Harvard Professor: They’re Lying To You About Running, Breathing & Sitting! - Daniel Lieberman

cancer violence aggression obesity stress if you want to fix all your complex problems well this is controversial but the vast majority of the evidence suggests that Daniel liberman a Harvard Professor who uses the information of our evolutionary past to understand the Health crisis we are in today and educate people on how to live a long healthy life the vast majority of us in the Western World will die from a mismatch disease chronic stress that's what we call a mismatch obesity heart disease many cancers are mismatches and it's because we know live in a world where we're able to have incredible levels of comfort with all this choice for example the number one medical complaint is back pain because I'm sitting in this comfortable chair I don't have to use any of the back muscles so we develop weak backs that don't have any endurance we know that people who sit a lot at work but then also sit a lot in their Leisure Time run way more risk of disease and if you aren't Physically Active you don't grow as much skeleton and then when you hit 25 to 30 for a rest of your life you're going to start losing bone oh even in this highly sanitized World we're much more like ly to develop allergies and various kinds of autoimmune diseases because our immune systems are so unchallenged they end up accidentally attacking us also famous studies show that the Richer the country the higher the rate of cancer Bangladeshi women who mov to England their cancer rates go way up because of diet and physical activity and stress things that have changed in our modern world for which we are very poorly adapted there's a lot to take in is there an actionable conclusion that I can do today that is going to reduce my chances of getting one of these mismatched diseases yes I think there's two the first is quick one this is really really fascinating to me on the back end of our YouTube channel it says that 69.9% of you that watch this channel frequently over the lifetime of this channel haven't yet hit the Subscribe button I just wanted to ask you a favor it helps this channel so much if you choose to just subscribe helps us scale the guest helps us scale the production and it makes the show bigger so if I could ask you for one favor if you've watched this show before and you've enjoyed it and you like this episode that you're currently watching could you please hit the Subscribe button thank you so much much and I will repay that gesture by making sure that everything we do here gets better and better and better and better that is a promise I'm willing to make you do we have a [Music] deal Daniel what is your job title I am a professor of human evolutionary biology at Harvard University and what does that mean it means I get to have a lot of fun um I study uh well my department studies how and why humans are the way we are and we're also interested in how and why that's relevant to to humans today uh my particular specialty is I study the human body I'm interested in how why the human body is the way it is and how that's relevant to health and disease and I most interested most of my work is on the evolution of human physical activity but I'm also interested in in diet and and and other ways in which we use our bodies why does it matter well because we weren't designed you know we weren't engineered neared we evolved right so if you understand why we are the way we are you have to understand that evolutionary history and and if you want to solve problems if you want to deal with you know big issues that we face today obesity you know heart disease cancer violence aggression all of these things have an evolutionary origin and an evolutionary origin is is crucial to to helping us come up with Solutions does what we eat play a role in the sort of starting point of our stories and how began to we I'm thinking about farming Hunter Gathering um and all those things because when I look at human beings versus a lot of animals and you talk about this in the book we Are remarkably fragile in and inadequate in comparison like our eyesight isn't that great we're like super weak I think you say that like most monkeys are stronger than we are squirrels can run faster than us well I think we actually exaggerate our fragileness and weakness to some extent so so chimpanzees our closest relatives um are about probably about 30 30% stronger than we are um you would not want to arm wrestle a chimpanzee right um and most quadrupeds um can run way faster than we can right we are we have this sort of story about human evolution that it's been a sort of Triumph of brains over braa right that we have this we have tools and language and and and that has enabled us to sort of conquer you know the world and become the dominant species and there's some truth to that of course technology uh language communication cooperation all are essential part of the human success story um but you know I think as athletes we're pretty impressive we can outrun most animals over long distances so we're we're really impressive in terms of endurance both men and women we can throw we can kick we can do all kinds of things that my dog can't do as far as diet is concerned you know we're we're the ultimate omnivores we can eat anything um I mean most animals have very kind of constrained diets there are certain things they can eat most of the things out there they cannot eat we've managed to figure out because of of Technology cooking food processing but also because of the nature of our of our digestive system we can eat just about anything on the planet right people can be vegans they can be you know they can eat all meat diets they can you know it's it's astonishing how much variety humans can get by with um our you know our livers can turn anything into anything you can you can we can turn fat into carbohydrates carbohydrates into fat we have an incredibly astonishing range of foods that we can consume when we're thinking about our sort of evolutionary history and and the hunter gatherer tribes that still exist in the world I think I've fallen into the Trap of believing that all the answers we're looking for about how to be healthy humans in the modern world can be found just by looking back at our hunter gatherer ancestors is that true that they hold the answers to how to live a happy healthy life well it's like everything gets complicated right I mean to some extent um we call that a Paleo fantasy this idea that if you just go back to being a hunter gatherer that you'll have no problems right and that Hunter gathers have no violence and they don't get sick and you know all is well well it's not so simple right I'll give you one example murder we have this idea that you know humans have become incredibly violent since the origins of farming right but if you actually look at the ethnographic record Hunter gathers are are just as violent as the rest of us they're they're human beings um they they they they kill for passion they kill for greed they kill for uh you know for that you know there's murder there's there's Warfare among Hunter gatherers even in in some parts of the world yes it's true that hunter gatherers don't have the same problems with obesity they don't have metabolic syndrome they don't have um they probably don't get heart disease least to the extent that we do there are plenty of things that they do that are worth um emulating but but they're not role models in every respect and you know what natural selection cares about is how many offspring we have who survive right that's the only thing natural s cares out it's the equation of life is food in babies out right that's what that's what we're here for right as far as natural selection is concerned not happiness we're not here to be happy we're not here to be nice we're not here to be fulfilled or anything like that although it's good when that happens right we evolved to be hun gathers our ancestors were hun gathers for millions of years but those but the the adaptations they have are primarily and first and foremost about reproductive success so we didn't evolve to eat foods to make us healthy we evolved foods that would increase our reproductive success and we evolve to be healthy only to the extent that Health promotes reproductive success so you you can't just assume that because our ancestors did something it must it's it's optimal for health it's you can it's more reasonable to assume that that's optimal for Reproductive success and remember it's in those environments and in those contexts and things have changed talking there about what they one of the big debates of I guess that's an ongoing debate is whether we are evolved to eat meet or we're meant you know we're meant to be interesting use of words vegan an or vegetarians what's your perspective on that cuz i' I've sat here with people um who are really really passionate about the fact that we're not supposed to evolutionarily see how quickly I tried to say that word because I don't know how to say it um meant to eat meat well that's just nonsense I mean humans have been humans started eating meat about two and a half million years ago there's no question at least two and a half million years ago maybe more and there was no question it played an extremely important role in our evolutionary history even chimpanzees our closest Cousins eat meat occasionally when they can they don't get it very often uh maybe about less than 5% of their diet is meat you know from an evolutionary perspective we evolved to have meat as part of our diet but but of course you can be a human being and not eat meat and do just fine in fact there are some advantages because remember we didn't evolve to be healthy so just because our ancestors ate meat or didn't eat meat doesn't mean that's optimal for health today right it's that's that's very sort of impoverished way of thinking it's just it's just illogical right um You our ancestors didn't evolve to to to read so should we not read reading is only a few thousand years old right so it it doesn't you know that's just not the right way to think about about how to use evolutionary theory and data the the fact of the matter is that we evolved to eat just about everything we are the ultimate omnivores it's astonishing the range of foods that we eat Hunter gather is you know a typical Hunter Gather in in the like for example there's data from the Kalahari I think they eat about uh like 800 different kinds of plants many different kinds of animals right and that's just the Kalahari humans moved over the last you know few hundred thousand years to pretty much every corner of the planet and in every part of the world they found foods to eat humans live in the Arctic where there's almost nothing but meat to eat in many seasons and you know where you you get plant food in the Arctic in the winter by eating the contents of the intestines of of the animals that they they they hunt right um and people evolved to live by by oceans and and and fish and and die for shellfish and you know eat shellfish I mean it's that they live in in in rainforests and eat bugs and you know birds and monkeys I mean everywhere you go on the planet people figured out to eat various kinds of foods and one of the ways we became so omnivorous is that in addition to having incredibly flexible digestive system we also have technology to to Pro process our food so by cooking our food by fermenting our food by grinding cooking cutting it up we've been able to essentially adapt ourselves to an astonishing range of environments hence an astonishing range of foods and so so so now tell me like what diet are we evolved to eat right it's it's an impossible question to answer is there a point in our history where we learn how to hunt and gather and was that the point where we started really eating more Meats yes so well first of all it probably wasn't like a you know a a day you know you know lightning bolt came down from the sky and all of a sudden bam you know so we we figured how to hunt U after all our ape cousins uh will hunt when they can but as soon as we became bipeds which is probably around seven million years ago walk on two feet right