The Infinite Monkey Cage - Are we what we eat?

Episode Date: June 24, 2023

Brian Cox and Robin Ince examine their own diets and the diet fads of the past to ask what we should actually be eating. They are joined by Dr Chris van Tulleken, Professor Janet Cade and comedian Harry Hill to discuss the nutritional merits, or lack thereof, of everything from sausages to strawberries, and discover whether our obsession with low fat, low sugar or low carb diets have any scientific basis. They discuss our increased dependence on ultra-processed foods and what this means for our health, and whether eating one calorie of a chocolate bar is really the same as eating one calorie of a stick of celery.New episodes are released on Saturdays. If you're in the UK, listen to the full series first on BBC Sounds: bbc.in/3K3JzyF Producer: Adrian Washbourne Executive Producer: Alexandra Feachem

This is the BBC. This podcast is supported by advertising outside the UK. In our new podcast, Nature Answers, rural stories from a changing planet, we are travelling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working.

Learn more by listening to Nature Answers wherever you get your podcasts. This is the first radio ad you can smell. The new Cinnabon Pull-apart only at Wendy's. It's ooey, gooey and just five bucks with a small coffee all day long. Taxes extra at participating Wendy's until May 5th. Terms and conditions apply. BBC Sounds. Music, radio, podcasts.

Hello, we're back for a brand new series. New episodes will be released weekly, but if you're in the UK and can't wait... You can hear it all right now before anywhere else. Isn't that right, Brian Cox? First on BBC Sounds, Robin Ince. That's teamwork, isn't it? It really is, yeah.

Professional. I'm Robin Ince. And I'm Brian Cox, and this is The Infinite Monkey Cave. Today's show is about what you have got in your stomach right now, possibly also in your mouth, and maybe even under your fingernails if you eat your marzipan without due care and attention. Or is that an offence now as well?

Yeah, that's where the culture wars have gone now. They've moved to marzipan. Anyway, so we're not just going to be talking about marzipan, though. We're also going to be talking about spray cheese, cream eggs, Findus crispy pancakes and toast toppers, all of which our younger producer, Caroline, has never heard of. She's never heard even of the company Findus. She is of the bird's-eye generation and beyond.

And so for her, it's been like watching an old episode of I Love the 1970s. I like the boiling bag. Was it the cod in parsley sauce? Not the butter one. Do you remember there was a butter one? This is great radio, isn't it? Today we're asking the question, are we what we eat? How has our diet changed over the centuries?

Is the processed food we eat today really less healthy than it was in our grandparents' time? And what do we really know in a scientific sense about the ideal diet? And is it true, as many scientists believe, that the next stage of evolution will be that our hands become cylindrical so we can reach the bottom of Pringle's tube without having to tilt it up? Anyway, today we're joined by a twin with an interest in infectious diseases, a professor with an interest in nutritional epidemiology, and someone who changed from being a doctor to a cake commentator.

And they are. I'm Dr Chris Van Telleken. I'm an associate professor at UCL next door. Like most sort of media doctors, I have eventually gravitated toward nutrition. I've written this book, Ultra Processed People. And my favourite guilty food pleasure is scotch egg, but the one with the black pudding.

Ooh. Can I just check? No one knows. it's not exotic can i just check when you say you study at ucl next door do you mean at ucl which is near here or do you mean you're in a kind of tribute university called ucl next door do i have to answer that question? No, we'll move on. Hello, yes, I'm Janet Cade. I'm Professor of Nutritional Epidemiology and Public Health at the University of Leeds. And my guilty food pleasure...

Well, you already mentioned marzipan. I didn't know it was a thing, but I like chocolate, and particularly chocolate-coated marzipan, or those chocolate-coated cherries soaked in kirsch that you get at Christmas time. Yeah, they're nice, aren't they? Follow that, Harry, because they're done very well on that side. Yes.

