for a American is about 40 minutes. But in the places where I work or the hadza, you know, elsewhere, people get up constantly, they sit maybe for about 10 to 15 minutes. That's the average sitting there. And that's important because every time you get up, you're not using a lot of energy, but you're kind of turning the cells of your body on, right? You're using your muscles and that uses up sugar in your bloodstream. It uses up some of the circulating fatty acids, the triglycerides in your bloodstream, and kind of maintains a metabolic health. So so one of the things that really seems to matter a lot is not so much how many hours of the day you sit, but how long those bouts of sitting are. And of course, what you do when you're not sitting.
Eddie [00:10:17] And so where does the standing desk and the treadmills and the bike desks come in? Because we've also had the privilege of interviewing Dr. James Levine, who is all about treadmill desks.
Prof. Dan Lieberman [00:10:29] Yeah, well, he's the guy who said that your chair is out to kill you. That's why. And which I think is an example. I mean, he's done some very important work, but I think that's, again, an example of how to make people exercised about something that is completely normal. I mean, look, my dog spends her day sitting all over the house, right? So there are probably benefits to standing desks and treadmill desks. To my knowledge, nobody has yet published any research on it. But I'll make a bet that most of the people whose standing desks probably also go out and exercise and figure out the difference between their physical activity from exercise and the and the physical activity from the standing desk. It's probably not that huge. So, look, if you want to use a stand, I mean, I have a standing desk. I like it. But it's not let's not call it exercise. It might be marginally better than sitting, but it's you know, nobody got healthy just by using a standing desk.
Eddie [00:11:18] But is that physical inactivity if you're standing?
Prof. Dan Lieberman [00:11:22] Well, I mean, you look you use about seven calories more an hour standing than sitting.
Eddie [00:11:27] Okay?
Prof. Dan Lieberman [00:11:28] That's like the calories in a slice of an a slice of apple. So if you're worried about calories per se, which is not the only reason to be physically active, you're not going to get a lot of exercise by standing by standing desk. There may be some other metabolic benefits. But again, let's not pretend that a standing desk is exercise.
Juna [00:11:46] I am so thrilled because you may not know this, but Eddie has a vendetta to make a stand for all the recordings of this podcast. And we have stood for all of them. But I just want to say I'm always the one that's lazy and like, can we just sit for this one? He's like, no, but anyways, we usually are standing when we record. I had another question about different types of exercise, so I know you're a big runner. Did you inspire the barefoot running trend or am I attributing own imagination?
Prof. Dan Lieberman [00:12:13] I'm afraid that's sort of probably my fault. Yeah.
Juna [00:12:18] Okay. Okay. So you are the person we can blame for all the barefoot runners in the world, I'm just kidding.
Prof. Dan Lieberman [00:12:23] Well, I mean, it's complicated. So I wrote a paper with my colleague Dennis Bramble in 2004. It was on the cover of You're entitled Born to Run. Right. Which we made the argument that humans evolved to run long distances and that was a pretty big hit. That got a lot of attention. And soon thereafter, you know, the question arose very quickly, which is if we evolved to run. 2 million or so years ago. Obviously we were running barefoot. And how do people run without shoes? So we started in my lab studying barefoot runners. And back then it was a very small, very, very unusual community, let's just say that. And then and there were all these people who had the moniker Barefoot. So was Barefoot Ted and Barefoot John and Barefoot, you know, Eddie and whatever. And, and so we invited them to the lab. We started studying them. And then, of course, because I've been working in Africa for many years, we started people there are barefoot and a lot and people run a lot and they run barefoot a lot. So we started setting barefoot runners in Africa and in 2010 published a paper was also on the cover of Nature, on the biomechanics of barefoot running and how it is that you can run without shoes and why it's not a big deal. And the work was popularized by the journalist Chris McDougall, who didn't get all the details right, I have to say, but was very you know, the book is very inspiring, although we were, you know, used lots of caveats, etc., etc.. If you anybody read that, we call it Born to Run Syndrome. People who read that book had this idea that if you suddenly take your shoes off, all of a sudden you'll be able to run a two hour marathon and you'll never have any injuries and your teeth will be whiter. And and, you know, people will like you more and who knows what? And that anybody who wears a shoe is basically a corporate stooge who's, you know, black coffins on their feet. And and so and what I actually believe is that what really matters is how you run. Mm hmm. And what's on your feet is affects how you run, but you can run terribly barefoot and you can run beautifully in hiking boots. And that's probably the most important thing, and that's always been my opinion. And things got kind of out of hand, I'll put it that way, to my astonishment. And it was portrayed as being this controversy, you know, barefoot versus shod. And, you know, why does it have to be one thing or the other? It's a perfect example of the terrible way in which science is treated sometimes like politics and the hyper polarized. It was kind of distressing to watch the whole thing unfold. I just say, you know, that I haven't sometimes enjoy running barefoot, but nine times out of ten, I'm wearing shoes.