we we became slow right you know chimpanzees when they run can Gallop essentially on four legs right and and that and they can be really fast they can't run distances but boy are they amazingly fast and they can climb up trees like like no human can around 7 million years ago when we split from the chimpanzee lineage it looks like we became you know obligatory two-legged bipedal creatures and as when you have only two legs you can only run half as fast as when you can have four legs it's like having a cylinder car with half the number of cylinders right you you know you can just produce less power right and so our early ancestors must have been slow there's no way they could have run that fast fast and certainly not fast enough to be great hunters so I suspect that compared to chimpanzees they were probably poor Hunters because they couldn't run down creatures the way chimpanzees could right so probably for a few million years meat was probably rare in the diet but then we begin to see starting around you know around three million years ago maybe a little bit older stone tools in the archaeological record we find bones with some cut marks on them and starting around you know 2.5 2.6 million years ago we have archaeological sites with with bones of animals with cut marks on them stone tools and those animals were clearly butchered and by 2 million years ago we have clear evidence that humans were were were actually hunting you know we have we have clear evidence that these animals weren't just scavenged they were definitely hunted so that means that sometime between around three and two million years ago hunting became part of our ancestors repertoire they're also making tools they must have been cooperating uh they probably had some form of communication or whatever we don't know exactly what it's like and they're probably eating a wide range of foods including including what we call extractive foraging so they're they're eating tubers underground storage organs right so instead of just plucking berries off plants you know they're they're actually finding high quality foods that you have to dig for right under the ground right it's like just think about a potato it stores its energy underground so there's a these are rich sources of food but you have to be able to dig for them and find them right so this combination of extractive foraging so not just not just plucking leaves or berries off plants but finding high quality resources hunting cooperation tool making and Tool using all together that's the hunter gatherer way of life right and that emerged sometime again between three and two million years ago and that was transformative that's the that's really I think one of the most important shifts that occurred in human evolution and that's also incidentally when we see this shift in our bodies right when we when we going from being more ESS more apik like australopiths which had short legs and long arms and they have small brains and you know they're they're not Apes but they're but they're more apik to basically bodies that are more or less like yours and mine so we have a a fossil called uh the tur boy his real name is naria kame he's from the west side of Lake turana Northern Kenya he's a homus uh who was probably about 8 years old when he died and you know from the neck down he's basically like you and me um his he's his his head is not quite like ours but he's has a big brain not as big as ours he has a doesn't have a snout like a like a like an australopith he's got a vertical face uh he's got teeth that are basically like yours and mine he's basically very you know on that path towards being a human and so hunting and Gathering and the genus homo kind of come together and that was I think one of the most important major shifts that occurred in our Evolution maybe the most important actually more important than even the evolution of our own species and that allowed us to to become good hunter gatherers so we have this nose that sticks out of our face whereas like a lot of our cousins look more like Voldemort like they kind of have the invert and that's a sign that of when we became hunter gatherers right yeah so that external nose right so a chimpanzee has a flat nose like a dog right and that external nose that you and I have which is of course fantastic for holding our glasses right well you don't have glasses not yet at least um uh is um is a oh we think it's a kind of a humidifier so when air goes into our nose it has to go through a little nostril so it's a little what's called a Venturi throat so it it goes through a very narrow um bore and then into a a larger space that has to turn a right angle to get into the inside of our nose and then has to turn another angle to get down into our that pipe we call that the FX that brings air to the down to our lungs and all those twists and turns and and changes in diameter cause the air to be more turbulent so the air instead of flowing in a kind of a you know straight right um become it has these V vortices it's it's got all kinds of currents and when that happens that means that the air has more contact with the the the the mucous membranes in our in our nasal cavity so it can pick up moisture on the way in pick up heat on the way in so our lungs are um don't get dried out and on the way out it can recapture that moisture so that we don't um we don't lose that U moisture when we're um when we're walking or for that matter running so um if you on a really cold day you can do a simple experiment right when it's below freezing if you breathe out right you see all that steam coming out do the same thing breathe out through your nose you'll see a lot less Steam and that's evidence of this this ability of our of our of our noses to trap air um and that's because of this external nose so so that happens around 2 million years ago or so um we can see that cuz on the in the fossils we can see the the margin of the nose and you can see that it's lipped out it's what we call inverted right it sticks out and that's evidence that we had these cartilages that sticked out suuck out and and gave us our modern nose so so if yeah if you went two million years ago and you met an your your ancient ancestors they would have had a nice schn does what does this say about how we breathe today because of there's been a huge conversation I think over the last couple years about breathing and Bre breath exercises and mouth breathing in particular um I've had people on this show like James Nester who talks about how there's a lot of disease happening because we've kind of by habit become mouth breathers when we run um but also so many people seem to be having a lot of problems with their sleep my girlfriend for example she uses nasal strips when she sleeps to try and like open up her Airways and I she think she's going to have to have an operation but we've even got people in our team that are seems like everyone's nose is what do they call it when it's the theid deviated septum deviated septum seems like everyone's struggling with this at the moment yeah I have to say I'm a little skeptical of some of these arguments the idea that you can fix all your health problems by just breathing through your nose um look breathing is obviously very important but um but the idea that for example when you run you should only breathe out through your nose that's just that's just silly um uh that's just not true we evolve to breathe out of our mouth when we run we're the only species that does that actually because it's an way to dump heat when you're running you're generating huge amounts of heat you have to dump it or you're going to overheat um and you you you breathe out through your mouth for that reason right to to kind of um to get the heat out of there right breathing through your nose would be maladaptive and no Elite runner on the planet breathes out through their nose when they're when they're running um I'm not sure where that came from and I just like to see more data to support some of these arguments about nasal breathing I'd like to see data to support the the effectiveness of those of those nasal strips uh sure breathing is important there are better and worse ways to breathe you know we're always looking for Simple Solutions right to complex problems and the idea that somehow fixing your breathing is going to prevent you from having a wide range of diseases is um not true and people who have sleep apnea which is a serious issue um uh that's usually caused by well it's caused by a variety of things of course a deviated septum might be one of them obesity can cause it there's a number of other problems and of course once that occurs um you know again you want to treat the cause not the symptom right so the best way to treat the cause of the apnea is not to put a piece of tape on your nose it's to it's to it's to find the underlying cause by why that's happening in the first place and solve that and deal with that and sweating sort of correlated to that turn in the the fork in the road in our sort of hunter gatherer history because monkeys and even my dog Pablo he doesn't seem to sweat from anywhere other than his mouth I guess it seems like he's his panting is his way exactly exactly so the way in which most animals cool down is by penting right they they breathe uh through their mouth or their nose right and there's there's uh air passes over these mucus membranes on the on the in the nose and the mouth and and and um and what happens is that the air uh by passing that air over the tongue or whatever causes uh you get evapor transpiration so evaporation so the air the the the moisture in that goes from a liquid to a gas phase right and that of course costs energy so because energy is because of conservation of energy that means that for every I think milliliter of oxy of of water that goes that goes from wa water to gas I think it's 561 calories calories of the small CA and that so that causes the tongue or the surface of the nose to cool and then there's blood right behind that blood blood in the tongue thing if you cut your tongue it's really bloody right if you cut your nose right it's a lot of blood there's a huge huge amount of vasculature in there all these arteries and veins right so that you cool then the blood that's just below the surface of the tongue and in the nose and then that cools down your body right so that's so panting is how animals cool or you can even watch a lizard a lizzard also does what's called G pumping it'll it'll actually you know that's how it cools itself down watch a a lizard will run and then it'll it'll basically pent and then it'll run again and it'll pant and it'll run again because it's prevent itself from overheating right now what we did is we've we have uh sweat glands so most animals have there's two kinds of glands right there's one's called aicon glands those are the glands we have in our you know armpits and around our genitals Etc or in our ears they produce waxy sort of fatty substances right there's the ones that smell or or ear wax that protects our ear so all most mammals have those aican glands ecran glands are watery glands and most mammals have them just on their palms their paws and their feet right m so that they can just think about when you wet your finger you can turn a piece of page right it gives you it gives you more grip on something so when you're trying to escape from a predator sweating on your hands will help you run up that tree if you're a mouse or something like that a rodent so most mammals have ecran glands just on their palms but in monkeys uh they started to evolve having some sweat glands on their bodies but not many and so chimpanzees monkeys have some ecran glands on their bodies but what we've done is we've increased that by an order of magnitude we have like 10 times the number uh the 10 times the density of Ean glands the monkeys and chimpanzees and we lost our fur so and of course fur prevents air from from you from convection of air next to the Skin So when you sweat on your skin and you don't have fur the uh you you can have evaporation of of moisture and then and then air takes that away quickly so you can keep evaporating moisture and then you can cool your