3 science-backed ways to shrink the belly fat linked to cancer and heart disease with Prof. Jimmy Bell

There's a hidden fat that matters more for your health than your weight.  This is visceral fat: it wraps around your organs, raises your risk of heart disease and cancer, and builds up even in people who look slim and healthy. 

Jimmy explores why two people can weigh exactly the same and carry completely different amounts of this hidden fat, what it is, where it hides and why it matters.

By the end, you'll have a completely new understanding of body fat, and what it really means for your long-term health.

If your weight has stayed exactly the same for years, what do you think is happening underneath it?

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Jonathan: Jimmy, if I manage to have very low levels of body fat, would I be healthier?

Jimmy: No.

Jonathan: If I have too much visceral fat in my belly, could it reduce my life expectancy?

Jimmy: Yes.

Jonathan: Can fat tissue in my body influence my mental health?

Jimmy: Yes.

Jonathan: Can more visceral fat increase the inflammation in my body?

Jimmy: Yes and no.

Jonathan: What is the most common myth that you hear about body fat?

Jimmy: That all fat in your body is bad. You just have to know how to treat it.

Jonathan: So I spent, you know, the first 35 years of my life being told I was thin, and that all changed when we did our first big study at ZOE of 1,000 twins, and I got to be a participant in this study. And as part of the study, I had a full body DEXA scan to measure my body fat and where it was distributed. And I will never forget this experience. So the nurse is doing this scan, and she actually stopped and double-checked the results, 'cause there I was, you know, on the table with very little visible fat on my arms, my legs, but it turns out that I had lots of fat wrapped around the organs in my belly, which is called visceral fat. And I was told that I was a TOFI, thin on the outside, fat on the inside, and that being a TOFI was going to be very bad for my health. And this was pretty scary and was probably the big aha moment for me personally that caused me to take my own diet seriously. And it's exciting for me, Jimmy, that you're here today because you're the scientist who invented this term TOFI as a result of your research into the biology of body fat. And it turns out that, you know, most of the things that I understood about fat were just wrong. So maybe we could start with why it matters where in the body you store fat for your health, and indeed, where is fat stored in your body?

Jimmy: Yeah. I think we should step back a bit and start talking about body fat, which is adipose tissue. And adipose tissue is an organ, so it has many components, and you have to think that those components that make up that organ have very distinct anatomical and metabolic characteristics. And it's very important where that fat is in relation to your health. So you can unpack adipose tissue into many fat depots. So the most common ones, you know, is the one which is outside your body, which is mainly subcutaneous adipose tissue, and then there's internal fat, like visceral fat.

Jonathan: Adipose tissue for me just means body fat. And so where are the normal places that this is stored in my body?

Jimmy: External part, which is called subcutaneous adipose tissue, and then internally, the main one being the visceral fat or visceral adipose tissue.

Jonathan: And so if you're gonna tell me where in my body or a listener's body fat is being stored on that external place, where does it mainly end up?

Jimmy: Anywhere between your neck and your toes, you're gonna find fat depots that are gonna have different metabolic effects. So you have fat around your heart, fat inside your liver, fat inside your pancreas, fat around your kidneys and inside the kidneys. You're gonna have things, fat around your prostate, fat streak in your muscle. You'll have fat around all your organs in the abdomen, which is called visceral fat. And each one has a slightly different risk assessment when it comes to cardiovascular problems.

Jonathan: You're talking now about the fat that's stored sort of inside my chest and torso. Is that where most of the fat in my body is stored?

Jimmy: No, most of your fat is stored externally, which tends to be metabolically less active than the internal fat. So you could think of your external fat as a buffer zone, especially if you carry around your hips and your thigh, and the internal fat be more metabolically active and more of a risk factor for conditions like type 2 diabetes, cardiovascular disease, cancer, and so forth.

Jonathan: I feel like men and women tend to store fat differently. Is that right?

Jimmy: We all store the fat in the same places. It's just the levels are different. So there's a hormonal genetic component to this. So men tend to deposit their fat more internally than women. If you look at two males and females and look at the identical BMI, you'll find that a male will have far more visceral fat than a female, but a female will have more external fat than the male.

Jonathan: Men are having it more, the visceral is what we're describing sort of all around my belly and there. Where do women tend to distribute their fat?

Jimmy: Externally around their hips and their bottom.

Jonathan: Okay, so this difference is sort of true?

