Obesity: the gene-environment debate

Hello, and welcome back to Mind Over Chatter, the Cambridge University podcast. I'm James I'm Nick, and I'm Annie, and once again, we're inviting you to join us in our conversations with clever, curious people here in Cambridge. In this third series, we're talking about health. And in this episode, we're focusing on obesity.

We're going to cover everything from why some people are genetically more likely to gain weight than others, the important role the environment plays in influencing what we like to eat, and how communicating information about obesity doesn't necessarily change our behavior. So who are we talking to in this episode?

A health psychologist: Hello, I'm Theresa. I'm a psychologist and behavioral scientist. Hi, I'm Tom. Uh, I'm a Senior Research Associate in the MRC epidemiology unit and a commission. I am Sudan. I'm a Professor of metabolism and medicine.

We began by asking our guests to tell us about their research.

Yeah, I'm interested in trying to find out why some people are much more likely to gain weight than others.Uh, how that's influenced by our genes and using genetics to try to find out the systems that the body has for controlling a person's weight. My work, as I said, is, is focused on understanding the social and particularly neighborhood kind of determinants of diet and health. Um, but I do a lot of work in the evaluation of public health interventions, and really, I have a key focus on translating that evidence into, um, public health policy and practice where.

I'm interested in identifying the cues in our immediate environment that shape our behavior often without our awareness, such as the size of a pizza or a wine glass, and often to the detriment of our health. And I'm interested in identifying those cues in order to work out the cues that could be removed or added to our everyday environments with a view to changing our behavior and improving the health of everybody.

Let's start by understanding what obesity actually is. So dad, could you tell us what it means to be obese?

Sadaf: Yeah, so obesity is when people have too much fat, to a level that then affects health. And because it's not that easy to measure the actual amount of fat, we tend to use heightened to calculate a person’s body mass index or BMI, and that's a useful surrogate for the amount of fat someone has in the body. And so we know that if someone has a BMI of more than 30, that equates to obesity, and that equates to an increased risk of certain conditions, like type two diabetes.

Can you give us a sense, along with diabetes, of some of the impacts that obesity might have on us?

Guest: Yeah. So obesity can impact a person's health in many ways. So there's an increased risk of type two diabetes, high blood pressure, heart disease, actually, even some forms of cancer are more common in people who struggle with their weight. Indeed obesity is likely to overtake smoking as a major cause of cancer in many countries. But obesity is also linked with impact on the joints, impact on breathing, impact on hormone levels, and importantly depression on wellbeing. And there’s a substantial stigma actually associated with people who are severely obese. So reading a recent review, I think it's also one of the 12 modifiable risk factors for dementia. So effecting decline. It's a major association with dementia, motor neurone disease. Absolutely.

Right. And roughly sort of how many people, either in the UK or worldwide are obese?

In the UK it's between 20 to 25% of the population are clinically obese,using that definition of a BMI of more than 30. And actually if you relax the definition a little bit to say how many people are overweight or obese, then that's about 50% of people. So it's really a large portion of our population. The same is true in many countries - developed countries, Western countries. And of course the prevalence is rising in many countries around the world, for example, in Asia, and already is quite high in the Middle East.

And how has the population changed, like how heavy are we compared to say 20 years ago? Has that changed over time?

Sadaf: So, yes, it has changed if you look at the population trends. And Tom and Theresa may also want to input here, is that two major things have broadly changed. So the average person is heavier than they used to be - children and adults. Okay. But also there's a change in the distribution. So there was, there's always been some people who are particularly heavy, and some people actually who are particularly thin, but now what we're seeing - and it's driven by the changes in our environment - is a greater proportion of the population have obesity, and indeed severe obesity.

Host: This might sound like a bit of an obvious question, but how exactly does what we eat and how much we eat affect us? So are people are basically eating too much, or is it because they're eating the wrong sorts of foods?

Guest: So basically the reason that people gain weight is an imbalance between how much you eat and how many calories you burn. Okay. Um, but the imbalance only has to be quite small and do that consistently over time to explain the trends in the population that we see. So everyone's sort of imagined that we must be eating absolutely loads and doing absolutely nothing. In fact, that's not the case, it's a small imbalance, across many, many people that explains entirely the changes happening in the population. Now then you could look into, okay, why are we eating more than we're expanding in terms of energy. Well, of course our environment has directly changed in the last 20 to 30 years. The type of food, the fact it's cheaply available, easily available, the amount of food, the calorific content of the food. So all of those things are combined really. And of course we're much less active than we used to be. So both at work and in leisure time. And so those changes add up and then the balance basically tips. And then the other factor underlying that is our genetics, that genetics hasn't changed, but our genes influence how we respond to the environment. So in the same environment, some people were much more likely to gain weight than others.

Guest 2: Another thing that I would add to that Safaf really occlude to. What might be driving. Some of these changes is the pattern of obesity in different places. And what we can see is that those living in areas that are least affluent have higher rates of obesity than those living in more affluent areas.

If we come on now just to say little bits about childhood obesity, only last week, the latest figures were published from the National Child Measurement Program, which is a fantastic program which gives us data on a regular basis, going into schools and weighing children. And those figures were really shocking. And what they showed was that over the last 12 months during the pandemic, there's been a full percentage point increase in the proportion of children aged 10 to 11 who are now obese, having gone from, I think it's 21% to 25%. And just to illustrate the point about the social patterning of obesity, it's around 33% of children in the least affluent areas who aged 10 to 11, who are classified as obese, compared with just a 14% in the most affluent area. So you can see it's a huge, huge divide.