body so we've effectively turned our entire bodies into a tongue essentially and so we can dump amazing amounts of heat when we're physically active in hot environments and that was obviously important for ancestors uh when they're hunting right we have a huge Advantage In the Heat of the day because we can not only we good at running for All For You know because of our legs and our muscles and Archilles tendon and all these adaptations we have for running but we also have this incredible therm regulatory ability to dump heat which the animal we're chasing does not have and we can we can we can they'll die of heat stroke but we don't know when that happened and it's possible that um that our stopi ancestors before before hunting started because remember they're two-legged creatures right and they're not um they're not very fast so maybe in the middle of the day when when it was really um you know hot that was the best time for them to go out and get food because that's the time of day when carnivores that would love to chase them right if I'm a carnivore and I want to am I going to eat a gazelle or an australopith right aopi is going to be half the speed of the gazelle that's easy pickings right so I'm going to go for an australopith so maybe our early ancestors forged in the middle of the day when it was really hot so that because they because they were too slow to run away from carnivores and maybe that was an adaptation and so the ability to to to dump heat effectively might have been really important for them so it's possible we just don't know that sweating actually came before hunting it's just simply at this point we don't because skin doesn't Preserve in the fossil record we just don't yet know when that happened what about a big brain did that come before hunting or is that a a product of the fact that we started hunting it looks like more the latter right so are chimpanzees have brains you know typical chimpanzee might have about a 400 cubic centimeter brain like 400 grams think about it in grams right typical human has a brain that's like 1,400 gram so you know really like three to four times the size of a chimpanzee's brain for about five million years in our evolutionary history so the earliest hominins hominin is the term for creature more closely related to us than a chimp right so the earliest hominins plus you know these australopiths like Lucy they had brains that got up into the 500 gram range rarely maybe sometimes 600 but not that much starting around two two million years ago brain size just starts to shoot up if you look on a graph right and that's of course around the time we started hunting but it's but it's really the time we have hunting and Gathering and so I think it's the whole system it's it's not just meat although meat must have been an important component of it but the whole hunting and Gathering system is really a way to get more energy right because you're you're you're processing your food so you're getting more energy because you're cooking your food or you're processing it in various ways you're you're cooperating you're you're you're you're you're getting new sources of food such as meat and Marrow and brains and whatever all of that together means that more energy is available and when more energy is available then there's less of a constraint on brain size because brains are expensive just right now you and I we're sitting right we're not really doing much of anything other than talking but one out of every five of our breaths is to pay for our brain our brain is using 20% of our metabolism right and so to have a really big brain means you have to have a lot of energy available to you and so so most animals can't afford big brains because they don't have enough energy right with hunting and Gathering you get more energy more energy means selection can now you know this the con the constraints on having a big brain are now released now you can get selection for a larger brain so individuals with bigger brains might have had some advantage over individuals with smaller brains maybe they were better at doing this that or the other and so you get selection for larger and larger brain sizes and it really acceler Ates up until you know well it continues up until a few hundred thousand years ago when essentially brains reached basically modern size and then you get fat because you have so much energy and you have such a big brain it's it's all about energy but that kind of makes sense doesn't it you store more energy and then we started to get fat well fat is really important for a number of reasons and one of them is having a big brain so um you know a human infant when it's born it's brain is consuming half its metabolic energy like when when a kid is born 50% of the of the of the energy it's spending is just to pay for its brain it's a brain on a little body basically right and um and of course you can't stop feeding a brain brains require energy constantly right brains don't store energy they need a constant supply of glucose or or Ketone bodies which you can use as when you don't have sugar available to you right you can get those from fats right right so infants human infants are born unusually fat guy named Chris kazawa showed that you know we know that a human baby when it's born is about 15% body fat way more than any other species right and that brain that all that fat is really kind of an like money in the bank to make sure that that brain always has energy available to it and furthermore he had published a really cool paper a few years ago which showed that when uh an infant's brain is growing right in the first few years of life the when it's growing really fast that's when its body fat levels are going down and when it's storing a lot of fat that's when its brain isn't growing very much so there's a tradeoff in energy between fat and brains as we're growing so so big brains and fat bodies are intimately connected so we want to make sure our babies are fat a fat baby is an essential fundamental human adaptation and and the body fat that we have I mean a typical human has much more body fat than than than than most most animals most primates have about four or 5% body fat most mammals have about four or five% body fat whereas a skinny human has maybe 10 to 25% body fat right so that body fat is not only important for brains but it's also important for our reproduction because a typical mother nursing for example right uh Hunter gathers will nurse for about three years nursing is really expensive it costs about 600 calories a day to produce breast milk now imagine you're a hunter gather and there's not a lot of food around right you're in what we call negative energy balance you're not getting as much food in as you're spending right you can't just stop nursing you're infant is still going to require that energy so you draw down on your fat reserves right so having all that fat which goes up and down and up and down from season to season you store more fat in the Good Seasons you use that up in the Bad seasons those are fundamental adaptations to keep us Physically Active to enable us to reproduce the way we do to pay for our big brains they're they're part of you know that that you know our our kind of relatively high level of fat and our our predisposition to store fat is fundamental to our species we wouldn't be here if we if we didn't have all that fat and I guess this is why dieting is so hard right because well we never evolved to diet we evolved to put that fat on we did evolve of course to use it when we needed it right but we never evolved um to to to get rid of fat it was just there was never you know in an absence of obesity there wouldn't be selection for for that kind of physiological system to lose fat without needing it because when we try and diet it does feel like our body is somewhat against us when I hear about like sugar cravings and you know many people have told me that if you the reason why diets don't work is because your body's trying to basically defend the weight that you're at because that used to mean your your survival that's right um we call that a starvation response right so when you go into negative energy balance which is what a diet is right you're spending more energy than you're using and you're taking in your body goes into a a starvation response your cortisol levels go up for example right it's a it's a it's an emergency right it's like it's a cortisol is our stress hormone stress doesn't cause cortisol to go up cortisol goes up when we are stressed and it makes energy available to us and one of the things that cortisol does is it makes us hungry right when you're really stressed at night right studying for an exam of one of my students right they get you know hunger you know they get sugar Cravings right because they're cortisol levels because they're stress because I'm going to give them an examine the next day goes up and then they they want energy right cortisol also makes you store fat in visceral deposit so so so belly fat which is which is you know concerning right it's a it's a useful kind of fat right because the fat that we store in and around our abdomen is is very hormone sensitive it's it's got lots of blood vessels so that fat is a great energy Supply when you're you know you're physically active right when I when I want run running around Central Park this morning right I was burning some of my belly fat but when cortisol levels go up that's like it also directs us to B deposit fat in those stores right and the problem with those stores is that um they're also very inflammatory so when those fat cells get too large and they swell they become dysfunctional and they cause inflammation they cause chronic systemic inflammation which is just ruinous for our health it causes diabetes and Alzheimer's and you know heart disease all kinds of diseases that um that pretty much every major disease that we're worried about the mismatch diseases that we often talk about are you know many of them are are stress are inflammation related and and and and that that's why we're con people are concerned about excess uh adiposity excess fat because excess fat causes inflammation so that means that people that are more stressed and more likely to have belly fat correct yes that's true so so that's one of the reasons why stress is you know a risk factor for so many diseases psychosocial stress is a is a it has pernicious effects and that's why you know racism discrimination all those all those factors that can Elevate stress commuting um um have negative Health consequences because it it causes us to our cortisol levels to go up it causes our us to us to put fat in the wrong places it has a cortisol also turns your immune system down cortisol has all kinds of you know negative effects when it's when it's longterm and persistently high it's often been said that if you lose too much weight for example if a woman loses too much weight then her menstrual cycle will stop and I was thinking about this from an evolutionary perspective and you were saying how you know fat is essentially evidence of our survival so in some ways is that our if that is true then is that our body basically sto our menstrual cycle to conserve energy basically if you could think about it like our body saying to us we don't have the energy to have kids right now you are absolutely right so it's a little bit comp more complicated than that but but you you basically got it right so there's two things first of all fat is not just an energy store fat is also an organ right fat fat produces hormones we produce your fat produces a hormone called leptin which affects appetite but it also produces um estrogen so so uh when women have very low levels of body fat their estrogen levels decline um and they don't produce enough estrogen to have effective menstrual cycles um so they become what's called amenic am Menara is is a is a just a fancy medical term for for um U for loss of sort of normal cycling it's been shown by many researchers a former professor of mine Peter Ellison and there other researchers around the world a woman named GNA jensa and Poland others have shown that you know our bodies are Inc incredibly sensitive to energy