Jimmy: Yeah. This whole thing about one minute on the lips, a lifetime on the hips is actually unfortunately true for females.

Jonathan: And for a man, you're saying it's a minute on the lips and then a lifetime around my belly?

Jimmy: Yeah.

Jonathan: And if you could choose where to store the fat to make sure that it was as healthy as possible, where would you put it?

Jimmy: I would become a sumo wrestler and have most of my fat externally.

Jonathan: Got it. And does it matter where it is externally in terms of the health impact?

Jimmy: Abdominally is less of a buffer zone than, say, your hip and your buttocks, so that's much more protective, while the central part can be, especially it depends on ethnicity and this ethnic issue as well, where the subcutaneous fat can be protective in terms of risk.

Jonathan: So I think what you're saying is that where women tend to lay down the fat, which is sort of hips, thighs, bum, that's actually healthier than where men tend to lay down their fat, which tends to be in this sort of visceral fat around the organs.

Jimmy: Yeah, nature was not very kind to men, I'm afraid.

Jonathan: Do we have any idea why men and women lay down fat differently?

Jimmy: That's interesting. There has been lots of speculation in there. One is hormonal, and you see that in menopause as the women go into menopause, they start getting more and more male fat distribution than a female fat distribution. It might be just a dynamic thing. So if you're a hunter-gatherer, people suppose that it's better to have your fat centrally so your center of gravity's always in the right place. And in the hips for women, it's because fat storage is basically at the end of the day, it's energy you're storing for long-term survival, maternity and so forth, then it makes sense from an evolutionary point of view. In a modern world, of course, it doesn't make sense at all.

Jonathan: So you're saying that as a woman, because I'm going to get pregnant and have a baby and need to breastfeed and things, like, I need to store this fat in the wilderness, 'cause I won't be able to go down to the supermarket and get some food?

Jimmy: Yeah.

Jonathan: I just wanna follow up on something else you said, which is that as you go through menopause, your fat distribution shifts and becomes more like the male fat distribution. What would that mean in terms of where my fat was before and where it ends up going afterwards?

Jimmy: For women, it means they'll start getting more central fat, so away from the hips and more around the visceral area, around the organs, and around the abdomen.

Jonathan: And so that could happen even if your weight was fairly stable?

Jimmy: Stable, yes.

Jonathan: It's actually like a redistribution of what's going on.

Jimmy: Yeah, absolutely. What we're finding is that people who keep stable weight, keep the fat and are losing the muscle. So their weight stays the same, but the ratio between fat and muscle gets worse and worse and worse.

Jonathan: And so that's also true for everybody as we get older? Even if your weight is stable, potentially you're losing muscle and gaining fat. And you're also, as a woman, seeing this fat distribution shift from somewhere that you said was really healthy to somewhere that is less healthy. I asked the question about the healthiest place to put the fat. What are the worst places to store it?

Jimmy: So in a pecking order, if you like a pecking order, I would start visceral fat, then liver fat, pancreas fat, and then what we call IMAT, which is the Intermuscular fat. So that's the fat that streaks across your muscle. All these fats are independently risk factors for type 2 diabetes, cardiovascular disease, cardiometabolic diseases. But the main two culprits at the moment are seen as visceral fat and liver, which are interlinked. There is an axis between visceral fat, pancreatic fat, and liver fat, and lately it's become very clear that the amount of fat that you deposit in your muscle can be very, very detrimental, especially as you grow older.

Jonathan: When you started to differentiate between visceral fat and liver fat, I'm like, you know what, I'm a bit vague really about what's really going on inside my body. Could you help me to understand a bit more what visceral fat therefore means?

Jimmy: Yeah. We call visceral fat in general, it's a fat inside your body around the organs in your abdomen, anywhere from the top of your liver down to your hips. Anything inside is generally called abdominal fat or visceral fat.

Jonathan: Got it. And so I think historically I've tended to think about belly fat as being an aesthetic issue, but actually that belly fat which we think about as being aesthetic, you know, your research is saying that this really matters about health.

Jimmy: Yes.

Jonathan: So can we go back to that term TOFI that I learned about during my own scan, 'cause I had never heard of it before. What does it mean and why is it possible that you can look thin on the outside but be fat on the inside?