Yeah. They are really shocking. Almost the inequality is more shocking than the absolute rate, which, you know, to some degree, certainly before the pandemic might have been seen to be kind of leveling off in that kind of increase in trend that we've observed.

But the inequalities have always kind of been increasing and I don't think have leveled off yet, but I guess as Theresa said, like the clue might be what people's neighborhoods look like possibly. So in those deprived areas, You know, we've got 50% more fast food outlets, for example, compared to those more affluent areas.

And perhaps that's playing into why we've got almost 50% more obesity. We've also got less green space, fewer parks. We've also got more dangerous streets as reading the other day that passing pedestrians are three times more likely to be injured in the least affluent areas compared to the most. So I think looking at those immediate environments, both the food environments and the physical activity environments is, is going to be key to thinking about what we can do to hold the growing gap between the richest and the poorest, um, and start to reverse.

Host: Do we think that gap is all environment? So, you know, in some ways it seems perhaps a counter-intuitive idea that those in some of the least affluent environments those who are suffering worse from obesity, the highest prevalence of obesity, is it just environment? How do we understand that, that difference?

Well, it depends what we mean by environment. So just to be really academic and awkward about it, our environment might be our household, it might be our family. It might be our neighborhood. It might be the country that we live in. Right. I think Sadaf might have a different idea of what our environment is, but, you know, it's the bigger picture and it's all of these things that come together to shape kind of what we are.

How much exercise we do. One of the factors, whether you causing five. Poverty. Um, some of the work that Tom has done has shown that low income is an independent risk factor predictor of obesity and low income can work in several ways. There's been some really interesting studies that have been conducted, looking at how poverty, drains of mental capacity, ability to think about other things say, some studies that were done a few years ago, looking at Indian farmers, cane sugar for. And giving them challenging cognitive tasks. And when they were given these immediately before a harvest where they had little money, and the families, they did much more poorly on those tests than after the harvest had come in. And what they were able to do was to control for nutritional status and various other things to show you that actually, I mean, it seems common sense that if you're concerned about getting enough money into your household, you can't be thinking about, should we go out to the park to play or thinking about, um, buying food to prepare a meal from scratch.

It's also another, unfortunately not that much evidence, but from natural experiments whereby when smaller. Of income comes into the poorest households, sort of intriguing sort of counter-intuitive findings that those households then reduce their spending on tobacco and alcohol and increase their spending on fruits and vegetables.

And it's thought that that might work by reducing stress in those families. So as well as the immediate food environments and activity environments, I think we shouldn't underplay the role of having a low income and how that can affect all of the behaviors we're interested in.

Healthy foods do, in general, tend to be more expensive. So, you know, if you are extremely price sensitive, if you only have a limited budget, you know, you can get an awful lot of calories, for example, in, in your local kind of fish and chips shop or fast food outlet or whatever for a pound, you know, like if you, if you're looking to just feed yourself, um, actually the paradox is that you probably end up eating kind of energy dense nutrient poor food on a limited budget.

And is that the case everywhere? Is that a particularly British phenomenon? It's not a British phenomenon. Um, but I think that the, the, the gap perhaps, um, is one, we have one of the largest gaps in terms of, um, the proportion of people, both at the lower end of the socioeconomic deprivation and high-end, uh, and, and I think.

You know, in the US and other countries also, they see the same thing. So across globally, obesity rates are higher in areas with socioeconomic deprivation in the UK, um, amongst other countries in Europe, uh, we have the highest proportion of food that we bring into our house that is ultra processed. I think it's 52%.

So in Europe we are outliers in terms of, uh, some of our foods. So what then does a healthier country look like? That's a great question, but it's a big question, right? It's a, it's almost, it's almost a completely different country to the one that we currently exist in, to be honest in almost every single way.

Um, you know, my, my, my research focuses on neighborhoods and that's what I'm interested in. You know, so I'll speak to that. I think a healthy neighborhood is one in which healthy choices are the easy choices, because the easy choices are the choices that people will make more often. You know? So at the moment we have a situation where actually the unhealthy choices in most neighborhoods with the easy choices, um, and actually healthy choices are almost impossible to find for some people, you know, it might be the in one's neighborhood.

50% of what I have available to me is fast food. And that, that, that isn't, you know, that isn't making the healthy choice, the easy choice. So, um, I think that we need to radically change what our neighborhoods look like in order to kind of encourage people to make those healthy choices. Mind if we pause a minute to gather our thoughts, not at all.

So we started off with definition of what. With the definition of obesity. Yes. Always a good place to start, especially with academics, they like definition. Yeah. We heard that obesity is the name given to the situation. When the amount of fat someone is carrying begins to affect their health. It's not particularly easy to measure the amount of fat directly.

So we use other measures, a common one is BMI or body mass index, which is calculated using your height and weight. You can work out your BMI online. If you're interested. If someone has a BMI of more than 30, this would mean they're obese, which in turn increases that person's risk of certain health conditions such as type two diabetes.

How else can a Beastie affect our health? We heard that obesity can cause high blood pressure, heart diseases, and even some forms of cancer. Yeah. Apparently obesity is likely to overtake smoking as a major cause of cancer in some countries. Uh, obesity can also have an impact on the joints, breathing and hormones.

And in some cases can lead to depression. Unfortunately there's substantial stigma attached to severe obesity, which is one of the reasons why mental health can be affected. Obesity has also been associated with dementia and cognitive decline. What do we know about how many people are obese? Somewhere between 20 to 25% of the UK population are clinically obese, which means they have a BMI of over 30, but if you relax the definition of.