availability for example women who are dieting they may have plenty of body fat but when they're dieting which means they're going to negative energy balance levels of progesterone which is a very important hormone for the menstrual cycle progesterone is produced in the second half of the menstrual cycle and it maintains the the uterine lining so you can have implantation progesterone levels plummet they go down by you know 50% during the ludal phase that second half of the menstrual cycle um thereby decreasing um their ability to conceive um uh women who are very Physically Active also there's a decrease in the amount of progesterone again during the second half of the menstrual cycle a flip way of thinking about it though is that because remember what we evolved to do is to have as many offspring as possible and so our bodies also another way of thinking about this also is that uh whenever there's extra energy available the body you know it's an adaptation to say hey let's use that energy for reproduction so let's increase estrogen levels let's increase progesterone levels so we can increase our our facundity increase our fertility so there's a bit of a a balancing act yes it's a bit of a balancing act so to so obviously you know exercise is not bad for women who are trying to conceive and and and women who are but women who are sedentary and aren't exercising have high levels of Esten progesterone and that may that's may be one of the reasons why physical activity decreases the risk of breast cancer so much so women who are Physically Active have like a 30 to 50% lower rate of breast cancer and a lot of that part of that has to do with the fact that their hormone levels are more normal because sedentary women have abnormally high levels but nonetheless it's the the important point from what you asked is that our the body is incredibly sensitive to energy right and so it knows that when energy levels are low when you're losing fat this is not a good good time to invest because think about it pregnancy lasts N9 months it's incredibly expensive then you're going to be spending months later nursing which is also very expensive maybe this is not a good time to invest let's wait until times are better then you know that this is a this is a better use of your of your of you know a better time to get pregnant a better you're can have a much more likely positive outcome I was thinking about what you were saying through the lens of stress as well because stress releases cortisol and if someone is incredibly stressed I imagine they're going to have trouble with fertility as well probably for the same reason I guess it's like a line was running at you this is not a good time to have it cortisol cortisol one of the things that cortisol does is it turns down everything that you don't need to do at that moment in time right because we evolve to elevate cortisol acutely you know for short bursts when you know when when the lion comes into the room right um but but not over very very long periods of time so you know when when when the lion comes into the this is not a time to reproduce it's not a time to spend energy on your immune system it's not a time to do all kinds of stuff right just run right make energy available but situations where you have persistently high levels of cortisol chronic stress chronic stress that's what we call a mismatch right mismatches are conditions that um for which our bodies did not evolve right these are novel environmental conditions um for which we are inadequately or imperfectly adapted for and that they cause the vast maj majority of the diseases and problems that we we encounter today and you know taking exams is is a mismatch um having you know you know discrimination racism poverty um these are you know any all those sorts of things that elevate our cortisol levels for long periods of time those are mismatches you know in fact the vast majority of the diseases that people have today um apart from some infectious diseases but the vast majority even of infectious diseases are mismatches because they come from humans spending more time with animals and like all all the a lot of the diseases that we you know infectious diseases that we have actually are diseases that jumped over from the animal world to to humans tuberculosis for example right that's a disease that Hunter gathers didn't get it's a it it came after farming the vast majority of diseases I would say so yeah I mean heart disease I mean look we when we look around the world and look at people who don't live in you know modern Western Lifestyles they they heart diseas is is rare to non existent there's a wonderful study of a of a group of people in the am in Amazon called the chiman there these are horticulturalist foragers right they have there's like no evidence whatsoever of any coronary heart disease in these people some of the populations that we've studied no no increase in blood pressure in fact back in the 1970s some of the first studies that were ever done on the health of Hunter gathers found that 80-year-old hunter gatherers in the Kalahari had the same blood pressure as 20-year-old hunter gatherers in the Kalahari where and they compared them to to to to to English um people and you know londoners at the same time and of course by the time you're 70 or 80 in London almost everybody's hypertensive right this is this is a this is because of diet and physical activity and and probably also stress um these are these are these are things that have changed in our modern world for which we are very poorly adapted no diabetes if it exists nobody's diagnosed it it's probably incred rare but even a few Generations ago diabetes was rare I mean diabetes is the world's fastest growing disease where I work in Kenya um in in the area around the town city called eldoret when I first started working there gosh long time ago you know you drive into the city then you'd be an eldoret now as you drive into the city you pass by all these diabetes clinics they they weren't there before that's because diabetes is rising in in in Africa to at incredibly rapid rates which you know isn't that surprising because diabetes in places like the United States and England are incredibly common about something like 12% of Americans have diabetes now you said that this mismatch is responsible for most diseases doesn't that therefore mean that I'm most likely to die from a mismatch disease in my life yes okay yes the vast majority of us in in the Western World will die from a mismatch disease the number one disease in the world today that kills more people than anybody anything else is is heart disease and as far as we're you know heart diseas is kills at least about a third of us cancer is number two cancers of course are ancient disease so not all cancers are mismatched disease but many cancers are mismatches right breast cancer which is much more common in Western populations than in non-western populations um but heart disease you know is essentially as far as we're concerned non-existent until fairly recently and now it's killing about 33% of us 30 you said a third right yes that's crazy so so crazy that's the bad news right but the good news is because they're mismatch diseases they're not they're not inevitable right we shouldn't just say all right heart disease kills a third of us let's just um because the the amazing thing about heart disease is that diet and exercise can prevent a large percentage if not almost the almost all of them right if people who live in environments where they don't eat obesogenic diets diets that are that make people overweight diets that lead to metabolic syndrome diets that are uh that are atherogenic that cause a atherosclerosis right people who are Physically Active um and stress is also an important role plays a role in heart disease don't smoke um have vastly lower rates of heart disease to the extent that it's you know this is a this is a this is a disease that doesn't have to exist you said you're writing a book about diet and food yes why the story of how the diets that we eat today and and uh is is actually a really fascinating story but also um because I think that we um if we take a more evolutionary approach to diet um we can I think do much better to thinking about you know help people make choices I mean one important point to make is that you know today like when we finish this interview I'm going to go home and my wife and I are going to and my daughter and my mother-in-law are going to try to decide what we're going to have for dinner tonight right and we can like we can go we can eat whatever we want right we can go to the supermarket and there's like you name it right here in New York the really is you name it right we can we can go out to restaurants we can have Chinese or food or Japanese food or American food or French food whatever right we have we have incredible choices to us for most of human evolution history people never chose what they ate ever right they ate what was available to them and now with all this choice we comes comes comes bad choices right and so uh I would like to help people figure out how not only realize that these choices that we have to make are we're not really evolved to do but also how to better understand what those choices are and what the complexities are of of them because there are no there there's no such thing as a free lunch right every every choice that you make has Alternatives and alternative consequences and and I think people oversimplified diet people come up with simple ideas how you know just do this just be a vegan just be a this just be a that um there are no perfect answers do you think in some ways that our culture moved so much faster than our biology in a sense because we're like super sedentary now we just sit all day we have these screens that bring us our food um the food is processed and is this part of what's causing this sort of misalignment all these Mis mismatch diseases as you call them is absolutely because evolution by natural selection occurs really slowly right every generation people with genes that have given them adaptations they're better able to handle a particular environmental context do better than the Next Generation so slowly slowly slowly Generation by generation you get change right and that's true for every animal right um mismatch is not unique to humans right as environments change some animals are better adapted to that environment than other animals and though those animals are going to be more likely to pass those genes onto their offspring so mismatches are part of a natural selection every species as environments change is subject to mismatch or as they move into new environments the difference with humans is that we have culture and culture has caused an acceleration of environmental change right think about I mean just today right I have now a in my pocket a a computer right that I didn't have a few you know decades a AG go right um we have internet and email and all kinds of things right just the last few decades the world has changed amazingly just think about the last few Generations the last few hundred years the last few thousand years so cultural evolution is so powerful and so rapid it's so fast it's so transformative that we have made our world so F vastly and rapidly different that our bodies cannot possibly keep up in terms of our biology it's this mismatch it's this difference between evolutionary biological change and cultural change that has heightened the kinds of mismatches that we exist and then guess what we do right so we let's say we I'll give a very simple example right until recently nobody read right and nobody spent a lot of time indoors and so myopia used to be extremely unusual right what's that myopia is having is being nearsighted okay so if you go to like there's a famous study where they looked in in in Inuit populations right in Alaska and they looked at grandparents and grandchildren the grandparents all had perfect vision and the grandchildren all need glasses or at least a large percentage of like 30% of them right in various parts of the world the the number of people who are are nearsighted has gone up in some parts of the world it's 