Jimmy: So initially we used to do measurements of body composition indirectly. So we use a tape measure, we have calipers to measure the thickness of fat. We take the underwater weight, and so you put someone in a swimming pool and see how much they displace and work out density and so forth. When imaging came along, especially CT and MRI, we realized that we can start looking inside people's bodies and we discovered, and this is with one of our colleagues, Gary Frost at Imperial College, who said, "Look, I got people with identical BMI, identical body composition by all these measurements, but the insulin sensitivity is completely different." What happens if you scan them? And we scanned them, and one of them has no internal fat. The other one had lots of internal fat. I said, "That's it, your answer."

Jonathan: They look the same on the outside.

Jimmy: Yeah, absolutely. They had the same BMI, same age, same ethnicity. Everything was the same.

Jonathan: And BMI is basically sort of their weight compared to their height. It's like a traditional measure of whether you're thin or fat. And so they look exactly the same. They're the same on all of these traditional medical ways to judge your health.

Jimmy: But metabolically, they were different.

Jonathan: And you were saying one of them was really not in good shape metabolically?

Jimmy: Yeah, and the other one was. It made no sense. So when we scanned them, one had lots of internal fat. And then we started looking at this, "Oh yeah, this is happening." And then we started seeing that there was a small percentage, including myself, that actually we had the normal, healthy BMI, but the amount of fat internally was disproportionate to the amount of external fat. We used to have this very long word to describe it, but someone came out with TOFI. It was one of the reporters who actually said, "Oh, you mean thin outside, fat inside." We went, "Oh, yeah, okay. Yes."

Jonathan: Well, you get all the credit for it now, Jimmy.

Jimmy: So it's, yeah, yeah. I know, but I have to give credit to people. Scientists are not very good at transmitting our findings.

Jonathan: And do we have any idea why it is that you could end up as this TOFI?

Jimmy: I think it's mainly because of lifestyle choices. At the time, there was a lot of emphasis on diet and for a long time being just diet and maintain your weight, and it was all about weight. Not the quality of the weight, just the weight. So if you tend to maintain your weight mainly through dieting, you end up having the wrong body composition because as you put weight on, you put a disproportionate amount of fat on with very little muscle. Yeah. So your ratio of fat to muscle gets more and more detrimental, and this is why you end up with a situation where you might maintain the right weight but the wrong composition. This does not happen if you maintain your weight with exercise.

Jonathan: The thing that to me seems most surprising is I've always thought about fat as it's just a way to store calories for later use. You know, like a bear getting ready for hibernation. You know, it's eating all the salmon, it gets really fat, it goes away and, like, hides in a cave, and slowly it depletes the fat. That's the only thing it does. So it's like a completely dormant way to store energy. Is that correct?

Jimmy: That was the thought until about 20, 30 years ago. This was all changed when they discovered that adipose tissue creates molecules, one of them, the most famous being leptin, that affect your appetite. And bit by bit, people transfer the adipose tissue from a tissue, which is very passive, to an organ, which is a very active component of your body. And now adipose tissue is your friend that tells you about the outside and it tells you about the inside of your body. Externally, it's telling you about food and energy availability. Internally, it's telling you about moods, about your biological status and so forth. That's why people who tend to be large tend to be happier, yeah? Because it's that balance that you have to find between having enough energy without creating metabolic problems. You could think of adipose tissue as a brain and it's actually all the time aware of what is happening to your body, internally in terms of energy, in terms of inflammation, in terms of all the processes happening inside your body. Yeah. And it's responding to that. If the energy is too low internally, let's release fat. It's too much, I'll store some. There is inflammation, I will release some chemicals. If there's too little, I would release the right energy so those chemicals can be produced. And at the same time, it's very aware of the outside. If there is no food, let's store it very quickly because we might need it in the long term. So, you know, it's protecting you from bumping into things and if it's too cold or if it's too hot. So it's a very dynamic system. It's a friend that might love you a bit too much when you love it too much.

Jonathan: That's a bit the way that I feel about ice cream. You said something about how it could affect your mood. Could you help me to understand that? And something to do with being happy.

Jimmy: Yeah, so one, adipose tissue affects your appetite, but also the inflammatory markers and inflammatory chemicals that the adipose tissue is actually reacting to, and that inflammation affects your brain function. These have been shown already. So when you put weight on and you become obese, you get subclinical inflammation. So it's not inflammation where you're getting arthritis, but just much lower. Yeah. And that is affecting your mood. So it's like if you receive an injury, if an animal is injured, you get a massive inflammatory response to repair that injury. Yeah. And animals go and sit in a corner until they get better. When you become obese, you don't get that kind of massive inflammatory process, but much lower. So you still feel that you're injured, but you're not quite injured.