I am Harry Hill and I am also Professor of Nutritional Epidemiology in Leeds. No, of course not. I am a comedian. And my favourite guiltiest food pleasure is sausages and this is our panel looks like you lost your bet there brian none of them said cannibalism anyway let's move on janet we're bombarded with advice about about food it's everywhere but in in a scientific sense so just strictly scientifically speaking how much do we know about what constitutes a good diet we know quite a lot there've been lots of studies over many years long term large scale cohort

studies where we can measure what people have eaten in the past, what diseases they get in the future. And so we know things like we now have government eat well guide. It used to be a plate. Somehow it's come off the plate. It's now a guide, which tells us that we should have probably majority of our food, fruit and vegetables, about 40% fruit and veg, maybe similar amounts of potatoes and cereals and rice, smaller amounts of protein, but less sugary things,

which fruits can be quite sugary, but not dried fruits, not too much oil, not too much salty stuff. And if a pudding? Yeah. Yeah. Chocolate. No, no no no don't you think those chocolate cherries could be part of your five a day or or or not maybe not you're the one with the answer you've been peer-reviewed in the past whatever you say this audience will accept it yeah well they're not let them live the good oh sorry yeah no well i could have couldn't i but they're not really actually it's still all about balance not too much enough micronutrients

all those vitamins and minerals and enough hydration as well it sounds kind of obvious and boring though it's difficult to do because obviously, you know, our needs change throughout the life course. So actually to define what is a healthy diet is quite challenging. Are you saying, as professor of nutritional epidemiology, that a little of what you fancy does you good? I don't want to put words in your mouth, Jack. That is broadly speaking. So it's essentially in moderation. You listed virtually everything. Everything.

Everything. Yeah. In moderation. I think so. I think that's the answer, isn't it? What we've done is we've swamped ourselves with high energy density food products that we want to eat more and more of.

So it's about having that restraint, perhaps, moderation, making sure we have enough fibre in our diets, because I think that's one thing that we're all quite short of. We need to eat more dietary fibre. By doing that, you reduce your energy density, so you're eating less calories and not gaining that weight that you might do otherwise chris now for a lot of people that they they know you you're both for operation out and also for you know an area of expertise is infectious diseases but you are now increasingly

as you mentioned as well the book that you've written etc you're you're fascinated in nutrition what when did that start when did you become that interested in nutrition so i came there through an odd route because I'm an infectious diseases doctor. I've done a lot of global health where I've worked in very low income countries. And we see that the malnutrition caused by the food industry, marketing foods, harmful foods very aggressively to people who don't have clean water, who don't have the capacity to store them or make them up properly, causes malnutrition that leads to infections. So working in countries where people don't have enough money creates an interest in the food that supports our immune system

and supports our health. So that's the background to how an infectious diseases doctor comes to be interested. I was interested as well because there's a big exhibition at the moment in London at the Wellcome Collection all about milk and it seems like the story hasn't changed in a very long time because there was a big poster and it was all about how condensed milk was something which people in poverty were often using as an alternative to breast milk and that was creating malnutrition and from you know reading some of books, that seems to be still the issue 80 years on.

Infant food is a really ticklish thing to talk about because it's incredibly stigmatised because everyone feels very wed to how they fed their children. And we feed our children according to the food that's available in the society we live in. We have really an emergency about child health particularly, where one in five children have a leaving primary school with obesity. And it's nothing to do with their fault. These are diseases caused by an industry that is aggressively marketing foods that, as Janet says, are really, really hard to stop eating

and that interfere with our evolved mechanisms that tell us we've had enough. See, I was going to talk about junior bake-off, but I don't know how to say that. Oh, I think there's a very easy segue here. I think it's very simple, which is, Harry, we've just been talking about children and too much sugar. You force children to eat cakes on television, don't you? Do you feel like maybe you're the bad man?

Listen, if they die, they die. They know... They know what they're getting into when they join up it's true though i mean as a kid when i was at school when i was like in the 70s every school just was allowed one obese kid wasn't there there was one fat kid he was called donut and he had a briefcase full of crisps i mean and his mum claimed it was a glandular problem, but now they're everywhere.

And this is the subject of today's show. I mean, the attitude to food has changed. Like I say, when I was a kid, you wouldn't think to take a photograph of your lunch and put it on, you know, and show it to someone because basically food was so horrible back then you wanted to forget about it. And the other thought I had about your...