50% and in America and England it's probably about 30% of us need glasses but this is all recent um the in fact the first study of this was done on the Queen's guards you know the actually now they're the king's guards right so you know those those they have the bare skin hats I don't know what kind of fur it is on their head anyway they're the ones who stand in front of imp Palace right there was a study done in the in the early 1800s which showed that um it was the officers who had a higher percentage like a large number of the officers had to wear glasses but the the the foot soldiers were all fine um and there was something about it right that that about the officers and then people started studying them around the world and and then initially it was thought to be reading and now we know from more careful studies is that's really spending a lot of time indoors when you're young that causes myopia so we never evolved to do that right so we're more prone to myopia but it's not a big deal because guess what we just go to the optician and we get glasses and we can deal with it and you know it's not doesn't really have really any major effect on our on our on our health or our longevity our ability to find a mate Etc we all do just fine can we undo it well here's the thing I mean we're what we're doing in no myopia you you can get lasic surgery and there are some things you can do very expensive most people can't afford it right but the point is that we're treating the symt with when you get glasses you're treating the symptom not the Cause right but it's okay right because it's just glasses right the problem is that for many mismatch diseases right when we are still we're treating the symptoms rather than the causes right so cancer cancer right or or or many forms of heart disease right you don't see a doctor in our in our in our medical system until you get sick right and then you get pills to lower your blood pressure and pills to lower your cholesterol Etc but but these aren't well those some of them can be preventative but but um but to a large extent most of Medical Treatments are treating the symptoms diseases after they occur and I'm of course we should do that we should alleviate pain we should alleviate suffering we should try to decrease people from you know dying from all kinds of diseases but wouldn't it be better if we actually prevented those diseases in the first place right we would have a much more effective medical system so what we're causing in my opinion kind of a new form of evolution I call this dis Evolution where by we're treating the symptoms of mismatch diseases thereby enabling those diseases to remain prevalent right and if some cases get worse because because we can now cope with them right so people now get diabetes we give them metformin or whatever various kinds of drugs they get they get heart disease we give them various you you know pills to kind of keep them going they get myopia we give them glasses all of these are are are are things we should do but wouldn't it be better if we prevented people from getting heart disease in the first place right because this is one of the big questions I always have with Evolution and when we're talking about our evolutionary history is is are we still evolving and from what you said there it sounds like we in a way we are but it doesn't sound good it sounds as you say de Evolution sounds like we're in some ways disolution disolution yeah I mean I mean there is there is a little bit of selection going on I mean you can't stop s it's like gravity it happens but it's slow what we eat and how we eat um I think it was James Nester that said the way we chew impacts what our face looks like when we become adults if a baby's chewing lots of soft foods when they grow up they're going to have like a small jaw yeah that's research I did actually oh really I think you cited you um yeah so so how you your chewing affects the the shape of your you know how your your jaw grows um and so it is true that we have smaller Jaws today than we used to the good news is it's not that bad right doesn't really cause that much you maybe your teeth are more likely to have malocclusions Etc but you know you can but we can go to the orthodontist and have our third MERS extracted Etc I mean we can we can cope with that right it's not um it's that's not the worst thing right of course he thinks that it causes us to breathe through our mouths and all that sort of stuff but it's not the kind of disastrous sort of um mismatch that occurs from say you know uh well this is controversial but um the evidence you know the vast majority of the evidence suggests that if you eat a lot of sugar and you eat a lot of saturated fat you're more likely to get heart disease you're more likely to get plaques in your arteries right if you don't aren't Physically Active you're you know do exercise or or physical activity your your blood vessels start stiffening and you start becoming hypertensive right uh these are all um these are all aspects of our environment that um that we we have the potential to to to control better and to prevent disease do you think we've got into a bit of a bad habit as a society of just throwing a pill at the problem yes I mean that's that's the fundamental argue argument of making about dis Evolution that that you know it's just it's expedient to treat the symptoms of a problem rather than its cause what's the problem with that well because number of reasons one is it's isn't the the best disease is the one that you never get in the first place so so we can keep people alive once they get heart disease we can keep people alive once they get arthritis we can keep people alive once they get all kinds of diseases but they but their but their quality of life goes down and of course we pay for it we pay for it out the nose right it's something like 70 80% of the time when somebody goes into a doctor's office that's for a preventable disease 70 80% of the time right that's a an astonishing amount of money that we spend in our medical system on essentially mismatch diseases it's bankrupting us but it's also causing misery and um it differentially affects people of of low income and people who are of suffer from discrimination um I mean look in the United States right who gets the chance to exercise and eat you know fresh vegetables and you know high quality foods and nonprocessed Foods it's it's wealthy people right so it's also it's just unfair and unjust you mentioned cancer and in what way and how do we know if that's a mismatch disease well cancer is not completely a mismatch disease I mean you know all species that are multicellular get cancer cancer is a is essentially a disease of evolution going wrong right natural selection going wrong right so instead of you know when you have many different kinds of cells in your body when a cell becomes essentially selfish and starts to outcompete other cells because of mutations it gets that's a cancer right so cancer is an outcome of multicellularity and dinosaurs got cancer right we have evidence for bone cancer and dinosaurs um so it's we're never going to get rid of cancer completely but we also know that cancer is very much a disease of energy right when when people move to high energy environments they're much more likely to get cancer more food eating more more food physical inactivity is a major risk factor for cancer um insulin for example high levels of insulin insulin you know promotes um you know anything that promotes mitogenesis you know which is mutation you know cells to divide um um is going to increase rates of cancer um also anything that increases the rate of of U you know a lot of the cells that get cancer are cells in our bodies that interact with the outside world so our lungs our guts you know our colons or you know things from the outside world come into contact with them skin exactly those are cells that often get cancer so when we have carcinus you know poisonous toxic compounds in our environment those can Elevate levels of canc cancer so smoking car pollution etc those can cause cancer but also having lots of energy so we talked earlier about when women are physically inactive their their their hormone levels shoot up right because the body says ha more energy let's spend it on reproduction right and there's a trade-off there more the higher levels of estrogen progesterone increase the rate of of breast cancers that that occur because because they cause more more turnover in those cells in the in breast tissue and that's that's why the those cancer rates are higher so you can there's famous studies which show that you look at women from Bangladesh who live in Bangladesh women from Bangladesh who moov to England or Bangladeshi women who are born in England and live in England wherever you no matter how you how you look at it Bangladeshi women who moved to England their cancer rates go way up the difference a major difference is energy you know the diet that they have the physical activity levels they have they're eating more they put more we cancer rates just shoot up canc so if you actually plot GDP of countries against cancer rates it's almost nearly straight line the Richer the country the higher the rate of cancer what about hunter gatherer women did they have less um ovarian cancer o that's a hard thing to measure because diagnosing cancer requires some sophisticated technology and to my knowledge nobody's ever done careful studies of cancer rates among Hunter gathers um but most of us are pretty convinced that cancer rates are much much much lower among Hunter gathers but again also the the population sizes are tiny so you can't really get very large samples the amount of menstrual cycles you have is major factor right so I believe hope I get the numbers right typical woman today who goes through her entire reproductive lifespan will have something like 500 menstrual cycles because of birth control and um um and smaller families it says 350 to 400 in your book is that what it says okay thank you okay um it's a it's it's in the hundreds right typical Hunter gather is going to have something like 50 50 yeah in her entire life Wow and every time you go through a menstrual cycle your your body is being exposed to high levels of these hormones right birth control um and sort of Modern Family Planning which you know I'm not obviously um opposed to it but it is another factor that has probably elevated rates of breast cancer I didn't I never knew that I never knew that having more Cycles reduced your sure because each every cycle involves you know surges of hormones that's what causes the cycle first you have an estrogen surge then you have a progesterone and an estrogen surge of course that's that's what happens across the menstrual cycle and hunter gatherer women would have been pregnant more often more of their life well yeah they a typical what we call a natural fertility population a population that doesn't use birth control women are most of the time pregnant or nursing and they go through short periods when they um are doing neither and then get pregnant again so so the number of and and you don't of course have menstrual cycles when you're pregnant and you're generally don't have menual Cycles when you're nursing until again it's your energy level so so because nursing costs so much energy that high energy demand of nursing suppresses ovarian function so and so so so nursing women are often amoric they're not cycling and that's not just ovarian cancer that's breast cancer as well that's yeah it's you know you any any any cells that are sensitive to estrogen and progesterone those those are the cancer those those particular kinds of so often when you you you you U measure breast cancer you talk about you know whether the the cells are estrogen or progesterone sensitive I wanted to talk about how our body stores energy because I think that in part uh answers a lot of these questions around around um the things we're discussing about weight loss about diet about all those things we've talked about previously I have a very loose understanding of this so please enlighten me but I did go keto for eight weeks and I lost so much weight it's pretty crazy it