Juna [00:14:54] Oh, okay. Well, actually, the thing I was going to ask was, are there different recommendations for different types of exercise? Because like I said, I know your runner. Eddie's a runner. I love going to the gym. And this may be a rumor I heard this may be untrue, but I heard that for longevity, actually, different types of exercise are different. Intensity of exercise have different relationships to longevity. So for high intensity exercise, it has kind of like a U-shaped curve or something, and then another one has a j-shaped curve. Another one is linear.
Prof. Dan Lieberman [00:15:22] Let me stop you right there. Okay. Yes. So first of all, you just made one of the first big mistakes, which is that you tie it to longevity, you know, because the easiest thing to measure is like when somebody died. Right? Right. But longevity isn't everything. We also care about is is morbidity, illness, health. Right. So what physical activity or exercise does? Is it it actually it stresses your body, which turns on repair and maintenance mechanisms, which slows senescence, i.e. the aging process, make you less vulnerable to disease. And that's in turn makes you likely to live longer. But the key thing about exercise is it helps you stay healthy, which in turn can have some effects on longevity. So the biggest benefits are not longevity. They're actually vitality and prevention of disease and so on. So let's let's just get that out of the way.
Eddie [00:16:11] So that's the health span, is that correct?
Prof. Dan Lieberman [00:16:13] That's exactly your health benefits. The average American has a life span of 79 and a health span of 63. So the average American spends 16 years at the end of life with serious morbidities, you know, diabetes, etc., that interfere with their life. And what exercise does is extend your health span and until modern health care. Health span equals lifespan. So that's the first thing. Second is that there is very little evidence that too much exercise is bad for you. Fact, there's basically almost none. So the idea of a U-shaped curve is, is essentially an idea out there. But if you actually look at good quality data, like, for example, there was a recent study in the UK Biobank where they looked at, you know, large numbers of people in England, some of whom did ridiculous amounts of exercise. And there was no effect of that of being at the very end of the extreme. And we're talking like crazy people who are running like 100 miles a week. There was no effect on their lifespan, none. And there's very little evidence that there's much of a morbidity associated with that. Now, there may be some for example, there's some evidence that, you know, really, really extreme intense amounts of physical activity can increase fibrosis in the heart, which will increase your likelihood of something called atrial fibrillation. But but also atrial fibrillation is much more likely to be caused by inactivity. So so that's that's one thing. But what we do know, if you look at any curve of the outcome, the dose response effect of physical activity is that some is better than none. So there's a very quick drop off. So even a small amount of physical activity has enormous health benefits and those benefits quickly start to tail off. And so, you know, once you get to, you know, there's no exact number in it because it depends on your age and your and your gender and your previous activity, history and so on. But once you get to a certain amount of like, you know, maybe an hour a day, I'm just going to make that number up. It's roughly around there. Any more than that, it's going to have no really marginal extra benefit. So you're doing it because you're addicted to it or you enjoy it or whatever. But the key thing is that if you're physically inactive, just a little bit can be incredibly important. So a reasonable number is based on large epidemiological samples, right? That exercising about 20 minutes a day of moderate to vigorous physical activity. So a brisk walk or more will increase your your lifespan at a particular given age. So how much longer are you going to continue to live at that age? By about 30%, which is a pretty big number.