You were saying about what's a good food and a bad food. Surely, yeah, OK, great, eat a lot of blueberries, but, you know, if they're out of season, then they're being flown in from, I don't know, somewhere, and that's bad for the environment. You know, it goes beyond what you're eating, surely, doesn't it? Yeah, I mean, we definitely need to consider not only nutritional aspects, but sustainability metrics too.

So, I mean, who knows how bad for the environment our diet is at the moment we're still finding that sort of thing out because everyone always talks about the mediterranean diet being good for you but you know if you live in the mediterranean you can eat that stuff but over here you but you don't fly in even now you know mediterranean diets changed over the last 50 years or so so what what's been talked of as a Mediterranean diet, plant-based, small amounts of good quality red meat, a bit of red wine, olive oil, and so on,

people living in the Mediterranean now aren't eating diets like that anymore, which were the things that were helping people to perhaps live a bit longer. So, yeah. That idea of the Mediterranean diet, as you mentioned, it's 50 years years ago there was a specific diet the first question I asked was about the evidence what we know wasn't that historically one of the first big studies about nutrition yes

there have been early days I suppose was Mediterranean diet and that linked through to low-fat diets as well but some of that I think links to the industry perspective and the low-fat diet then that followed on from the Mediterranean diet was really being promoted by American senators who maybe had a family history of heart disease and even before all of that if I could take you back in time to the Boer War I had to look up that actually how to pronounce Boer. I thought it was Boer War. The Boer War was a battle between strippers and drag acts. So what am I saying? Boer War. The Boer War. So the Boer War was actually, I think, the birth of nutrition as we know it today. And it came about because the conscripts going to war were malnourished.

And so everyone was very worried about that. The medical fraternity were a bit up in arms and published something in the British Medical Journal, which in 1903 said, if parents' earnings were insufficient to provide an adequate diet, it was easily conceivable that the British race would deteriorate.

Now, whilst I don't like the idea of British race, but nevertheless, we could be hearing those words today, couldn't we? If parents' earnings were insufficient to provide an adequate diet, you know, children are going to be malnourished. That's what you were saying, Chris. And this is profoundly true in 21st century Britain, in 2023,

that if you are in the lowest 10% of households by income, you would have to spend almost all your money to eat, according to the NHS guidance, to eat a healthy diet. So you wouldn't have any money left for your rent, for your energy, for your fuel. So this sort of food apartheid that we live in is a huge problem where people simply don't have enough money to eat well so this is it's interesting to me because a lot of the way this can get talked about is oh it's because people eat junk food it's because people but if we're talking about 100 years ago we're talking about you know we've been talking

about 200 this seems to be again it's it's perhaps the contents of the story change but the story itself doesn't seem to change i think there is a there is a sort of national understanding that people have a personal responsibility for what they eat and there's a lack of understanding that actually we just eat the food that we can afford and it's presented to us. And at the moment, we're surrounded by food that's extremely hard to stop eating, and much of it is sold to us as food that's healthy. So we have this classification now of ultra-processed food, which now makes up more than half of our diet. It's about 60% of what we eat.

And there's a long formal scientific definition, but it boils down to food that's wrapped in plastic and it contains an ingredient you don't find in your kitchen so just going to processed food first of all so processed food what would that be for people today brian today had a chicken curry pie for his lunch and uh that's true it's what he had it was the only pie left he was quite cross about it it was either that or a vegan pie and he won't eat anything unless something's been killed. He has no emotion or heart. Are you his carer?

You just had that look about him. What would be a processed food then? Well, if we think about milk, milk's quite a good example. If it's whole milk, you can drink it straight out of the cow. It's just a whole food. We can process it and turn it into traditional foods cheese butter and we've been making cheese and butter for six seven thousand years we don't think those foods are associated with diet related disease we don't think they cause early death or we can ultra process it

where we can we can separate the milk into its fats and use them for something else and then we can make low-fat yogurts with modified maize starches and artificial flavourings and artificial sweeteners. And those foods have been ultra-processed, and we think that that category of food is associated with weight gain, partly because they are engineered to drive excess consumption. I mean, that is the purpose of most of the packaged foods that we eat today. And they're not hard to stop eating by accident.