bounce straight back of course of course because you're mostly lost water oh really yeah that's one of the problems with many diets so so fat is a is a fat is a wonderful molecule right it's we we tend to demonize it but it's fat is life right fat is a really important molecule so a fat is a is a a fat molecule has a backbone of something called glycerol glycerin right it's a three carbon molecule there's a carbon carbon carbon and there they little hydrogen sticking off and to each one of those carbons is a chain it sticks off a chain what's called a fatty acid so so they're called Tri glycerides they're Three fatty acids on each glycerin and and there are different kinds of fat fatty acids like they're saturated fatty acids and unsaturated fatty acids we can talk about all those whatever but the point is that these are each fatty acid stores a huge amount of energy because those long chains of carbon what our body does is it Cleaves those carbons into smaller units and gets and we get energy from the from the bonds between those carbons that's basically what our mitochondria are doing right so fatty acids fats in general have store a huge amount of energy they store twice as much energy as carbohydrates per unit Mass so what we do is we we eat foods that have fat in them or we eat carbohydrates and our livers convert them quickly to fats it's not it's it's easy right so that's why you know fat-free diets don't prevent people from being fat right often with the help of insulin but it's not the only hormone involved we then we want to store those if you're not burning them right our body can either burn them or store them so if we're not burning them I you we're running or gesticulating talking Etc um um we we're going to store them and we store them in in special cells called adipocytes those are the fat storing cells and our bodies have billions of them you're born with billions of these but you only have so many adipocytes you get them when you're young when you're born and that's it that's the number of adipocytes you have for the rest of your life and so and so those adipocytes so insulin for example helps potentiate the movement of triglycerides right which which you want to break down and then you transport them into the fat cell C and then you reassemble those fats in the fat cell the glycerin and the fatty acids you reassemble them in the fat cell and they swell like a balloon so every little fat cell in your body is like a little balloon filled with with fat and um and it's there to be used and then there are hormones which then help us retrieve that fat when we need it right when we're running a marathon or or just sitting around talking and without having had lunch for a while or whatever um and so you know we we store fat we we then burn fat we store fat we burn fat we store fat we burn fat Etc and that's normal right and as I as we talked about earlier in this conversation humans evolved to have an unusually high level of fat so a typical Hunter gather male will have about 10 to 15% body fat typical Hunter female will have about 15 to 25% body fat that's normal sort of skinny human being that's way more than most mammals right so women had more women have more right so women have a higher uh uh percentage of body fat although actually women tend to be smaller bodied so the total amount of fat that men and women store is about the same women of course if you think about it um because they're involved in they're the ones who have to pay for reproduction directly either during pregnancy or or nursing that fat is especially important for reproduction right so what happens is that that fat is there and it's like a banket count right it's energy that we store and energy that we use and we store it in different places most of the fat that we store stores what we call subcutaneous so underneath the skin subcutaneous but we also store fat that we call ectopic that's outside of where it should be some of that fat is a lot of that that ectopic fat is some of that's in our liver we call that um so people have a lot of so normal livers have just a little bit of fat in them but if you have too much fat in your liver your liver starts to malfunction it's called non-alcoholic fatty liver syndrome you can have fat around your kidneys that's what seid is right but too much fat around your kidneys again causes problems fatter around your heart fatter around so any all that fat in your in your in your abdomen that we call that visceral fat viscera means guts right so that gut fat is is is very problematic and all because when those fat cells get too big so if you store a lot of fat Beyond those sort of normal levels as the fat cells get bigger and bigger and bigger just like any balloon they start to rupture so you know if you overfill a water balloon it's going to break if you overfill an hosy it's also going to start break and when it starts to break it attracts the immune system and the immune system comes in white blood cells come right they're they're they think something's wrong you have a we have we have damage here and they start to produce molecules that trigger a a systemwide immune response right and this and the fat cells themselves also will trigger an immune response the fat cells can produce the same kinds of molecules that are white blood cells produce so the white blood cells are produce molecules called cytokines cyto for cell right Kine for you know enzymes that do something right and and so the ones that fat cells produce we call them adipokines and like one adipokine that produce is called is a TGF Alpha right you may have heard of and that turns on your it's like a it's like turns up the dial on your on your on your inflammatory system right and it goes everywhere in your body and you start getting inflammation right and that inflammation for example if it's those turn if if you have inflammation in your your blood vessels then that inflammation can help cause plaques to form in your arteries if that inflammation occurs in your brain those can cause plaques in your brain that can cause Alzheimer's if that inflammation affects um uh receptor cells on muscles Etc that can cause insulin resistance which can cause diabetes and and the list goes on right so that that chronic inflammation which can be caused by too many fat cells that are overpacked essentially is is why too much fat uh can can be can cause health problems the keto diet and fasting they someone said to me the other day that keto is basically a form of fasting in a way um and are they how do they help the body because people are pretty crazy and pretty keen on both fasting at the moment but also the ketogenic diet well fasting is when you go into negative energy balance right which is how we spent most of our sort of evolutionary history right well you how you spend part of every day right we we eat after you eat you're in positive energy balance and then when you in between meals your energy balance goes down right now you're a neg you're burning now energy that you've stored when you're asleep you're a negative energy balance so fasting is just a prolonged state of negative energy balance right does that mean that it would reduce my chance of getting cancer could do people are are hoping that's the case I don't know how good the data are for intermittent fasting um because if the Surplus and energy causes cancer then me being in that negative energy balance presumably will reduce my chances of getting these right but then you have to go back into positive energy balance at some point too right you can't keep up negative energy balance so intermittent fasting isn't necessarily a way to lose weight if you eventually you know replace those calories right so what you so here's a hypothesis right to which I cannot um I cannot prove but I think that you know when you when you exercise right you're also going to Nega negative energy balance because you're burning energy you're not eating while you're exercise least most people aren't right and and your and your body's turn you know turning on all kinds of mechanisms to to um to cope with that negative en energy balance you're turning on all kinds of repair and maintenance mechanisms when you when you when you're go through intermittent fasting you're basically doing the same thing but less acutely it's it's a more gradual level and I and if you look at the at the at the genes that are turned on by exercise and the genes that are turned on by intermittent fasting many of them are the very much the same and I think it's because you're basically turning on genes that are responding to that negative energy balance um but um but I would argue that you're going to get more of a bang for your buck by exercising than just going through intermittent fasting both well a bit too much yeah I mean intermittent fasting might be a kind of a easy way to get some of the bit bits of exercise without exercising it might be I mean obviously we went we you know there's nothing necessarily wrong with intermittent fasting but I'm not sure that it has some of the huge benefits that people claim now keto diets are a little different right so keto diets are when you're you're basically avoiding any carbohydrates and carbohydrates the the basic building block of most sugars is is glucose right glucose is the sort of a simple form of sugar that are basically in starches there there's some other sugars fructos is also which which is the kind of the sweet one but when you basically stop taking in glucose right you're now basically taking in only fats and and so instead of using glucose to fuel your brain and and other cells in your body You're Now using what's called Ketone bodies these are these are essentially remember we talked about how you when you break those fats down into small little units those are Ketone bodies U they um they can be used as energy but um they're more of a kind of a backup energy source for our bodies than than the primary energy source so we we use them um we T our bodies tend to use them when we don't have glucose available to us and does that mean the same sort of repair and restore mechanism kicks in potentially no I don't think so because that's not negative energy balance you're just using an alternative fuel in this particular point because a lot of doctors have sort of prescribed a keto diet for people that have like epileptic seizures right and I don't think anybody knows I'm not a neurologist but I don't think anybody knows why High Ketone diets are so beneficial for epilepsy but it could be that they do and I just don't know and I'm that's not my it's not my subject but anyway there's a there's a there's a thought that if you just you know essentially keep your insulin levels low and rely on Ketone bodies instead of glucose you can you know do all kinds of miraculous things um for weight loss if you look at the data yes it does tend to uh lead to Rapid short-term weight loss but the data don't s don't show it is very effective as a a long-term weight loss strategy and I think your your example your own anecdotal account is is sort of typical are we too coddled are we cuddling our kids too much and cuddling ourselves too much and is that causing some of these mismatch diseases well I'm not a psychiatrist or a psychologist so uh physically cuddled oh physically cuddled um stopping kids from doing anything that might hurt them or you know the risk aversion and yeah I think so yeah I mean the Comfort industry absolutely I mean you know I have a whole chapter in my book on Comfort right we have this idea that Comfort is somehow good for you like where does that come from right um comfort is nice but you know I mean who wouldn't rather be in business class than in economy right but um but uh is a comfortable shoe better for you right is like is sitting in a chair better for you than walking around or standing is it better to take the stairs or take the lift or the elevator um so Comfort isn't necessarily good for us but when we but we now want to live in a world where we're able to have incredible levels of comfort and um and it's definitely not doing us some good because you know kids need to run around I mean every kid needs a good hour of physical