Jonathan: It's all the fat in your body is actually sending out these inflammation markers?

Jimmy: Especially your visceral fat and subcutaneous fat, but the visceral fat is quite central. So when you get a combination between inflammation and visceral fat, that is a very bad combination.

Jonathan: So this visceral fat around my belly, if I've got lots of that, it's not just sitting there doing nothing. It's actually sending out inflammatory signals to the rest of my body, and if I've got a lot of it, it's like sort of always on pumping out this inflammation. And on top of that...

Jimmy: The inflammatory cells come to the visceral fat and makes it even more excited, so it becomes a vicious circle.

Jonathan: So also, if I have other inflammation, which I might well do in our modern world, how do your fat cells respond if that inflammation is going on?

Jimmy: The mechanisms are not clear at the moment, but clearly they start pumping out more inflammatory signals, so it becomes a vicious circle which attracts more inflammatory cells.

Jonathan: So my inflammation is up, and then if I have a bunch of this visceral fat, it then pushes out more inflammation, and then the rest of my body goes, "Oh, the inflammation is worse," and it's a vicious circle.

Jimmy: Circle, and it tells you, "Go and sit in the corner until you get better." But of course, you're not gonna get better because you're obese.

Jonathan: So talk to me about the sitting in the corner. How does this tie to my mood that you were describing?

Jimmy: If an animal's injured, yeah, you'll see they become very passive, or they sit down in the corner until that injury gets resolved. And what are the signals to tell it to calm down and sit in the corner and just kind of, you know... It's the inflammatory signals. But when you become obese, you got the inflammatory signals without the injury. So your body's telling you, "Look, there's inflammation. You should be more passive, and it will resolve this problem." But that problem is not gonna resolve because you're not curing an injury or a wound. You just got these subclinical levels of inflammation that are affecting the way you're gonna behave.

Jonathan: How will this make me feel?

Jimmy: Less likely to become active. It's a very open question at the moment, is the whole area of how moods and behaviors are affected by adipose tissue, but it definitely is affected.

Jonathan: One of the things we see a lot through the gut health research we do at ZOE is the way in which improving your gut health has this really positive impact on mood and energy, and very dramatic and quite fast. Are these a similar sort of self-reported feelings that you would associate with this sort of excess of visceral fat?

Jimmy: Yeah, absolutely. And if you resolve that, you resolve the problem. So you resolve the problem of having too much visceral fat and having it inflamed, yeah, you will resolve lots of the problems at the same time. But the body's telling you, "Don't do anything until we resolve the problem." But the problem is the problem itself, if that makes sense.

Jonathan: It does make sense. So it sounds pretty clear you don't want to have too much visceral fat and I guess not too much fat overall. Wouldn't I be better off in today's world having almost no body fat? Because after all, I can always go to the supermarket and buy more food, so I don't need to have it stored in the same way that our ancestors did. So shouldn't I be aiming for almost no body fat?

Jimmy: If you think of body fat simply as a dumping ground for excess energy, but we already established this, it is an organ, it has other functions. It has function in fertility, has function in your moods, the way your immune system works. So if you don't have any adipose tissue, there is a condition called lipodystrophy, a genetic condition where people have almost no fat because of genetic reasons. They end up having type 2 diabetes. So you end up with having no fat and all the problems of obesity.

Jonathan: Oh, so you can have so little fat that it's really unhealthy.

Jimmy: Because the fat has to go. There's fat in your diet. You can't get away from fat, okay? It's everything you eat has a small amount of fat in it, large or a small amount of fat. That has to be stored somewhere. So if you don't have adipose tissue, it will be stored inside your liver, inside your pancreas, inside your muscle, in all the wrong places, the worst places that you can think of. So that's why adipose tissue's your friend, yeah. It says, "Okay, I'll store away that excess in a good place." But if you do overdo it, I have to put it somewhere.

Jonathan: And in your view, Jimmy, 'cause this is your area of research, do you feel that this adipose tissue, this storage of fat, is it doing any positive things for us now that we understand it's more like an organ that's active, or is it only sort of a risk of danger if it's in the wrong place or there's too much?

Jimmy: Everything that the fat does is good. One, store energy, maintain your immune system. So if you get an infection, adipose tissue is there working for you to stop that. If you get wounded, adipose tissue's there giving you the chemicals to repair the wound. It's keeping you warm. It's keeping your mood up. You know, it's doing lots of good things.