They're hard to stop eating because they're meant to be hard to stop eating. Janet, I mean, that sounds quite kind of Machiavellian. But is it specifically designed like that? Or is it more, hang on a minute, this is selling really well, let's make more of this. So it's not quite as pre-planned as it might look. I don't know about pre-planned. But what I do know is that those foods tend to be very energy dense and they're easy to eat and you eat them more quickly

than if you were having to choose something which had a lot of fibre in it. So you're going to eat more of it. So whilst the processing may be an element, it may not be an element. It may just be what's in the food, the nutrients. So too much energy. You're eating it quickly. It's soft and pappy.

It's easy to just shovel in and keep shoveling in. It tastes nice. Taste must play some role in this. Taste does. You know, taste is a whole other interesting area. Babies, when they're born, one of the first things they do like is that sweet taste. They're drawn to that and will eat sweet foods.

So we're kind of programmed for that. Janet, when did you, I mean, you're involved in a panel looking at the toxicity of food. So I would imagine in the 16th century, you would have just been someone who walked through woods and told people not to eat those berries. That's your view of a professor of nutrition. you would have just been someone who walked through woods and told people not to eat those berries. Whereas now... That's your view of a professor of nutrition. To be honest, science in the 16th century was not great, Brian, OK? You've seen that wig that Isaac Newton wore? That's not an intelligent man's wig.

Can I give you a story about the first controlled trial? Actually, nutrition has a great history in that the very first controlled trial was of foods and nutrients. A Captain James Lind in 1747 noticed that all the sailors on long haul journeys were dying and dying of scurvy they didn't know what was causing that as we know today it's lack of vitamin c and so he allocated different groups of sailors to receive different things some had to eat seawater others various things including some with the sort of citrus fruits and they were the ones that survived so actually whilst you might say you know someone wandering along saying don't eat this do eat that that's kind of how it happened you could have had cider or nutmeg as well they were two other options cider or nutmeg yeah it was a various

different i'm not sure obviously it was before my time actually yeah so that's when we begin to see nutrition as i suppose as a science. We were driven to it by the necessity to keep people alive on long sea voyages, essentially. And how does the science then develop? I mean, today, as you said in the introduction, it's complex. And understanding what an ideal diet is is a very complex question. So what are the landmarks if we go through the history of nutritional science?

So when I grew up, for example, people would, I remember it vividly, it was don't eat saturated fat. There was, it was certainly in the 70s and 80s, saturated fat is an evil thing and do not eat it. But now that seems to have changed somewhat and saturated fats are not the demon that they were made out to be. That's right, they're not.

The evidence wasn't there for saturated fat when they actually looked and did some randomised control trials testing saturated fat versus other types of fat or lower fat, and they just didn't find the evidence that that was associated with increased risk of heart disease. So, yeah. Is it OK to eat butter and cream then? Yes.

Oh, no. Yeah! All these lost years. I remember thinking at the time, everyone was eating margarine in the 70s, wasn't it? I remember finding out how it was made. It's like sunflower oil passed over i think it was an aluminium catalyst and i thought how can that be good for you yeah because it was

it was a unsaturated high in unsaturated fats wasn't it was a marketing very much so yeah which i remember and then it obviously was followed with things like the atkins diet the um very low carbohydrate diet to treat obesity. But actually, again, that's been, I would say, discredited. It's neither low-fat nor low-carbohydrate. It is the simple message about how much energy. And then if we think about physical activity levels, that's gone down. So actually, overall, our energy intake needs to come down so by energy you just

mean it's what you read as calories calories exactly i do yeah yeah it doesn't matter where it's coming from it's total calories which is interesting isn't it because because today we hear lots of messages about this this is this food is good for you this food is bad for you this don't eat as many carbohydrates or whatever it is because it turns into sugar and but but essentially you're saying the bottom line first and foremost is how many calories are you ingesting per day relative to how much you and conservation of energy basically and whilst i'm it's being marketed at us even so i suppose i'm interested in measuring that you know which of us here knows how many calories we've consumed already today? I don't.

So unless we try and get a handle on that and measure that, not every day I'm not suggesting, I've got a theory I would like it to become as common for us as children to kind of take a check on what we're eating as as we go to the dentist we're always going to the dentist you know here teeth why don't we think about what's going past our teeth and luckily today we have got some tools available to us that help us to do that back in you know when I started it was still bits of pencil and paper where you had to write it down and use books and stuff.