And instead ask how many people are overweight or obese, then it's about 50% of us. So a significant proportion of the population that yet are afraid of. So probably a significant proportion of this zoom room too. And the same is true in lots of other countries with the number of obese people rising across the world.

So obesity is on the increase, but how did we get here? Well, so the death toll is about two major things that have changed in the last 20 years when it comes to obesity thing. Number one, the average person is heavier than they used to be. And this is the case for both children and adults thing. Number two, there's been a change in the distribution.

There've always been people who weigh more or less than others, but we're now seeing a greater proportion of the population suffering from obesity. And what did we learn about how we eat and how much we eat affects? On a basic level. People are obese because they either eat too much or eat the wrong types of food, but the picture is not quite that simple.

So now I've told us that our environment has a big impact. For example, the calorific content of food has increased over the last 20 to 30 years, as well as how easily available it is. Another important factor is genetics. Unfortunately, some people are genetically more likely to gain weight than others.

Theresa also told us about how income affects obesity. People living in less affluent areas have higher rates of obesity than those living in more affluent areas. This makes sense. If you remember that healthy foods tend to be more expensive. So if you've got a low income, you can get energy, dense nutrition, poor food, very easily.

For example, from the local chippy, Tom also highlighted that there can be 50% more fast food outlets and deprived. Compared to more wealth areas, which might impact obesity, right? So daft raised the point that, although this isn't a British phenomenon, we do have one of the largest socioeconomic gaps between the rich and the poor, the USA, for example, see similar patterns, but remarkably in the UK, we have the highest proportion of food that is ultra processed and other things that we can do on a kind of micro level.

Or is it more that those kinds of changes have to happen on a more macro level to do with policy and go. Thinking about just sticking with what Tom has said, talking about neighborhoods and very crudely. I think sometimes it's helpful to divide up the world into a commercial sector. So there used to be the shops.

We go into the cafes that we frequent, um, and the public sector and say that would be schools, um, hospitals. And of course we all know that the world isn't quite that simple, but let's pretend it is simple for the moment and thinking about the food courts in some of our hospitals, um, they would be a great place to be able to start and to actually model what a healthy and sustainable, um, set of foods would look like.

Um, and to take that as a way of modeling to people, because I think most people have got absolutely no idea what a healthy portion might look like, what a healthier set of foods would look like. Um, and I think in that way that people would begin to see what it is that we're missing and where we're trying to, uh, what, what, what kinds of changes we we're trying to make in terms of your question about whether this is a individual, many people focus on the role of governments and policymakers in terms of setting the food environment.

Okay. Um, so there's some recent examples from Singapore, for example, where they. Brought in to place a series of policy changes, which are about changing the local environment, which is everything from a Watson, but actually they've got buy-in of course it's a small place and you can control and regulate many things.

Uh, what is being provided in supermarkets? Uh, also the pricing of foods, as well as the opportunities for activity in the workplace. So for example, uh, as well as in schools, so, you know, people in a way are doing some of the large scale kind of experiments in a way as part of policy changes, um, and the Singapore experiment, so to speak, I think will be quite.

They actually have quite relatively lower rates of obesity, of course, compared to us, but it's risen from what it used to be. I think it's a real challenge to translate some of the research, um, fat changes of food in bars. That could improve our health. So just to give you a couple of examples from research in my own group, um, recently, uh, we conducted a study in 19 worksite, uh, cafeterias, and these were, um, distribution centers for a major supermarket group.

And, uh, they were used by the vast majority were, um, non-managerial manual workers and also men. So a group that have a higher rate of obesity than there's no sin in those groups. And, um, these worksite cafeterias were used by Ava, 20,000 employees. And we did two things. Um, first of all, we shifted the proportion.

Of high energy foods to lower energy foods. So for instance, four main meals, um, we, uh, took, uh, just to, uh, a rough example in most of the cafeterias around three out of four of the main meals were. 530 calories. So what we did was we shifted them to having two out of four that were above a 530 say to have more that were, uh, at five 30 or below.

And for the desserts capping those at 310 calories. So say the same number of meals were being offered, but you just had a greater proportion that were lower calorie. Um, we did that for awhile and then for the high calorie, uh, meals, we then cut the portion size by about 10% say people didn't really notice these changes.

And what we found was that over a period of 25 weeks where we were running the studies that we reduced, the colors that were being bought in across all these cafeterias by just Ava 11%. So that's an important difference and worth going for. We publish that we've published similar other studies, but these findings aren't necessarily adopted.

Um, and it's, it's, that's the challenge really as to how to do that. Just to give another example where not only were the findings not adopted, but actually the unhealthier options were, um, became more common in a series of experiments. We've conducted restaurants, looking at how the size of wineglasses affects how much alcohol people consume that.

Not for children or most children, but for adults. Uh, for those who consume alcohol, it's an important contributor towards obesity. Um, for those who consume alcohol, it can be between five and 10% of their energy intake. So we were interested in how the size of wine glasses. Doubled over the last 30 years affects how much people are drinking.

And what we found is that in restaurants where they're serving usually bottles of wine, serving the wine and smaller wine glasses, um, does reduce how much Y people are drinking, uh, by about 7%. Uh, so a wine glass that is a 300 milliliter capacity compared with 370 millimeter capacity. Now, when we conducted the first experiments in, uh, the pint shop in, in Cambridge, um, the owners, uh, found it really interesting.

And, uh, they, uh, what they did was they got rid of their smaller wine glasses. And why wouldn't you? Because they could increase their sales. And I think that there's importantly points out the asymmetry of evidence. That's needed for public health intervention. So one study absolutely isn't enough to start regulating, but it is enough in the commercial sector.