activity a day to build a healthy skeletal system and to you know for for all the other benefits that come from physical activity so preventing our kids from running around and doing physical activity is definitely a problem is there any evidence that our kids are getting sort of physically weaker or physically oh absolutely absolutely I mean we have data in the United States I mean we have this thing called the Presidential Fitness Test right that was started I think maybe it was Kennedy started I can't some president a long time ago so we have decades worth of data and kids today are are are less fit absolutely uh any ask any army recruiter they'll tell you that fewer and fewer Army recruits are are physically fit and able to be what about strong in terms of Bones and our skeletal structures yeah I mean the rates of osteoporosis are going up and and one of the reasons for that is that you know loading our skeleton when we're growing up causes the skeleton to to acrw mass to to grow bone if you don't if you don't exercise right and especially weightbearing forms of exercise you don't grow as much skeleton and then when you hit you know normally people stop adding bone around 25 to 30 right so I don't know how old you are but 31 all right so you're that's it you have no more bone to add in the rest for the rest of your life you're going to start losing bone right but fortunately you look like a reasonably fit person who was very physically active so you probably built up enough bone so having a a high level of bone when you're you're 25 when you're 25 to 30 as you lose bone that's going to protect you from falling below that threshold that's going to give you osteoporosis but if you aren't Physically Active when you're young you have less bone to start with you're still losing lose bone and you're going to be much more likely to fall below that threshold you're much more likely to get osteoporosis and rates of osteoporosis are rising again it's another one of these mismatch diseases that's Rising radically throughout the world exercise also helps prevent uh bone loss because it it it suppresses the cells that that essentially cause our bones to start being resorbed so so it's a it's kind of a double whammy you're not not enough exercise when you're young you have less Peak bone mass not enough exercise when you stay old your bones are going to lose mass at a more rapid rate I was reading in your book that um teen tennis players can become 40% thicker and stronger when they become older because they were using in in the arm that they use yeah so so when you play tennis right the arm that you use which is whacking the ball that's getting more loading than the arm that you simply use to throw the ball in the air so there's an asymmetry so the humorous the upper arm bone of tennis players can be like 40% thicker than the arm that they use to whack a tennis roone just the bone yeah it's it's a beautiful experiment you know natural experiment in a body to show the importance of loading that that loading causes your your your skeleton to respond because our skeletons are like other tissues in our bodies respond to Demand right we match capacity to demand if you don't demand something of a tissue it's not going to grow the capacity because otherwise it's going to be wasting energy right I know that about muscles I knew that that muscles grow and expand but I didn't think my bones I had any say in the development of my bones absolutely yeah loading your bones is is is is is one of the factors that just we talked about it earlier that's why people who eat harder food you know that's less processed grow larger Jaws right our Jaws have shrunk by about six% we showed by about 6% since we started processing all our food because we're just loading our our Jaws L right that's another example is there a consequence to this well so one consequence is increased rates of malocclusion right there's just not enough room for our teeth uh to fit into our Jaws so now we have to go we have to go to the orthodonist to get our wisdom teeth removed because there's not enough space for them because okay so if I if I just get my kid chewing hard food from the jump then he his wisdom teeth will be fine it might be the case yeah so so so the experiment I'd like to see somebody do of course it's unethical right it would be to randomize two groups of kids have one group of kids basically chew really hard resinous gum for like all their childhood right because you're not going to get them to eat like you know unprocessed Hunter gather of food right but Mak we have them chew gum all the time and then compare them to say their twins who don't chew um that much gum and let's see who you know see you know see see how much of an effect it has on their jaw growth puberty puberty um the age in which women go through puberty has changed quite significantly yeah and I couldn't figure out why it's it's energy again right it's always it's about energy remember life is about energy taking an energy and using that to reproduce so so how much energy you have when you're growing up affects the rate at which you grow and the rate and the and your ability to to switch from growth to reproduction so we have data for example from France there's good data from from hundreds of years in France I'm not sure why the French have such good longitudinal data maybe it's because of Napoleonic army or whatever but we can show that you know 200 years ago French girls were tending to go through puberty they would start their menstrual you know they went through what we call menarchy when they start menstruating around the age of 16 today it's around 12 12 and a half right and that's because of more energy we see that in in the area of Kenya where we do field work right that we looking at the same population kenian speaking people and the in the rural areas where you know they have hard lives right they're they're working all day long there's no machines there's no electricity there's not a huge amount of food girls we go through menarchy about 2 years later than in the urban area just you know 50 km away where there's more food there's more energy there's more Coca-Cola there's more whatever um they and we call that the secular Trend right so that girls are maturing earlier they can reproduce because again what does natural selection want you to do wants you to take in energy and use it to reproduce that's what we're adapted for so if you have more energy we're we're evolved to to to do it earlier every time I have these conversations I realized that I'm sat in a chair for a living for sometimes 3 hours at a time today I've been satting this chair for about 7 hours and I go [ __ ] this is not going to be good for me over the long term if I do this podcast for the next 10 years maybe I should just wrap it in here I mean it's been a good run does it does it matter that I'm spending so much time sitting down is there any evidence that this is going to you know have an adverse effect well so the evidence is that um if you so people who sit more um that can be an issue uh there but there's two issues one is that you look at the epidemiological data what really matters is um Leisure Time sitting versus work time sitting so people who have who sit a lot at work but then also sit a lot in their leisure time when they're not at work they're the ones who want run way more risk of disease than people who are just sitting a lot at work so that's one issue right so so I think you're probably okay because I'm I'm I can tell you you know I I know that you're obviously very Physically Active you work out Etc that's that's going to help be very protective but the other issue and I think we talked about my in the previous interview was sitting bout so so how long you sit for a particular period is also very important so we should be getting up every 20 minutes you're going to be interviewing Dave reand in a few days so Dave Rin published one of my favorite papers ever who showed that the hza sit just as much as westerners they sit about 10 hours a day um but they get up all the time every if you're in a hza camp you know there's Babies running around they get up to get the babies they're getting around to tend the fire they're getting up all the time nobody sits for a few hours and just like does what you and I are doing and when you get up you're kind of turning on the metabolism of your body you're turning on your muscles it's like turning on the car engine right you're you're you're kind of Awakening all kinds of metabolic processes and that seems to have a huge amount of benefit so the key is if you're going to sit get up a lot right go get up go go pee make a cup of tea whatever you know interrupt your sitting a lot I'll be right back and of course if you're going to sit at work make sure that you're not spending you know sitting in your car to get to work isn't good and then you go home and you sit on the couch and watch television that's not good um so you know make sure that those non-work periods of time are um don't involve too much sitting is that why we've got so many of these random pains joint pains you know we were talking about you said back pain is the what you say it's the number one medical complaint in the world yeah back pain and that surely is because of the way we've designed our chairs and our lives well part of that is also just back strength so you know I'm sitting in this lovely comfortable chair here and I'm resting my back against it I don't have to use any of the back muscles right so we we de we develop weak backs that don't have any endurance so they're quickly fatigable right so and actually the best predictor of whether somebody gets back pain is how strong their backs are and not just like uh like you know acute strength like from doing you know like one thing it's it's how how how how how much endurance their back muscles have because because just think about it like I don't know you but like every once in a while I get a back pain right I bend over to pick up a pencil or something like that and I think ah it was picking up the pencil right but that's just the straw that literally broke the camel's back right it's it's really the fact that I just it just happened to be the the event that triggered it but it's when my back is weak right that I'm just more likely to do something a little bit weird and then trigger something that causes a spasm right but having um a strong back muscles is the way really to prevent back pain if someone's just heard everything you've said about these mismatch diseases there's a lot to take in you know there's a lot of different mismatch diseases you said that if you're going to die from anything it's basically going to be one of these mismatch diseases is there a conclus conclusion is there an actionable conclusion about something maybe that I can change or do today or is there there a philosophy you can lend me that is going to reduce my chances of getting one of these mismatch diseases just like a broader philosophy towards life yes I well two I think there's two the first is that understanding why we get particular kinds of mismatches helps us make decisions about how to use our bodies right what to eat how to be physically active how to sit I mean all the things we've been talking about result in action items right let's get up more often right let's not eat sugary fatty foods so often right let's you know let's try to avoid psychosocial stress which is you can't just you know wave a magic wand and do that that's a hard one but we think that our life is normal we think it's normal to live the kinds of you know everybody thinks their nor life is normal right we think the foods that we eat are normal the kinds of physical activities that we do are normal the clothes that we wear the shoes that we wear are normal cars cars all of that right and but um from an evolutionary perspective they're not normal that doesn't mean they're not good or or that they're necessarily bad right but but it it gives us a chance to pause and think and ask you know do we have to live with this right or or how can we modify the way we use cars and taxis and shoes and you know we can don't have to get rid of shoes