But now we've got apps we can use and perhaps people have used some of those. And in fact, everything has changed and we need to be able to measure what we're eating better. So it's just about the calories. So junior bake-up is not morally abhorrent. As long as you eat small cakes is it about the quality of the calories though so is it okay to eat the same amount of calories if it's a mars bar or if it's

you know because there's this sort of what you're saying about the process isn't it isn't janice absolutely right that that um unsur, for a professor of nutritional epidemiology, let me add my voice to hers. It really is about calories. A calorie of Mars bar is exactly the same as a calorie of junior bake-off poison cake or a calorie of celery. The difficulty is that some of those calories

are quite easy to stop eating. So animals, for example, obesity is essentially unknown in wild animals it simply never happens but how do we animal animals don't have labels that they look at and they are able to juggle their food very precisely and they're not just a healthy weight because of deficiency because there isn't enough food around or because they burn more calories they have very well evolved mechanisms that tell them when they need to eat and when to stop. And we have those...

There are some fat dogs about. Yeah. Wild animals. So wild animals. Definitely pets and some urban animals. There is a beast, you know. And manatees. Manatees, they're all huge.

So, in fact, manatees... Don't they need that, Lubber? No, if you look at humans, the average UK adult human has approximately the same percentage body fat as a sea mammal. So as a whale or a walrus or a dugong or a manatee. So humans in modern Britain have incredible amounts of adipose tissue. And we have these mechanisms,

but the point about some of the foods that you talked about, Harry, without mentioning any brands, is that they subvert these mechanisms. So whilst you can eat a calorie of your chocolate bar, you may be driven to eat another one of those calories and another. So the problem is humans don't eat very well to labels. We've got internal mechanisms that should guide us, but if we don't eat foods that we've been eating traditionally, those mechanisms don't eat very well to labels. We've got internal mechanisms that should guide us, but if we don't eat foods that we've been eating traditionally,

those mechanisms don't work particularly well. So if you, for example, decided you'd eat... So a Mars bar has however many calories, killer calories, I should say. They always offend us. Killer calories, anyway. Killer joules. Killer joules, yeah.

But if you tried to eat the same amount of calories in celery, for example, you'd get bored. You wouldn't eat it. It would be a vast amount. You'd never get anything else done, would you? I thought... I had one idea to kind of cure the obesity epidemic, would be to make narrower doors.

So people couldn't get out. When they got to a certain size, they wouldn't be able to get out and get any more food. You're forgetting delivery services, Harry, I'm afraid. That happens, doesn't it? How cunning you are. So going back to how we know these things, so you mentioned randomised trials,

which is clearly difficult to do, and that's some of your research but in terms of the the response of the body to certain foods um how much do we know about that physiologically is that part of the research where you say well we understand how a certain amount of whatever it is saturated fats and how that's metabolized does that does that matter at all is that important of whatever it is, saturated fats or something, how that's metabolised, does that matter at all? Is that important? I think it is important. It helps us to get another handle on, you know, are we good enough with measuring what's going in?

But we don't have good biomarkers for most nutrients, actually. It's extremely difficult to do. And it usually involves taking blood samples or urine which people don't want to provide so we don't have a lot of knowledge we do know things like fatty liver is increasing but again to actually measure that without doing some intensive investigations it is hard so we don't we don't know as much as we should i think about the physiology behind all of this. And that's usually done in very small-scale studies, not these bigger population-based ones.

I mean, Brian, you mentioned this idea that in the 70s and the early 80s, fat became the demon. Then around 2000, sugar replaced fat as the demon nutrient. And a huge effort was spent trying to work out if we eat one calorie of sugar is it worse for us than a calorie fat in terms of its capacity to drive weight gain and there were these theories that it spiked your insulin and changed your basal metabolic rate and at the end of i would say what 15 years of quite intensive research we're pretty sure we're about as sure as we are of anything in nutrition that a calorie of sugar is the same of a calorie of complex carbohydrates or a calorie of fat or a calorie of protein they all have an equal capacity to allow you to gain weight that's really surprising

actually isn't it it's just counterintuitive have you told anyone else about this i should go on the radio i can't find a platform i've been following that bloke my wife and i've started on that I should go on the radio. But I can't find a platform. I've been following that bloke. My wife and I have started on that Michael Mosley. Is it not Max Mosley? Michael Mosley.