Jonathan: I'm thinking about these sumo wrestlers and supermodels at the other end. Supermodels are obviously famous for having almost no body fat.

Jimmy: No, no, no. They're famous for being very thin.

Jonathan: Okay.

Jimmy: Nobody has done a really full study of their body composition. We tried to do this, and unfortunately I made a mistake of telling them what I was trying to show, that their body composition was not healthy. You see, models, as far as I understand, not that I know any supermodels, they are not allowed to have any muscle delineation. Therefore, they are not allowed to actually exercise because otherwise you can see. They have to be smooth. Oh, the stupidity of the industry. The only way you can achieve that is through dieting. And when you lose weight, you lose muscle as well. So in the supermodel, we got no idea what their body composition is.

Jonathan: But what is your guess?

Jimmy: My guess is that it's not very healthy.

Jonathan: So your guess is they do have fat, but only sort of this visceral fat around their organs.

Jimmy: Yeah, and probably in their liver as well. The two models that we managed to scan, they did not have very healthy body composition. They had too much fat in their body, even though they look very thin.

Jonathan: And how does that compare with a sumo wrestler? They seem like the definition of incredibly unhealthy 'cause they've got this enormous amount of fat folding over them. So I would assume that they are vastly less healthy than a supermodel.

Jimmy: I follow sumo wrestling, but they do six to eight hours of exercise, and in Japan, through decades or hundreds of years of trial and error, they came out with a regime that they accumulate fat, but most of the fat is accumulated externally. So you see them really large. When they have done CT scans of sumo wrestlers, the amount of visceral fat is very low, extremely low, surprisingly low.

Jonathan: And so there have been scans of... And so potentially a supermodel might have more visceral fat than a sumo wrestler?

Jimmy: Could be. We're talking about Japanese sumo wrestlers, because there are lots of Western sumo wrestlers that don't follow the same regime, and they're very large, and those people are not exactly what I would call a sumo wrestler. If you look at a sumo wrestler in detail, they got huge thighs. Huge thighs means lots of muscle, good quality muscle, and that's another important thing.

Jonathan: So why is it that we accumulate fat around our organs if it's so unhealthy? Because you'd think our body would know that and wouldn't lay down fat in these bad places when it's got perfectly good places. I'm looking at my legs and my arms and thinking, you know, my butt. Why can't it put the fat there?

Jimmy: Okay, so imagine you are designing a system and you think, "Okay, I got two functions that I have to do. One, store excess energy." And you say, "Okay, I'll put it outside, because when I need it, it's a slow process. I put it outside. It will also protect me from the cold or bumping around into things and whatever." Then I need another dynamic system where I need it for my inflammatory responses, infections. Most people a thousand years ago used to die from infections. Well, your visceral fat, is quite key for inflammatory responses to infections. So that's why you put it there. Yeah? Of course, in the modern world, you just take antibiotics and that's that.

Jonathan: So you would put some fat inside your organs in order to support your immune system really fast. Around the organ. So it's actually literally to support something like the inflammatory processes that you need for infections.

Jimmy: The inflammatory processes that you need for infections and...

Jonathan: So there's a bit that's around these organs that I can get to very fast to support my immune system to fight some sort of infection.

Jimmy: Your visceral fat is metabolically very dynamic, so it responds very quickly in comparison to your subcutaneous fat.

Jonathan: And what does respond quickly mean?

Jimmy: In terms that it doesn't have to have lots of signals. It responds immediately. So if there's an infection, inflammatory cells require fat, require signals. It responds immediately.

Jonathan: So it's sort of like I can access it very, very fast, is that what you're saying? So there's visceral fat, in theory, I can pull out really fast.

Jimmy: Yeah. But your subcutaneous fat doesn't.

Jonathan: So that takes time to pull down.

Jimmy: Especially if you are around your hip. It takes even longer to respond.

Jonathan: And so the idea is I'm storing that, this is sort of like my immediately available petrol tank for this. But your expectation is just sort of run that down quite fast, which I guess these days that's not what happens, and it just sits there for years slowly growing?

Jimmy: Yeah, but it's very responsive, because if you do diet, one of the fat deposits that decreases the most is the visceral fat, because it's very responsive. The same with exercise. The same with liver fat. So they all have their reasons. It's just too much is a problem. Too much with inflammation on top of that is a bigger problem. Then the composition of the fat is also important.

Jonathan: What do you mean by that?