Um, to capitalize or what might be. And they were that you write a, is a finding that was replicated. Um, I want to ask, so you've told us a little bit about the pint shop, which I know personally, you've talked to us about work-based cafeterias, for example, but I want to talk perhaps a little bit about schools and educational environments and ask staff about, um, the education around food diet and exercise within schools.

So can you tell us a little bit about that and maybe about how education about and around obesity might affect childhood obesity? We've touched on canteens a little bit that we didn't touch specifically on school candidate. Uh, and why they're a particularly challenging kind of challenging space. And I think actually a lot of the challenges with school continues is keeping kids in the canteen at lunch because they're not, you know, it doesn't really matter what they sell.

You know, they're not cool places to hang out the atmosphere often. Isn't great, you know, um, and they would rather leave the school grounds at lunch and go and hang out at the local takeaway because it's more appealing and it's a better place to socialize. So, you know, it's all well and good kind of improving what's on the menu, but it's, it's actually about keeping them there so they can benefit from those improvements.

There, we'll say this trials that are being conducted in schools over the last 10, 10 years, um, they've been very, uh, elegantly designed that have looked at. Uh, changing both the theater environments and also just the whole school day, uh, to increase levels of activity in the school children and sometimes the teachers.

And what those are telling us is that so far, those interventions are not having a measurable impact on levels of physical activity or obesity in children. And it's drawn attention to the wider environment that maybe those active schools would be more effective. If the environment outside of school was also supporting, um, healthier food environments and more physical active, Perhaps kids are healthy when they're not at school because they're not spending time in and around the school, which is kind of where takeaways are clustering in order to capitalize on the student pound.

You know, there's a, there's a disproportionately greater access to takeaways around schools than there is in other areas. So that's an interesting, concerning worked consuming works because there has been to cough keeping fast feeds away. Uh, it's no more than 400 yards from school. So, yeah, that's right.

Um, whether it's worked is the question that we're answering right now in our research, but we know that 40 or so local authorities out of 320 in England at the moment have implemented so-called exclusion zones around schools. So going forward, no more new takeaways will be allowed to open. Um, That's that's, that's an ongoing question.

We'll find out in the next couple of years, whether that has worked, of course, there's already an existing high number of takeaways. So you would almost certainly, I think to have a real effect, need to intervene on what's there as well as what, you know, what is, what is new to those environments. Um, but again, that just reinforces doesn't it there, the need to have multiple complimentary interventions across in lots of different ways in order to really tangibly.

Yeah. Oh, I was just, I was going to pick up in terms of how we respond to information and communicating risks. Um, and, uh, what we know is that, uh, it's, it's a very, um, popular intervention, both with governments and dorsi with general publics. We love, you know, we're very happy for governments to give us information, but, uh, while it increases our awareness of a problem such as, um, our dots and how they're affecting our weight and our health it's it's, uh, it doesn't, it doesn't change our behavior.

And, and this is fascinating so that that's led people to think, oh, well, maybe it's because the information is too general. So you're telling people to eat five pieces of fruit and veggie day. And certainly we're much more aware we should be doing, doing that, but when it's evaluated, it's it doesn't change.

So it, it, it led to, um, a lot of, um, interventions to personalize the risk, um, using genes and other biological markers. Um, and, and say some of the, um, the best, uh, studies are being conducted by colleagues of mine here in, in Cambridge, where taking a group of often, uh, middle-aged, uh, adults and assessing their risk of developing type two diabetes in the next 10 years.

And, uh, uh, giving them that risk and telling them that if they increase the levels of physical activity, maybe lose a little bit of weight, they could reduce those risks and. Actually it doesn't change the behavior. Um, and it's, it's such an important finding because what it highlights is certainly what a psychologist we've known for the last 50 or more years, which is that we are much more influenced by our context or immediate surrounds than what's inside our heads.

So again, this draws attention to the need to look at the triggers in our environment, the cues in our environment that are leading us to either consume. So there's not a reason I just emphasize I'm not against education at all. And digital working in a university, uh, that would be slightly problematic.

Um, but in terms of changing our behavior, I, it doesn't do it, but it's very important that people are aware, uh, of, of the risks that they they've. So I would add a slightly more different moral sort of more power, well explanation for what you just described a RESA. So, absolutely. And several studies have shown that once we like to think that explaining to people, the risk might cause a change in bring about a change in behavior.

Many studies have shown that doesn't happen necessarily. So it's interesting that you concluded that, um, it's kind of your environment that is therefore influencing what you do, but I guess the other conclusion is it's also your biology that is influencing what you do, right? So, and of course the two are not separate, so or three are not separate.

So, you know, one of, one of the challenges with advising people to change diet and activity, and assuming that that's sufficient, and that actually has been the coolest own of policy in the UK. And many of you know, this personal responsibility, um, is. We assume that everything is under voluntary control and the people will, therefore if given the information, be able to do this and enact a change.

Um, but obviously their environment may, if it's drained, unchanged is a kind of competing influence. But the other thing of course is your genetics and your biology. So what we and others have shown is that actually how much you eat. How full you feel, uh, or traits that are strongly influenced by our genes.

Okay. And so people are often quite surprised about this because we tend to think that how, what we eat and our eating behavior is voluntary. Actually, part of it is voluntary. And part of it is learned from exposure in our environment, but a strong part of it is biological. And we know that and, and many people have done studies for example, in twins.