Certainly not Oswald Mosley. My nemesis. Is he your nemesis? No, he's not. Yeah, but he has this theory about, isn't it? It's about, you know, more complex carbohydrates are better for you than simple ones, isn't it? I mean, that's one of those sort of things. Well, that's a slightly different question.

So if you eat complex carbohydrates, they may well satiate you more, and you might eat fewer of them. But that's not the same. Calorie per calorie is the question that the scientists, many of whom are ex physicists actually so the physicists really got into this the nitty-gritty of this question and solved it at a cost of about 50 million dollars that's what we do it was

how are you going to work it out we're going to send carrots and mars bars underneath switzerland at speeds near that of light we We can do it? No! I mean, at the end of the argument between these two pretty eminent physicists about these molecules, we were still left in the midst of a growing obesity pandemic because, of course, it had diverted attention, the row about fat versus sugar, diverted attention away from the fact

that we're being aggressively marketed these foods that are impossible to stop eating, the ultra-processed foods. So in a sense, there was a big distraction going on with the argument about the macromolecules when actually we should be focusing on the marketing and the way the food is packaged and sold to us. But the answer, always the answer to aggressive marketing and perceived baddies normally to increase the price of this stuff

or to ban it or to put a health warning on it is that what you're saying well no i think that thank you for serving me up that low ball and i'm sure janet will have a view on it however we think about the modern food that makes us sick whether we think of it as high fat salt sugar or we think of it as ultra processed the this is essential food for people with low incomes and you cannot ban it, you don't want to do anything to increase stigma you can't tax it and so you have to handle this discussion with incredible

nuance and sensitivity as you've been doing Harry. When we get our letter of complaint from Donut we are going to be in such trouble. I was going to say, because you're a solution to pass a law that only allows one fat kid per class, as far as I remember.

Very sensitive. It's like marketing bans or joinery regulations. You know, that's the way we're heading. So reformulation might be an option, I suppose, where we improve the quality, nutritional quality. What about stigma, though? Increasing stigma. Well, it's...

Just saying that wouldn't work. What we know, I mean, to answer that question, to engage with that really seriously, is we know when we increase stigma, it drives weight gain. And that there is no individual characteristic that drives more stigma when it comes to people's interaction with doctors than living with overweight or obesity.

And I think one of the first things we need to do is change the language we use that people live with overweight and they live with obesity. They are not obese. It's not an identity. And doctors, in particular healthcare professionals, judge people who live with those conditions more harshly than they do because of income or race or any other personal characteristics. So part of the thing we need to deal with is this is not an issue of personal responsibility. This is a failure of government.

It's a failure of the medical profession to regulate the corporations that make us fat. There must be a component of knowledge because, as as, as we've discussed, you know, the, the, those messages that tend to be embedded. I mean, for us in our childhood, as,

as we discussed, you know, I've instinctively think that saturated fat is bad because it was drummed into my mind kind of sub is in the subconscious somewhere. So, so how much of this is about providing that information because, and it must be difficult to follow up question because as we've said it's extremely complicated or is it so is it just as simple as saying calories in

keep them at a certain level i think we need we do need education as well and that's why i was saying you know i think if we if knowing about what you eat was more entrenched within the national curriculum and then people were just able kids were able to say yeah that's what i had and oh that was and you can see the distribution of the class i know it's not answering every part of it but at least it starts to normalize what is a very normal thing to do which is eating knowledge is also about sort of counter information so might we have um a chocolate coated rice puff cereal at home for breakfast, and my five-year-old enjoys it.

And the box says that it's a good source... We have Coco Pops. So the box is intended for my five-year-old daughter because it's got a monkey on it. And the labelling says it's a good source of vitamins, it's got reduced sugar, and the traffic lights, the little labels are orange and green so this is a healthy cereal the problem is that my five-year-old eats four adult portions

for breakfast and people say oh well you know that's bad parenting well any anyone is welcome to come to my household at seven in the morning and negotiate with lyra but you know that's not a hill i'm gonna die on so um the difficulty is that when you're supplying this information you're supplying it against the information that's on the packages so when we talk about uh people's right to knowledge it should include their right to be free from misinformation and i think the problem is a lot of the foods that harm us are sold as healthy as life-giving as important for our health, as promoting weight loss. And actually, they're probably driving significant rates of disease.