Juna [00:18:29] Wow.
Eddie [00:18:29] And from a public health perspective, that's where the population sits on the sofa and largely inactive.
Prof. Dan Lieberman [00:18:36] Well, I mean, only half of Americans ever exercise at all and only about 20% of Americans even meet those minimum recommendations. So the average American today is about ten times less active than our ancestors from a few generations ago.
Eddie [00:18:52] Wow.
Prof. Dan Lieberman [00:18:52] So and so we pay a huge price in terms of not just mortality, longevity, but also morbidity. And that's and remember, for many people, right, it's not just about how long you live, but the quality of those years that matter. And what really, really is the key benefit of physical activity is it slows senescence and reduces your vulnerability to a wide range of chronic noninfectious diseases that, you know, reduce the quality of your life. Heart disease, diabetes, Alzheimer's. I mean, the list is really, really long and really nothing comes as close to physical activity in terms of those benefits.
Eddie [00:19:26] So if I could share, when you politely said I like to go to the gym, she was actually talking about lifting enormous weights and putting them down. And the.
Juna [00:19:36] Guys.
Eddie [00:19:37] The weights are like they're not.
Prof. Dan Lieberman [00:19:39] Yeah, well, and look, it's also important to say that there's no one ideal kind of physical activity. And we evolved to, you know, we evolved to do all kinds of things. We evolved to walk, to mostly walk. We evolved to carry things. So there's the weights. We evolved occasionally run and do other vigorous things. And if you look at the data from most, if you only do weights and you don't do aerobic physical activity, you run into trouble. Right? Your cardiovascular system really does need cardio exercise, but you get a lot of other metabolic and musculoskeletal benefits from strength training. And so, you know, the standard recommendation and it's a good one is to mix it up. Right. Aerobic physical activity is the bedrock, but adding strength is really important, especially as we age, because one of the biggest problems as people age, this is a condition called sarcopenia. So muscle wasting. And when that happens, you know, become frail and that becomes harder to to do the basic things in life, get out of a chair and use the bathroom and all that sort of stuff. And then that sets in a vicious circle of yet more inactivity. And it's a real pernicious thing. So as you get older, weights become more and more important doing doing it. But you dont have to do huge amounts, just a little bit is fine. And again, something is better than nothing. So if you're physically inactive and you're struggling, you know, just climbing the stairs every day or all of that will yield benefits.
Juna [00:20:54] Okay. Thank you. Because I have had people be like, you shouldn't exercise too much. You shouldn't go to the gym too much because I like the gym a lot. Also, I just want to say for everybody, I ran and I lifted weights at the gym today and I am proud of myself because I really don't like running. But I was like, I know I need to do both. Anyways, so I'm really happy that I don't have to curtail my physical activity. And we are going to continue with our interview with Professor Lieberman right after this break. So we will be right back.
Eddie [00:21:28] And we're back. So this is a question to our listeners. You've been learning from Professor Lieberman, and you might be asking yourself, wow, this makes sense. Like, I think that the treadmill is a torture device. And Professor Lieberman, on our show, we love having brief historical notes. Usually I take the honor, but we'd love to give that honor to you and please tell us. And the brief historical note for today, what was the original derivation of the treadmill?