Jimmy: So whether it's saturated fat or unsaturated fat, that in itself is a risk factor.

Jonathan: So our body can lay down different types of fats?

Jimmy: Absolutely, yes.

Jonathan: Could you explain that to us?

Jimmy: So, well, it reflects very much your diet. So if you eat lots of saturated fat, you know, if you go to McDonald's and eat lots of fatty foods with saturated fat, that's what your body's gonna look like. We can measure the amount of saturated fat or unsaturated fat. You want to have as much unsaturated fat as possible. So if you look at vegans, who tend to eat a healthier diet with lots of unsaturated fat, even though the amount of fat is the same, the composition of the fat is different.

Jonathan: And is it the composition that's more important?

Jimmy: No, no. It's the amount, the distribution, and the composition.

Jonathan: Got it. But what you're saying, let me just understand that. If I eat lots and lots of red meat, then actually slowly my body sort of resembles the kebab or the burgers that I eat. But on the other hand, if I am eating lots of avocados, then actually the fat, I look more like an avocado inside me.

Jimmy: Exactly. Well, all your fat. Not only inside, all your fat.

Jonathan: All my fat. So your body actually reflects the type of fats.

Jimmy: Even the fat in the bone marrow, it reflects your diet, and that is a risk factor in itself, so it compounds. So if you have visceral fat that is very saturated, it's worse than having visceral fat that is unsaturated.

Jonathan: So eating a really fatty piece of meat is likely to be worse than a lean piece of meat because I'm just gonna take that fat from the cow or whatever, and my body's like, "Great, that's what we're gonna be laying down around your liver tomorrow."

Jimmy: Yeah. If you have olive oil and the same amount of sunflower oil, then the olive oil is gonna be much better because that's what is gonna reflect in your body. And when the immune response occurs, the immune response needs lots of polyunsaturated fat. It doesn't need the saturated fat. That's the first thing that gets moved by the body is the unsaturated fat, because it's essential for the immune response. And if you got trans fat, that's even worse because you can't move it at all. So you can see the complexity of this organ.

Jonathan: So let's say someone is listening to this and they're like, "You know, I've been thinking about changing my diet for a long time. I know I'm eating way too much red meat and bacon, and all these sorts of things, and I wanna switch towards a ZOE style diet that's much higher in plants and healthier fats. Will the fat in my body turn over? Is it all too late?" And how long does it take?

Jimmy: No, no, no. So a Swedish group from the Karolinska Institute did a beautiful study and where they showed and they measured the turnover of adipose tissue, and it takes between two and three years to turn over your adipose tissue. So your fat will take between two and three years. So if you change your diet now, it sounds depressing, but it's not, that it'll take you about two to three years to change from a saturated meat-looking person to an unsaturated avocado-looking person. In biology, everything takes time. You know, I always sort of say, "Nobody goes to bed thin and wakes up in the morning overweight." Okay? It's a long process. Your body didn't become saturated overnight. It's a long process.

Jonathan: There's almost like two benefits here it sounds like. One is you're gonna lose the visceral fat and that's gonna be healthier for you. Is that correct?

Jimmy: That's right.

Jonathan: But then the second thing is you actually would like to change the composition of your visceral fat. So it's not just the amount. There was this amazing study published a couple of years ago looking at improvements in years of life if you switch from the standard poor quality diet in America or the UK to sort of a high quality diet. And the thing that stuck in my mind the most is you could be 70 years old and you could switch to a high quality diet and you could live for another six or seven years, which is sort of crazy. But now listening to this, is this the sort of thing that can explain that? Because you're actually, after a year or two, your whole body fat is turned over to something much healthier.

Jimmy: Yeah, absolutely, yes. This is a part of this. When people lose weight through dieting, if that's what they're gonna do, it's not what I recommend, but they should not only reduce the amount of calories they take in, but also the type of calories, because you get double benefit. Yeah. You lose the weight and you change the composition of the adipose tissue, which will help dampen down your inflammatory responses. It will improve your inflammatory responses. And with that, there are many things. You know, inflammation is a massive thing, beyond my own expertise, but something quite important to keep an eye on.

Jonathan: There's obviously an enormous interest in weight loss drugs at the moment and sort of dieting and yo-yo dieting. If I start taking these GLP-1 drugs like Ozempic or Wegovy, do we know what that does to our visceral fat as opposed to we know it reduces our overall fat?