I suppose it is quite natural, isn't it? If you see something that is a health food or sold as a health food, you might think, well, so I can eat a lot of that. And it's a healthy thing to do. But as you say, ultimately, it's the portion size and how many calories in that portion that you can eat that's the real issue. Yeah, we've been doing a lot of work for WHO on baby food, weaning food.

And whilst there are controls on what you can advertise to children, TV times, there was nothing for babies. And we know that, you know, the products that are made for babies, for weaning have all sorts of claims on them and describe themselves in all sorts of ways that doesn't actually reflect what's in there so it starts right from day one really what you know that information or potentially misinformation so yeah we need to improve on that i wanted to just ask actually chris we can't leave you know one of the interesting one of the many interesting things about you is that you have a twin brother

and so you have been able to you know twin studies are quite hard sometimes to get through uh you know kind of the the the ethics committee but you've had experiences where you a bit like scott kelly and his brother twin astronauts that you can have different perspectives because you are in different positions different diets and you can see how they affect you yes my brother went to work in the states for 10 years and he went there in quite stressful circumstances he had a he had a new son in an unplanned way it's very happy now but it was stressful at the time and he gained over over a short period of time an enormous quantity of weight and we have the shame genes we have the same genetic vulnerability to obesity we both carry all the genetic markers that put us at risk of that and so when he moved to the states he put himself in this new food environment and that food environment

where food is incredibly aggressively marketed led to this weight gain so yeah twins are a really good natural experiment that demonstrate that people in America are more likely to gain weight. Arguably, other people had shown that in different ways, but it was nice to add to the body of data. It's interesting what you say there, though, because we've talked about just the simple equation at the base level is the amount of calories you eat. So what are the genetic markers that you refer to? So, I suppose a question is if you had two two people just selects at random from the population and fed them the same thing presumably you'd have the same outcome you would and that is it's such an important keystone in the argument that obesity

is nothing to do with willpower because all of the genes that affect our propensity to gain weight are all expressed in the brain. So they're all about eating behaviours. And people will be able to tell if they have any of these genetic risk factors because they will find themselves highly motivated by food. And we all know people who are somewhat indifferent to lunch and can skip dinner. Those of us with these risk factors are obsessed with food. We're prone to, you know, we'll plan dinner at breakfast time and we'll be foodies. So that's how you can tell.

Isn't that what willpower is, in a way? No, because you're born with this sort of innate drive toward food. But the really interesting thing is that the way you inherit those genes, the way they're expressed is entirely dependent on your family income so obesity is heritable in low-income populations and this was all sorted out with twin studies the same genes are not expressed so in high-income families we don't see obesity being inherited and that's because people who live in places with lots of money and have access to good food are much less likely to gain weight. So we see what

the twin studies really tell us is that if we could get rid of inequality and get rid of poverty, we would deal with well over half of the problem of diet-related disease and obesity. Interestingly, I think it's interesting, guide dogs that are most successful are the ones that express some of those desperate need to eat all the time so they can really be trained to that treat so so they're highly motivated so you can teach them exactly what exactly yeah to eat highly motivated to eat i'm very trainable too maybe i'll do anything for a biscuit you know are there other factors that we can all pay attention to beyond the food that we eat in order to be healthy the really interesting thing is that what we're increasingly sure about

is that when you do lots of exercise you don't burn more calories and in fact we've been studying this for a very long time using quite sophisticated double water labeled methods and so when we talk about this energy balance what we're more and more sure about is that while inactivity is very harmful activity if you do lots and lots of activity in your day it doesn't increase your total calorie burn it just takes from your calorie budget which is the same in everyone surely if you run a marathon right then you will burn more calories than if you sit down and watch someone else running the marathon so that is true while you're running the marathon but if we study people over a long period of time what it seems is that if if

you instead of doing essentially a sedentary job in the uk being a physicist and broadcaster if you move to become i have to climb up a lot of mountains what you're saying is that your your average averaged over a week or a month even if you're an athlete or someone who trains quite a lot in the calorie right your calories are determined by your your sex your age and your body composition and if you go and become a subsistence farmer or a hunter-gatherer or a or a miner your calories per day will not change you'll just spend your calories in a very different way so you can go and do your marathon but you spend your downtime burning fewer calories than when you're running.