but maybe we'd be better off with more minimal shoes especially for our kids maybe we'd be better off without you know processed foods that are have all the fiber you know removed and all that you know that fat and sugar added and all kinds of other crap right again let's not engage in a Paleo fantasy and pretend that hunter gatherers don't get sick or that you know Hunter gather you know what if eating like a hunter gather will make you you know absolutely healthy that's not the way it works but we have information that we can learn from our evolutionary history that helps us make better decisions so that's point one and point two is that we need to be really aware of this vicious cycle that we've created in our modern world whereby treating the symptoms of these mismatch diseases are actually driving forward the system and making things worse there's a reason that heart disease is going up in the world there's a reason that diabetes is going up in the world there's a reason that myopia is going up in the world right it's because we're we're we're creating novel environments for which our bodies are poorly or inadequately adapted and then instead of preventing those causes we're simply when we can treating the symptoms and and so we're not stopping that you know the the fundamental problem from occurring and and thinking about it that way from a kind of modern sort of cultural evolutionary perspective it's not a form of natural selection it's a kind of cultural evolution that's going on but it's cultural Evolution that's affecting our bodies and thinking about that vicious cycle that we've created can help us stop the viscious cycle as you'll know if you've listened to this podcast before I'm an investor in a company called hu I'm on their board and they sponsor this podcast Daily Greens which is this powder I have in front of me for those of you that can see that gives you some incredible health benefits your energy your concentration your immunity is now available in the UK for the 91 vitamins and minerals you get from it the adaptogens the daily green probiotics that are within this blend and for the last year or so all of you on this podcast that have dm'd me about this product have asked when it will be coming to the UK it's now here if you're someone that wants to get more greens into your diet then I highly recommend giving it a go not only is it good for you but it tastes good win-win the product was so popular in the US that it sold out over and over again and I think that's what's going to happen here in the UK so get your hands on it now just give it a try take a picture tag me DM me let me know what you think of it um because I think it's going to become one of your staple products if you're someone that's looking for a greens product in your life then I really believe that this will probably become your staple as it has become mine thank you so much Daniel I as you were speaking I was just thinking about something we haven't discussed but that is front of mine for me at the moment which is the Cosmetic products that are in my life I spray all this geant on my pores and I put all this these chemicals on me and there's a whole industry that are telling you to rub these creams into your face and all of this stuff and alcohol in your mouth with mouth mouthwash and over the last three months since we last saw each other I have really started to rethink about all these chemicals that I just assumed were all meant to like throw down our mouths up our nose and you know what I'm saying yeah is there anything that you've learned that any advice I need on that stuff just be skeptical skeptical I mean look there's an entire world of people out there who's trying who are trying to sell us stuff right and and if you're particularly like you you're you're you're you're you're clearly interested in how to live your life better right so I think you're especially vulnerable to people with the latest big idea the latest new product because you're you're a Seeker right you're you're looking for this stuff right so you're you they've got you you're in their target right and um you're you're I think more vulnerable so I think being skeptical now it doesn't mean that all products are bad for you but but probably the most of most of them are right or Le they're not going to do much benefit and there could be be unended consequences everything has trade-offs right when you take some mouthwash right and kill the bacteria in your mouth most of the bacteria they're killing probably are useful right your microbiome you have an oral microbiome a lot of that's good for you right um and it may have a short-term benefit of maybe making your breaths feel a little bit better but but it may have a long-term cost I don't know I'm not an expert on the or out anyway because that was one of the things I looked at I thought okay so I've qu alcohol I don't drink anymore but this mouthwash that I'm having is got all this alcohol in and I'm I'm throwing it in my mouth every day which is killing all the um the good bugs in my gut microbiome and also even on our hands we've because of covid we got into this culture of sanitizing all the bugs off our hands and it was quite scary because I I think again through this lens of like what is the more natural way to live and this constant sanitizing of our hands and our children's hands and this fear of bugs my girlfriend comes back from the gym and she rushes into the house and lathers on all this antibiotic CU she's been touching things other people have been touching I you know when I go to the gym I do that too but yes too I yeah but look you've heard of the hygiene hypothesis right this is so we you know you have the same immune system I have the same immune system as our great great great great great grandparents right our immune systems you know we all have these these really amazing immune systems that evolved protect us from all those germs and worms out there right this is something I talk about in the book too now in this highly sanitized world I still have the same immune system but now it's like it's like doesn't have anything to do right the analogy I use it's like it's like a bunch of teenagers hanging out on the corner with nothing to do it's much more likely to get into trouble right and so people who who grow up especially in more sanitized environments with dishwashers without you know pets without animals Etc are much more likely to develop allergies and various kinds of autoimmune diseases because their immune systems are no longer busy defending them from the normal pathogens that are out there in the in in the world that we evolved to live in and now we still have the same immune system and now you know they're like those teenagers on the corner they have nothing to do and they're M that increases the probability that they start to attack us so that's why peanut allergies and various kinds of allergies and milk allergies and what all these allergies are up on the rise because our immune systems are so unchallenged they they they basically end up um accidentally attacking us because they have no pathogens to deal with um that's true true of of a wide range of autoimmune diseases and so uh so so so being Ultra Ultra sterile environments we you know we think it's like the great but actually and during a pandemic you know it's can actually prevent you from getting an infectious disease but but it also has has costs and like it'll be interesting to see like all those kids who were born during the pandemic who who didn't um interact with other kids that much you know Nur nursery school or play school or whatever who are wearing masks all the time wearing you know get getting all those creams you know those antibiotic creams it's you know um stuff they they might be more likely to get autoimmune diseases we'll see as they grow up what happens to them Daniel thank you so much all of your books are absolutely fascinating it's so bloody annoying because I could just talk to you forever they're so brilliant all of the books absolutely brilliant and um I had so many calls after our last conversation which I think has almost got 10 million downloads which is crazy because feels like it was a couple of weeks ago from friends of mine I got a particularly hilarious call from a lady called deina mcco who is uh she's been a TV presenter in the UK she's one of the most famous people on TV in the UK for 25 years and she called me at 7 a.m. right and she calls me at 7: a.m. she go Stephen I've just listened to the podcast with Daniel Ean she I'm running she was and she was like get out of my way she's getting people out of my way and she's running down on the street well I'm very honored thank you um but I had so many phone calls like that and so many conversations like that because of that um conversation and this book is just gosh the story of the human body it is essential reading and as I've heard it's being used in schools and education um institutions so I do hope that you continue to evolve and update the book with new science ASM when it comes um because it's such an important book thank you again for the generosity of giving me your time it's a huge huge honor and I say that uh I don't say that lightly we have a closing tradition on this podcast where the last guest leaves a question for the next guest you know the tradition okay ah the question left for you is for what would you be willing to die today that's a very hard one um I mean obviously you know it's a it's a I think we all think about that occasionally right um I would um if it need be I think for the people I really love and care about right for my my daughter my wife um and I think I would um I would certainly um be willing to risk uh dying you know if it really had an enormous benefit for for humankind it would not be an easy decision to make and I've never been put into that position so it's all theoretical uh I think you wouldn't know the answer until you had to make that decision at the moment would you die for an idea I don't think so but I don't know interesting but ideas can be powerful and important Daniel thank that's a tough one it's really tough and I'm just going to give it away a little bit here but this is what part of what we were discussing with the previous guest that was on the show and he asked me this question he asked me what I would die for and what I die for an idea Etc and and so I said I'd Die For my siblings and my partner my romantic partner for some reason I said I wouldn't die for my parents but I think it's purely because I think it makes more sense for me to reproduce and have all the kids I'm gonna have um and he asked if I would die for an idea and as he left I thought about it more and if you're saying the idea of quality or uh you know these big ideas that would save lots of people's lives from suffering I think there I would die for an idea I he said would you die for your country as well which is an interesting one yeah it depends what the consequence would be if I didn't one can have these thoughts you can think about it in the abstract but it's totally different when the actual when you're actually confronted with with a decision and what I don't know is whether or not what I just said would actually be the case in the moment and that's why when he said would you die for your country I felt like I can't answer that it would be disrespectful for those that that are dying for their my my country right now yeah but people do yeah and people do and I for me to just sit here in this podcasting chair in this hot studio and go yeah of course I would but I'm absolutely not doing that if they hadn't we might not be here today that's true Daniel thank you my pleasure thank you do you need a podcast to listen to next we've discovered that people who liked this episode also tend to absolutely love another recent episode we've done so I've linked that episode in the description deson below I know you'll enjoy [Music] it

Channel: The Diary Of A CEO

Views: 1,526,198

Keywords: The Diary Of A CEO, steven bartlett steve bartlett, podcast, the diary of a CEO podcast, life lessons, CEO

Id: A-8tPmQtYqs

Length: 93min 33sec (5613 seconds)

Published: Mon Jan 29 2024