Prof. Dan Lieberman [00:22:01] Well, yeah, I actually opened my book Exercised with them with the discussion of treadmills, because if you want to think of anything, the apotheosis of modern exercise is the treadmill, this sort of really weird device that's noisy and unpleasant and expensive, and you have to pay to go to a gym or whatever to use it. And and it makes you work really hard and gets you absolutely nowhere. And it turns. And if you think of treadmills for of torture, you're actually right. The sort of modern version of the treadmill was created in the Victorian era to punish prisoners and, you know, debtors, prisons and things like that, to make sure that they didn't enjoy themselves at the government's expense while they were incarcerated. And they weren't exactly the treadmills we use today, they're kind of like slats and they were had to kind of walk on these slats, but. But that turned into the modern treadmill. Yeah. Other kinds of treadmills did exist and Romans had a sort of kind of treadmill-y sort of thing that slaves would have to. Again, slaves, I think, tells you all you need to know how to turn wheels and things like that. But but, you know, the treadmill doesn't have a very, very positive origin.
Juna [00:23:00] I think we can all relate viscerally to the origins of the treadmill. And we all, I think, understand why we feel the way we do on the treadmill. I had a question for you about I've heard you say that you think the discussion of exercise is biased towards Westerners, it's biased towards athletes, towards weight loss. And I thought that was a really interesting idea because I don't think we ever think about that when we hear information about exercise. Could you just discuss what you mean by all of those biases and how you think they damage the message of exercise?
Prof. Dan Lieberman [00:23:30] First of all, many people's conceptions of exercise come from very extreme exercise that you see on TV or read about. Right. And that includes like athletes or the, you know, the idea of worrying about exercising too much. I mean, who exercises too much? Just a tiny, tiny, tiny, tiny fraction of the population. We might see them on TV, but how many people, you know, run ultramarathons? And if you live in certain communities, you know, there might be a lot of people. But these are it's like less than way less than a fraction of 1%. I don't know what the fraction of people who who exercise too much is. So a lot of people, when they you know, when we get our image of what physical activity is like, you know, we watch the Olympics, we watch elite athletes, we read about marathons and all that sort of stuff. Or we know people who I call exorcists, people who brag and nag about about physical activity, you know, people who I think in my book I say, you know, people who will begin a conversation and at dinner like, well, you know, at mile 17, right, you know, the marathon. Now those are really we're pretty annoying people. Right. And and they know that's not normal. It's not normal to stand on one line and run 26.2 miles to another line as fast as possible. That's a really weird, strange, modern thing. So we get this kind of weird idea that you have to swim the English Channel or run run marathons or or lift, you know, huge weights or whatever. And instead, all you have to do is just go dancing or or play soccer with some friends or, you know, whatever. Physical activity doesn't have to be this laborious, unpleasant, stressful, extreme thing. And again, remember that exercise is this sort of modern Western phenomenon and that is actually counter instinctive. And when people struggle to do it, we should recognize that they're not weird. There's nothing wrong with them. They're actually just normal human beings that we placed in a very abnormal kind of world. As far as weight loss is concerned, that is a also important thing because right now two out of three Americans are either overweight or obese. And it's a big issue and people struggle to lose weight. And it's a big debate right now. There are people out there saying that you can't lose weight by exercise, which, by the way, is absolutely not true. It's that, you know, that 150 minutes prescription doesn't help you lose weight. But there's study after study after study, randomized control, gold standard studies which show that physical activity at a sufficient level and it's not a crazy level, does help people lose weight. And furthermore, even more importantly, physical activity is incredibly important for helping people prevent them from gaining weight or regaining weight after after losing weight. So when people diet and lose weight by dieting and alone, they're much more likely to gain weight after the diet. Unless they also include physical activity. The physical activity will not help you lose weight as rapidly as a diet. But it will. But it does is it helps to keep the pounds off after the diet. And so exercise and diet should be complementary for everybody and especially anybody trying to lose weight and keep the weight off. And you don't have to do crazy amounts to get those weight gain prevention benefits of physical activity. Weight loss from physical activity requires very high levels, but preventing weight gain does not.
Juna [00:26:40] Can you talk about the Boston police study? Is that one example of that?