So if you take identical twins, they tend to have a very similar body weight as adults, even if they're separated at birth and live in a completely different environment. So very elegant studies from Jane Wardle in London showed that if you look at children who are twins, uh, they have a very similar body weight, and it's actually to do with them being a twin and the genetic influence rather than the shared childhood.

Which everybody assumed it was down to the childhood environment. Actually it's down to the much more down to the genetics, the news town, the childhood environment, and our genes affect our weight predominantly by effecting our appetites. Okay. So how hungry you feel, even if you're given the same amount of food, how full you feel after that meal is strongly genetically influenced?

So it's very similar in twins. Okay. Um, and so one of the challenges is that you can advise people, but if they are on the court, a lot of people have a tendency to want to eat more. Um, and the things that they might choose to eat are strongly influenced by the environment that we live in. Then actually it's quite hard to fight against that.

And I think that's almost like the kind of pulling together of the lessons from our different areas of research. Um, and that's something that we've been trying to see if we can bring that kind of broader view. To influence policy, because I think if policy changes are only about telling people what to do and saying, it's your personal responsibility, it hasn't worked for at least 30, 40 years, and it's unlikely to continue to work.

Just shouting a bit louder is unlikely to enact a change. I think there's a, a great, uh, balance to, to what I said, uh, Saddam and thinking about really the gene environment interaction. And I can't remember, it might be you, you know, um, the islands for which a large number of people went to the U S and, um, because they had a genetic predisposition to obesity that wasn't evident in the, uh, original, uh, place.

Um, Um, the finding itself in this obesogenic environment in the U S high, high rates of obesity. Can you remember what which I said, I mean, it's actually happened in pretty much several, several ethnic groups. So every ethnic group that has migrated to the U S has changed, has seen a dramatic change in that prevalence of obesity.

Um, but of course the, the degree of change is also varied across the ethnic groups. So some groups are much more susceptible than others. So there's a group that we're in, in which many studies have been done called Pima Indians. Uh, and so they have a very high risk and they've come from parts of Mexico, for example, and Mexican Americans have the same.

Um, so all ethnic groups have a higher risk when they moved to an obesogenic environment. But the there's a graded response depending upon your genetic, you know, we're hearing from sedan, how and why genes are really important when it comes to obesity. We're also hearing from Theresa how the environment can pattern what we might consume.

Tom has a geographer who looks at neighborhoods is clearly also focusing on the environment. But how do you think about this interaction between our genetic disposition to, to eat in some way, if I can phrase it like that, and then the way in which the environment influences that eating behavior. Yeah.

It's entirely possible. Isn't it? That for any given level of exposure to one's neighborhood, for example, some people will be more or less likely to use those cues, right. And to act on those cues in the environment and maybe genes have a, have a role in predisposing, some individuals more than others, just as having a low income or a different level of education might kind of predispose somebody to youth.

Types of, um, types of environments. Um, so, but it is hard to say it's really hard, isn't it to say, well, this fear, these, this particular set of factors contributes X and it's more or less than this other set of factors. Right? It's you know, the key question is, you know, does this, does this risk factor kind of contribute?

And if so, you know, we need to act on this as well as acting in these other spheres. Um, what we've been doing certainly over the last seven or eight years is studying neighborhoods quite closely and really focusing in on, on fast food exposure. Um, and what we have found in big studies of kind of up to 50, 60,000 adults is that people who, uh, groups of people who live in neighborhoods with the most take-aways are almost twice as likely to be a BESE.

And on average kind of 1.2 units of BMI heavier than those who are least. To take away. Um, so you know, what we've started to kind of unpick is that, that there is probably all the evidence suggests there is probably a role for the neighborhood environment in kind of shaping what we eat. But it's really hard, at least for me to kind of stack that up against the genetic determinants.

I don't and say whether it is more or less important, but it contributes. Well, I think the key is it's not, it's not one or the other. Okay. So, so the key thing is not genes versus environment, which is how it's tended to be phrased in, in many diseases, many traits, uh, it's actually genes and environment.

Um, so genes clearly play a major role. We have children referred to me with severe obesity. Countries like Sudan from rural India, you know, developing severities to because a single gene is not working. So there's a strong genetic influence. And then, you know, that's relatively rare, but across many people, there are lots of different genes, which own the added together influence your risk of both obesity and also staying thin actually.

So we've shown that being very thin is as heritable as severe obesity. Uh, and there are people who are thin have less of the genes associated with obesity and have additional genes that are keeping them thin. So genetic factors act right across the spectrum. Now, of course, our environment, the immediate food environment as Tom described.

And of course, the way for example, that, uh, Theresa described cues and you feel like, um, you know, things in our environment influence our behavior, our rule interacting. Okay. And one of the ways they're interacting is if you're. Genetically susceptible and you have a big appetite, so to speak. Okay. Then if those kinds of foods are the ones that are more readily available and you're being exposed to certain cues, which might encourage you to want to eat those foods, then you're the kind of person who's much more likely to gain weight.

Okay. And we're talking about foods. We tend to think that it's just this, the food is available and the person is making the bad choice, so to speak. But actually, you know, there's biology underlying what food you choose. Right? So, uh, we and others and Theresa and I have done some collaborative work on this kind of space as well.

Um, you know, your brain will prefer things like high fat food or high calorie foods. Okay. And so it's not a new, just down to what we tell people is in the. Oh, how we advise them. The actual content of the food will trigger different responses in the brain. So you can put somebody into a brain scanner and you can visualize that.

And you can see areas of the brain that lights up would say a high-fat milkshake versus a low-fat milkshake, even when you control for other parameters, like the taste and the sweetness and the, the, uh, the mouth feel of the milkshake. Um, so, you know, we like foods that are rewarding, uh, often with high in calories, behind fashion.