And we're really sure of this. So the whole idea that when you look at your little watch and it says, oh, you've burned some calories, and you've burned 350 calories on a treadmill, that you can then go and eat one of Harry's bars. They're not my bars. Are you saying do less and eat more butter butter that is very much the message of the show and the title of my next book

can i just put a shout out for fidgeting because we've done some work which shows that if you're sedentary that's not good for you yes but if you are sedentary and fidget then actually that does reduce your risk of long-term ill health yes fidgety person i know and i tell you what i put that in our study 20 years ago because my husband was very thin and fidgeted all the time he now is not so thin and doesn't fidget half as much but we asked a question about fidgeting and if you're sedentary but fidget that seems to help i don't know if you can make yourself fidget fleas fleas is what we want the fleas that you get in the supermarket that's what the whole message of the show is so harry i'd like to know because because we've

reached the end now and it's uh you know how much do you feel we've changed your life from this show today? I feel more confused. I mean, that is astonishing to me, that, you know, if you do a lot of exercise, actually, your spare time is spent. It's still very good for you, because... Well, I don't... What does that mean? Well, so if you're... So I spend...

Your cardiovascular... I'm burning 2,500 calories a day, roughly, every day of my life. And either I can go for a run and spend some of those calories, or I can sit at my desk, and I will then have to spend those calories, like the council road budget, and I will spend them on anxiety, on inflammation, and on reproductive hormone elevation. And if you go for the run, you stop yourself burning the calories on on all those things that we know are harmful so it helps explain why exercise is so good for us which we know it is but it also explains why we've never ever found that exercise helps people lose weight and it

really doesn't there's loads of data but they but you'll live longer you will live longer if you do lots of activity and exercise yeah we're janet yes i do agree although you're going to end up with permanent injuries you do your knee in this is not the public this is the best show we've ever done um the uh a fidgety man who loves eating small yogurts has never been happy harry now we also asked the audience a question today, and we asked them, if you could make one food truly wholesome, what would it be and why? What have you got, Brian?

Strawberries dead or alive. Excellent. Let me process this question. Oh, yes, processed food. Swiss cheese, because it has some holes in it and would be much better if it were wholesome. Turkey Twizzlers so I can

prove Jamie Oliver wrong. That's from Cameron who's in two seats. Thank you very much, Harry. Thank you to our panel there. Harry Hill, Janet Cade and Chris Van Tunican. Our next week's show, we are dealing with super volcanoes, which means just a lengthy selection of anecdotes

from Brian about all the volcanoes. Tell us one of your volcano stories while I read most of Crime and Punishment. Funny thing happened to me, aren't we, at Volcano? Oh, buddy. Thank you. Bye-bye. APPLAUSE In the infinite monkey cage. Without your trousers. In the infinite monkey cage. Turned out nice again.

Hello, my name's Michelle De Swalt. And I'm Laura Smith. And we have a new podcast from BBC Radio 4. Bang On It is a weekly podcast where we curate, recommend, cherry pick through the week and just go, have a look at that. Basically. We're going highbrow, we're going lowbrow, right? We're doing the legs. We're doing the hard yards so you don't have to.

Oh, I like that. Listen, like all podcasts, we're talking about stuff we've done, whether you should bother doing it, but really we're waxing lyrical and... Trying to make that paper, baby. The economy's in the pan. Subscribe to Bang On It on BBC Sounds.

This is the first radio ad you can smell. The new Cinnabon pull-apart only at Wendy's. It's ooey, gooey and just five bucks with a small coffee all day long. Taxes extra at participating Wendy's until May 5th. Terms and conditions apply. Tax is extra at participating Wendy's until May 5th. Terms and conditions apply. In our new podcast, Nature Answers, rural stories from a changing planet,

we are traveling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers wherever you get your podcasts.