Prof. Dan Lieberman [00:26:44] Yeah. So the Boston police study is one of many studies which have tested this. And they they got a bunch of overweight or obese Boston policemen who were randomized into two groups. One was randomized into a diet only trial, and one was doing diet and exercise. And I it's been a while since I've read the paper. I don't remember the exact caloric deficit they were doing, which was pretty extreme diet. And it was for, I think, eight weeks or 12 weeks. I don't remember exactly. And they lost a lot of weight. Both groups, the ones who exercised, lost a little bit more weight than the ones who just dieted alone. But here's the kicker, which was that the policemen who were on the weight loss plus exercise regime, those who continued to exercise, kept the weight off. Those who stopped exercising their weight went right back up just to pretty much where it was from before the exercise, of course, to the dieters alone who were not exercising again, their weight went right back up. So that's one of a number of studies that shows, you know, it's a nice study because it's a longitudinal study and it's very clear, a study that shows that the importance of of exercise for preventing weight gain or weight regain.
Eddie [00:27:49] So one of the trends that's hitting the fitness world is actually carrying heavy things around, which, as I say it that way, sounds ridiculous. It's called rucking, which is a term I hear at the VA when I take care of my my veterans because they've all been through. But could you share as a paleoanthropologist the hunting and the gathering? And should we be paying more attention to that now?
Prof. Dan Lieberman [00:28:13] Well, let me just preface my play for answer your question, which is, you know, one of the things that I find amusing about the primal fitness movement and the Paleo diet is this idea that hunter gatherers do it. We must we should do it, too. Mm hmm. That's a very depauperate way of thinking about health, because, remember, we didn't evolve to be healthy. We evolved to be healthy. Only to the extent that health promotes reproductive success. And just because hunter gatherers do it doesn't mean it's a good thing for you to do. And there are plenty of things that we do in the modern world that hunter gatherers don't do, which I have no intention of giving up, like like refrigeration and.
Eddie [00:28:47] Brushing my teeth.
Prof. Dan Lieberman [00:28:48] Brushing my teeth, sleeping on a mattress, etc.. So let's not just think that, you know, hunter gatherers doing it must be good for you. That's a that's the naturalistic fallacy. That said, I do think that carrying is important because carrying is is the most natural form of strength, know, resistance, exercise. Right. And and we know that's important. And so so, you know, when when when people go out gathering, they come back carrying their food that they've gathered back to camp. And they're also carrying their babies. And men who are hunting have to carry them whatever they hunted back. As far as time spent, I mean, it's really complicated. And again, it depends on age and gender. So so course men in some but not all societies, for example, Akta women do a lot of hunting. So, you know, varies from society to society. But I don't know the actual times. But I can tell you that that men tend to go out hunting on a regular basis, but not every day. Sometimes they'll rest after a long, hard day of hunting. And it just varies from time to time. But there's no I don't I don't know of any good average data for the amount of time spent hunting, but I can tell you that among people like the Hadza and others, the amount of time they spend engaged in moderate to vigorous physical activity is about 2 to 4 hours a day. Hmm. The rest of the time, they spend either in light physical activity or sitting. Mm hmm.
Juna [00:30:05] That's a cool when you're talking about the, I guess, dangers of extrapolating from what hunter gatherers do. Can you talk about why you think it's important to look at hunter gatherer tribes? Like, what do you think they tell us about our biology that we can't kind of just learn from randomized controlled trials in the lab of just people in the Western world?