Of course, the food companies know this much, and this is why we will eat more of certain types of food. Um, because it's rewarding for us. I think as, as, as, um, you were saying Sudan, it's the gene environment interaction and. Where can we intervene, um, with some of the extremes, uh, you've done some innovative work where you can, uh, identify, uh, deficiencies and intervene, but actually for general populations where we intervene is in the environment.

Um, and it, it will likely have a larger effect for some, some of these, uh, individuals that have that genetic load as it were. But it's, it's about, uh, changing, changing our environments, both our food environments and, um, our activity environments. So I would, I would agree. I mean, I think, I think what's happened to date is our policy has been only about thinking about the environment and as it.

All the things that we've discussed, that actually, it's not as simple as just telling, changing the environment, which we haven't actually done, uh, or telling people what to do in that environment, because actually it's all of these complicated factors. So, you know, a policy maybe at a simplistic level has to both influence our environment and what we're exposed to, to have an effect on as many people as possible.

But it has to recognize that it's not, um, you know, a simple thing and the people are different both in terms of the genetics, but of course also in terms of the money they have available, that's a massive factor. Um, and there has to also be a policy that is recognizes that, that won't be sufficient for people with severe obesity who have healthcare needs and who need medical care and medical treatment.

And that's actually been something that's been quite neglected in the. So, you know, given the complexity and given the number of people involved, who are affected and the fact that we need to reduce the number of people who will be affected in the future in particular children, um, a very joined up strategy is really what has to be, um, colleagues, colleagues of ours in, in Cambridge have recently done an analysis of a Beastie strategist in the UK over the last 30 years.

And, uh, we've, we've had 14 strategists and nearly 700 policies. And as we described earlier, Rates of obesity have not stalled and in children they've actually increased. So that raises the question. It's I don't think that we're stuck for ideas and much of what we've talked about just now have been included in recent independent reports and government strategies.

I think the problem comes with some of the least effective interventions have been implemented in some of the information based ones and those that have been implemented, haven't been implemented, uh, you know, at, at, at scale. So I, I think that there's a real. Problem, which probably goes beyond our expertise to think about the political economy, the political science of implementing policies that are going to make a real difference, but there have been some successes, right?

Theresa. So for example, the, the UK soft drinks industry levy, which I guess some of your listeners might know it's kind of a sugar tax. Sugar-sweetened beverages, you know, like, uh, members of my group have evaluated kind of the success or my marker of success at that intervention kind of one year post adoption and, you know, households in the sample that they studied were consuming, you know, 10%, less sugar, you know, but they weren't drinking any less soft drinks, any fewer soft drinks, they're still drinking the same volume of soft drinks.

The, the industry is still selling the sale, same volume of soft drinks. So they're quite happy, but the reduction in sugar is 10% and that's because this tax wasn't passed on to consumers instead it carries reformulation of the product. Right. So kind of everyone wins in that example. And it's, it's, it doesn't rely on the individuals to do anything, to engage with this intervention, you know, that they're being offered healthier products and, you know, it's kind of a win-win and that, that at least kind of one year post intervention in this, uh, That seems to have been tremendously successful.

I completely agree. But during the same timeframe, as I recall, sales of chocolate and confectionary have gone up say that doesn't counter what you're saying at all. What it's saying is that here was a policy that was effective, but we need lots of policies in order to change the food environment, say that we've got the healthier foods that are available and affordable and say, it's really going at scale with more than one intervention.

Okay, let's pause again. What did our guests have to say about possible interventions to deal with writing levels of obesity? We heard that food courts in public sector buildings, such as hospitals, for example, could be great places to model healthy food and healthy food environments to people. Teresa also spoke about the challenges of translating research that's been done on food environments, into useful policies.

She gave examples from work site cafeterias, where we tend to see higher rates of obesity as part of a study. These cafeterias offered more low calorie meals and cut the portion size by 10%. It turns out nobody really noticed to see that study ran back at the Dolan household. They would, I confidently predict the revolution.

Unfortunately, these important findings and others like them, haven't really been adopted. In fact, sometimes unhealthier options were actually adopted after some of these, like these. Yeah. Theresa told us about an experiment where a pub in Cambridge offered smaller wine glasses, which reduced how much people drank by about 7%.

I left early after getting tired, pouring so many itsy bitsy, tiny glasses from their regular sized bottle and the wine glasses with simple sized, all the cars, they lost their voices ordering so many tiny, tiny glasses of wine. Again, I think you're overestimating how small these glasses, apparently the pudding question, the pint shop took advantage of these results to invest in larger wineglasses, to boost their sales and who can blame them.

And what's the deal with schools. As far as I'm aware, schools did not invest in larger wineglasses as a result of this study. That's that wasn't really what I meant. Well, we heard that canteens are not called places to hang out and here comes the crushing realization that my love of the canteen was yet another way in which I was, was hounding the uncool at school.

So this there's a disproportionately higher number of takeaways around schools than they are in the areas, which is how we got onto zoning. The effort to keep fast food outlets, no more than 400 yards from schools, 400 yards being about as far as anyone has ever been able to propel a burger through the air, without it disintegrating, due to air resistance or being eaten on route by a passing seagull around well, it's the local authorities out of the 320 in England.

Have implemented these fast food exclusion zones around schools, which mean that going forward no more new takeways will be allowed to open. We'll find out in the next couple of years, whether that has worked, obviously there's already an existing high number of takeaways and obviously burger cannon technology may yet improve.