Jimmy: I find GLP-1 agonists an amazing drug. I mean, they work. You know, they don't work for everyone, and the mechanism is still unclear at least for me, but they work very effectively. So the discussion then became, what sort of weight do you lose? If you diet and you take GLP-1, do you end up with the same body composition at the end? And this is the big open question. So visceral fat drops, because if you lose weight in any form, visceral fat, liver fat, drop. They're the first fat depots that you're gonna see dropping. Second, the quality of your muscle, in the sense that how much fat you have streaking across your muscle, also decreases, which is also a positive thing. And we haven't spoken about the value of having lots of muscle and the quality of muscle. So it's not only the amount of muscle, but the quality of that muscle. Now, there is a discussion as to how much muscle you lose when you diet. So if you do diet alone, you decrease, say, your intake of calories by 50%. You lose fat, but you also lose muscle. Yeah? So you don't end up in a good place if you don't do any exercise. In the GLP-1 agonist treatment, we don't know how much muscle people are losing. The literature's quite contradictory, but there hasn't been a proper study, at least published study. It might be that the pharma companies are doing these studies, I don't know. Again, I'm not privy to that. But we don't know how much muscle and the quality of the muscle they are losing. And this is worrying because if there is an excess of muscle being lost, not only fat, but excess of muscle in comparison to how much fat you're losing. So if you are losing the wrong amount of muscle and the wrong type of muscle, you might be creating in future a pandemic of sarcopenia and all related conditions.

Jonathan: And so this is back to a little bit your supermodel conversation, isn't it? Where I've clearly lost weight on the outside. Potentially on the inside, I've still got these pools of fat in these really dangerous places. There's visceral fat, and I've just lost a lot of muscle that I don't see. So we might look at someone and say, "Hey, you look great," but actually, you know, if I had the scan in my eyes I'd see, oh, you've lost a lot of muscle, and so you need to do something around that at the same time as you're losing weight.

Jimmy: Yeah, absolutely. To be fair to them, which I'm never fair to a pharma company, but I will be fair to them, they do say that people that take GLP-1 should include exercise as part of their lifestyle recommendation, and I think this is important. And this is important in any way that you lose weight.

Jonathan: I was going to ask, actually, Jimmy, what about people who have been doing this sort of yo-yo dieting in the past, which is incredibly common? In fact, it's been promoted really by our culture. So you know, you do a crash diet, you lose some weight, you put it back on, you do a crash diet, and repeat it. What does that do to my visceral fat and my body composition?

Jimmy: Well, what it does is and I think that's why I want to bring skeletal muscle into the conversation because muscle can work as a counter to some of the problems the adipose tissue entails. So when people diet, they lose fat, but they also lose muscle. So the ratio of fat to muscle becomes worse. When you put weight on, that ratio becomes even worse. So you have too much fat, very little muscle. You lose weight again, that ratio gets even worse. So as you yo-yo, your fat to muscle ratio becomes worse and worse and worse. So the recommendation should be that if you lose weight in any form or shape, you should do exercise because you lose weight, but you put back that muscle. So you might end up with the same weight that you want to achieve, but the composition will be the proper composition.

Jonathan: The muscle is actively beneficial?

Jimmy: The muscle is absorbing lots of the sugars. You know, it's metabolizing it. Beside the mechanical need for walking and so forth, especially as you are older, it also sends signals to the rest of the body. So the muscle now is producing lots of signals, and we detect the signals that change the metabolism around your body. So when you exercise, you're not only just burning fat and growing muscle, but you're sending signals around that change your mood, change your immune response, change your metabolism. But it's not only the amount of muscle, but it's the quality of that muscle. So you can have lots of muscle, but with lots of fat infiltration, that's not good muscle.

Jonathan: And what I'm taking away from this conversation is that, you know, if you're someone who's been a yo-yo dieter in the past, if we were gonna go and sort of do that scan between you and maybe, you know, how you might have been 10 years before, even if you had the same weight, actually, you're gonna probably have more visceral fat and overall you're gonna have more fat and less muscle, than someone who's never been through these cycles of weight loss and weight gain and weight loss and weight gain.

Jimmy: Yeah. People who maintain their weight through diet throughout their life, their body composition is getting worse and worse even though their body weight stays the same.

Jonathan: So I'd love to move now to, okay, what can you do about this? How can I reduce my visceral fat? But I'm also thinking that, you know, I got this scan that actually told me, wow, you've really got this visceral fat, but most people have never had a scan like that. So if someone starts by saying, "Well, I wanna know how much of a problem this is," you know, is, for example, measuring their BMI a good way to start to figure this out?