Prof. Dan Lieberman [00:30:25] Well, actually, I think you don't actually need to study hunter gatherers to learn about a lot of aspects of health. You know, studies on Westerners can reveal and help us with an enormous amount of information. But when we study people and just, you know, Boston or London or wherever, we're looking at a very tiny slice of humanity and we're not looking at a lot of the variation that exists. So a good example for is recently a lot of really exciting data has come from studies of the Tsimane, which is a horticulturalist group that lives in the Amazon in Bolivia and the Tsimane, you know, because they live in a rainforest that really high infectious disease loads. So they have very high levels of inflammation and we tend to think of inflammation as being bad, bad, bad. But of course there are different kinds of inflammation. And what the Tsiamne tell us is that there are actually some interesting trade offs and then some of the kinds of inflammatory responses they have may actually be traded off with some other kinds of immune responses. Furthermore, it's not associated with the kind of coronary heart disease and atherosclerosis that we see in the West. So you would never get that kind of information from studying just Westerners, right? So you learn that we can learn a lot from from studying diverse populations and looking at diverse diets and physical activity levels and other aspects of health. And here's another example. Every medical student is told that as people get older, their blood pressure goes up like a standard story. Right. It's probably, you know, standard medical school. Right. The first data set I think ever came on, this was a study of the sun hunter gatherers in the Kalahari by two English cardiologist, Treadwell and Hansen, who went out there and took blood pressure data and showed that 80 year old hunter gatherers had the same blood pressure as 20 year old hunter gatherers. There was no increase with age, and that's since been replicated in many, many populations, which we've replicated. And, you know, Herman Pontzer and colleagues have replicated the Hadza and so on. It's been shown over and over and again events of non-Western non industrialized populations. And yet it still comes as a surprise to many people in the medical establishment that it's not a fact of aging, that blood pressure goes up because we we misrepresent the relationship of things that happen as people get older with age being a cause of those factors. And so by studying, it doesn't have to be just hunter gatherers, but by studying people in other kinds of environments, we can learn a lot about many aspects of health and aging and biology and and so on.
Eddie [00:32:49] So as we wrap up, you've mentioned the book Exercised. Could you give us the full title?
Prof. Dan Lieberman [00:32:54] Sure. It's an Exercised: Why Something We Never Evolved to do is Healthy and Rewarding. And it's published gosh, it was published in the midst of the pandemic. 2021, I think, is the published date.
Eddie [00:33:04] Mm hmm. Any final words of advice and inspiration to our listeners?
Prof. Dan Lieberman [00:33:09] Well, don't be exercised about exercise. Don't. Don't let The Exorcist out there, you know, make you feel bad. If you're if you're struggling to be physically active, go find something that's rewarding that you find enjoyable. And and remember, just anything is better than nothing. And don't don't feel like your chair is not out to kill you and and and probably everything, you know, that any doctor will tell you, you probably know yourself. And it's, you know, we've we've taken something very simple and something very basic and we've kind of made it a source of stress. And it doesn't have to be that way. You know, one of the sections of the book is talking about dancing, right? People don't think of dancing as exercise, but every culture in the world has what I call endurance dancing, you know long. You know, people dance for hours, sometimes overnight and many, many, many cultures. And nobody calls it exercise because it's just fun. It's rewarding, right? And so find something that you find rewarding. And for some of us, it's running. Some people hate running. Some people are gym rats. That's fine, whatever, you know. But let's not let the exorcists ruin it for the rest of us.
Juna [00:34:15] Amazing. What a wonderful note to end on. Thank you so much, Professor Lieberman. We will link to his book on our website, foodweneedtotalk.com, as well as the other studies we referenced. You can find us @foodweneedtotalk on Instagram. You can find me @theofficialjuna on Instagram and Juna Gjata on YouTube and Tik Tok you can find. Eddie.
Eddie [00:34:35] I'm going to be running because I like it.
Juna [00:34:37] Okay? You can find Eddie running. You can find me running, too. Even though I don't like it. Food, We Need to Talk is a production of PRX.
Eddie [00:34:47] Our producers are Morgan Flannery and Rebecca Seidel.
Juna [00:34:51] Tommy Bazarian is our mix engineer with production assistance from Isabel Kirby McGowan.
Eddie [00:34:55] Jocelyn Gonzales is executive producer for PRX Productions.
Juna [00:35:00] Food, We Need to Talk was co-created by Carrie Goldberg, George Hicks, Eddie Phillips and me.
Eddie [00:35:05] For any personal health questions, please consult your personal health provider to find out more. Go to foodweneedtotalk.com.
Both [00:35:13] Thanks for listening.