Especially if my most recent patent application is successful. I shut her up. Theresa noted that communicating information about obesity doesn't necessarily change our behavior. This highlights what psychologists have known in the last 50 years or more, which is that we are much more influenced by our environment that what's inside our heads.

What many of us have known since the late eighties, which is that a room full of Twix is, is like a room full of Borg. Resistance is futile. So that's agreed not with James's room full of Twix is, but with Theresa who also argued for the influence of biology, how much you eat and how full you feel are traits that are strongly influenced by our genes.

People are often quite surprised about this because we tend to think that how we eat and what we eat is more or less voluntary apart from when you were at relatives, in which case, eating as apparently entirely involuntary it's of how and what we eat is voluntary. Part of it is learned from exposure in our environment, but a strong part of it is biological and patterned by R G.

Although it is important to note that personal responsibility thing, two environments, and three biology and genes. These three are not three separate things. In fact, Sadat noted that, although it's simply isn't enough to advise people to change their diet and activity, this has unfortunately been the cornerstone of UK policy in this area in recent years.

Instead, these three things must be considered together in order to make an impact on obesity. Be fair to argue that the best place to intervene is in those places where our genetic predisposition and our environment come into contact. Yeah, that's what Teresa said. We also need to remember that even if a policy recognizes the role of genes and how these will vary from person to person.

And recognizes that the environment needs to be changed to help people make better decisions. The people's choices will still also depend on their income and healthcare needs. We need a very joined up strategy. We're not stuck for ideas when it comes to obesity interventions. In fact, a lot of what our guests talked about has been included in recent independent reports and government strategies.

The problem is that some of the least effective interventions have been implemented and the political science of implementing policies that are going to make a real difference needs to be. Tom reminded us that there have been some successes though, for example, the UK sugar tax. This was a win-win for both consumers and the industry because drinks companies still sell the same amount of drinks, but these drinks just have less sugar in them.

The same could maybe be done for other foods to going at scale with more than one intervention as Teresa. We've talked about interventions that have to do with environment and policy and how they are linked. But if obesity is to do with genetics as well, can we find better ways to prevent and treat obesity through genetics and other pharmaceutical or surgical interventions that we might use in the future?

Um, so in response to your question, it's not, if it's genetic, it is it's fact, okay. It's not an idea or a theory it's fact, um, scientific fact. So, um, I think the knowledge that obesity is that I'll wait, is strongly influenced by our genes, um, can guide us in a number of ways. So I think the first and most important way it can guide policy is really.

To understand the complexity of why people gain weight and why some people are much more likely to gain weight. So it's a really about the approach. So it's about the approach to a policy which relies solely on personal responsibility and thinks that that will be enough to solve the problems we have with obesity.

It's highly unlikely to be sufficient when there is a strong biology underlying what we do and how we behave and how we interact with our environment. So I think that's the major contribution that understanding genetics makes. Um, and then the second area where the genetics can make an impact is in the treatment of people with severe obesity, right?

So that's a smaller proportion of people. Um, it's still a million people, um, but people with severe obesity that is much more likely to be just strongly genetically. Uh, and those people are much more likely to benefit from treatments because simple changes in diet and exercise are unlikely to be effective in many of those individuals.

So I think that's the thing. And then there's a sort of gray area, which is, if we understand that in the whole population, there's a sort of graded risk, right? So some people are at higher risk. Some people don't know a risk. We can now add that up and we can show that a person with a high risk school is likely to be about 12 kilos heavier by the time they age, reach age 18.

Then if someone with a low risk score. Okay. Just purely, just based on adding up the effects of about a million different genetic variants. Um, maybe if we were able to focus resources and attention on people who have a higher risk, might we be able to prevent some of the obesity related complications in that group?

That's a study that needs to be posted. But we don't know the answer to that, um, stuff, uh, correct me if I'm wrong, but the, um, the proportion of the population with genes that put the much increased risk likely hasn't changed over the last 30, 40 years, um, in, in the UK. And, um, what we've seen is people's biology, um, and their psychology just overwhelmed by these food environments.

And we haven't talked about the elephant in the room is who's winning, uh, out of all this, say the corporations, um, and, uh, as mentioned, you know, that they are well aware that they are producing foods that are very hard for us to resist and we've seen. Scholars now looking in more detail at a corporate interference in public policy at one extreme.

Um, we also see that we are in, um, uh, an apartment where, uh, the private sector is really important to our economy. And so I think that there's an important trade off between health and wealth, uh, and, uh, at the moment, health is not with. Say how we shift that? Um, say I think between us, the three of us we could sketch out was a healthy food and activity environment would look like, um, it would be radically different and staff wouldn't have been late arriving for this podcast

walk here. She would have been on her e-bike and there wouldn't have been any cars in the way that the policy, the air would have been clean. Um, and we'd all have eaten and drank different things for our breakfast. So I think that we're up against a really powerful force. Um, that, uh, if you like conspiring against our biology and our psychology, I really hate that there is shocking figures that were released last week on childhood obesity, really do, uh, empower and embolden politicians and policymakers to work more closely with academics in order to say, okay, uh, we really all gates go further and faster.

This. Um, I was going to ask if you don't mind, um, how each of you thinks about obesity from an individual perspective, by which, I mean, we've discussed ways in which things, to some extent out of our control, either our genes or our environment might affect whether or not we are obese or gain weight at any point in our lives.

But I think there's probably a lot of, um, negative emotions associated with the idea of being overweight. Certainly there could be for some people. How do you think about the idea of individual responsibility when it comes to your weight, in the context of the research that you do? I think, and, you know, we, we attempted to S to see things as black and white is either personal responsibility or not.

Uh, and I think, you know, it's quite clear that. Responsibility also then, you know, the challenge with responsibility is it leads to blame for people who have not been able to succeed, um, which leads to guilt, uh, which leads to stigma, which leads to discrimination and bias. And actually we know very well that people who encounter those kinds of sentiments, particularly from their healthcare professionals, are less likely to be successful at losing weight, uh, less likely to, um, maintain any weight they might lose and are more likely to have metabolic complications from their obesity.

So how we approach the issue and the advice that we give and the care that we give is actually really important and almost as important as what we're doing. So I think one of the fundamental things is how we use not only what policy changes and what health advice we give, but it's how we give it, uh, which is why there has been a focus in, in a number of places.

And we're beginning to see. There is some discussion on dealing with the UK government at the moment, um, about talking to people about healthy weight and maintaining a healthy weight versus correcting obesity. Um, now, you know, that's a slightly complicated one because there are medical issues that all have to be dealt with, but I think there is quite an important, um, area to understand, which is it's about how we communicate things.

And that has been a major, I think, uh, uh, uh, home that has been caused by policies in the past, or it basically, uh, it harms and it, it prevents engagement with the very people who may benefit. I think about it is the vast majority of people want to be healthy. They value, they value their health. Um, Most people, I want to have a, an enjoyable, healthy diet.

Um, and what we're all up against is environments that make it extremely difficult. Uh, some of my colleagues, I draw an analogy with, with driving. Uh, most of us, they want to drive recklessly and say, I we've got environments and rules around us that enable us all to drive safely. And so I think that's why all fakers, well, I'll, I'll focus.

My focus is driven by the evidence and I can see that in our current environment, unless you've got extraordinary resource, you live in an area of a high effort. Uh, it's extremely difficult to keep your, uh, your body weight within the normal range. Um, I, we know that 60 at the maintenance, 63% of adults in the UK are overweight or obese.

So our current environments make it normal to be overweight or obese. It's not that people want to be overweight or obese. So that's how I think about personal responsibility. And just to add to that, I mean, I agree with everything that staff interiors have said, but I would be, you know, happy for everybody to have the opportunity to live a healthy lifestyle.

You know, if that's the choice that they want to make. But just the reality is that at the moment, in many, many spheres, that is not the situation as it stands. And that's what we need to work to. So what's the takeaway when it comes to our weight and our well, so that said that the fact that I'll wait is strongly in some inspired genes can guide us in a number of ways.

For example, this knowledge can guide policy by injecting a more nuanced and accurate understanding of why some people gain weight more easily than others. Uh, policy which relies solely on personal responsibility is highly unlikely to be particularly successful when there is a strong biological or genetic driver underlying what we do, how we behave and how we interact with our environment.

This knowledge can also help guide the treatment of people with severe obesity, which is around a million people in the UK. These people are much more likely to benefit from treatment, which in some way recognizes the biological side to obesity. Simple changes in diet and exercise are unlikely to be effective in many of those individually.

Genetics can also tell us an individual's risk of obesity. Some people are at higher risk, some at a lower risk and a person with a higher risk score is going to be on average about 12 kilos heavier. By the time they reach age 18, if we were able to focus resources and attention on people who have a higher risk, we might be able to prevent some of the obesity related complications in this group.

Theresa said that the proportion of the UK population with genes that put them at increased risk of obesity has changed over the last 30 to 40. People's biology and the psychology is overwhelmed by newer food environments. Corporations are well aware that they are producing foods that are very hard for us to resist.

Once you pop you can't stop. Don't forget. And we've seen researchers now looking in more detail at corporate interference in public policy, the private sector is really important to our economy. So there's an important trade off between health and wealth at the moment. Health is not winning. How do we shift that?

Can we. Hard to say, we're up against powerful forces that are conspiring against our biology and psychology, like a case for model doing Scully. And we ended the discussion with the guest's view on the stigma around obesity and the idea of individual responsibility. So said, it's not just what health advice we give, but it's how we give it.

Apparently there are some ongoing discussions at the moment with the UK government about talking to people about maintaining a healthy weights, rather than the idea of correcting Theresa noted that people value their health and want an enjoyable, healthy diet that we all, but we're all up against environments that make this extremely difficult.

The room of bog Twix is again,

Your biological and technological distinctiveness will be added to our Twix, but we're all up against environments that make this extremely difficult. The room of bald Twix is again, your biological and technological distinctiveness will be added to our Twix. I had a great analogy with driving. Most of us don't want to drive recklessly.

So we've got environments or rules that help us all to drive safely, like speed bumps near a school. So why not create environments and rules that enable us to eat healthily? Unfortunately, our current environments make it normal to be overweight or obese. It's not that people want to be overweight or obese.

Tom concluded that the opportunities simply aren't there for everyone to live a healthy lifestyle. Instead, that's what we need to work towards. Well, it looks like we've reached the end of another episode. Stay tuned for our next episode on mental health before then please spread the mind over chatter word, who do you know whose life is simply incomplete without our voices.

And there is, and please fill out our survey to tell us what you think of the podcast. You can find the link to the survey in the episode description. We want it all the good, the bad and the ugly. Oh, and please make sure to leave us a review on whatever platform you use to listen to your podcasts. We like reviews, hopefully a good one, not a bad one or an ugly one.

A huge thanks once again to our guests. So Dafoe, Lukey, Teresa Moto, and Thomas goin, and finally a big thank you to the secondly talented Carlo lad for our music and the equally talented Alec Sadler for our artwork. TNA.