Jimmy: Yes and no. So if you're overweight and obese, it's highly likely, and you don't do any physical activity as such or exercise, it's highly likely you got very high levels of visceral fat, liver fat, pancreas fat, and lots of fat in your muscle.

Jonathan: And what about the reverse? Let's say you're listening to this and, you know, the doctors haven't been telling you that you're overweight, but now they're listening to this and thinking, "Oh, well, actually, maybe I do have the visceral fat," which was absolutely my situation a few years ago. Is there any way, from your own lifestyle or anything else that you could...

Jimmy: So, okay, so if you have a large BMI, it's almost guaranteed that you have lots of visceral liver and pancreatic fat and muscle fat. If you're thin, normal BMI, there's no guarantee that you don't have lots of visceral fat, liver fat, pancreas fat, and muscle fat. Now, if you're thin and your lifestyle includes a balanced diet and significant amount of physical activity, it's highly likely that you have the right levels of fat distributed around your body. So that's almost guaranteed. If you maintain your weight through dieting alone, it's highly likely you got lots of visceral fat and liver fat. I almost can guarantee it.

Jonathan: Let's talk about what you can do about it. Let's say you're listening to this and you're like, "I'm worried about the visceral fat. I want to reduce it." Other than medication to reduce your weight, we talked about GLP-1s, you said that will reduce your visceral fat along with everything else. What can people do?

Jimmy: I'm not gonna comment about diet. I'm not an expert on diet, but clearly there is lots of advice on dietary intake, amount energy. But I think if you're overweight and you go into a dietary regime of reduced calorie intake, improve the quality of that diet or that energy you're taking and add exercise. So the weight loss will lead to a reduction of visceral fat and liver fat and so forth. If you have stable weight, diets will have very little impact on the amount of visceral fat. It will come down to physical activity. Go to a gym to build your muscles. So resistance exercise appears to be a very important component of this, and you have to get out of breath when you do physical activity to start burning that fat because when the body starts burning that excess fat, the first areas that it will go to pick up that fat to burn it will be in the liver, will be in the visceral area, will be in the pancreas. And we and other groups have shown this over and over again. And long walks, not just talking to your friend, which is good. But you have to get out of breath, walk fast. So the speed becomes actually quite important. Yeah. And it was shown that if you get out of breath when you're walking, I'm not talking about trotting and I'm not talking about running. I'm talking just taking that pace up a bit. That you'll get all the benefits of walking and more.

Jonathan: So what you're saying is that when I start to do exercise at a certain level of intensity, then it's like pulling this visceral fat out?

Jimmy: Yeah, it's pulling... You need energy. When you do exercise, you need energy. You have to take it from somewhere. And the first place after the sugar will be the fat, and the first place it will come out will be the visceral fat and the liver fat, all the bad depots, because it's a very mobile, metabolically very active depot. And when you exercise, your process doesn't stop when you stop exercising. The effects carry on for hours, you know, days. And this has shown that your metabolism changes days after. This is not the work that we have done, by other people who have actually shown that the metabolism is altered very quickly. What exercise would I do would be resistance exercise because, two, you're not only burning fat, but you're building muscle. And again, we mustn't look at fat in isolation. Yeah. It's part of a bigger system, and there's a counterpoint which is called skeletal muscle. So if you build good quality muscle, it will counter some of the detrimental parts of the other fat, and we see this in the sumo wrestlers. So if you have to do some exercise, resistance exercise will be, especially as you're older, 'cause you're building muscle. Aerobic exercise, it will give you other benefits, you know, respiration and the way you breathe and so forth. You'll feel fitter, and it'll give you a high.

Jonathan: Can I ask about now about the sort of nutrition exercise trade-off? 'Cause I think that, you know, many people that I meet talk about, you know, any form of weight loss as being sort of 80% your diet and 20% your exercise, and that despite all the discussions about exercise driving weight loss, the evidence says that isn't really true. It's great for your health, but it doesn't lead to that. It sounds like, though, when you're talking about the visceral fat and the impact on my health, that you're weighting the exercise much more?

Jimmy: People are obsessed with weight, yeah. They're not obsessed with health, and this is a problem. And we did a study where we had 20 or 30 women, and we put them through lots of exercise and diet as well. And metabolically, they all became really healthy, and body composition, they all became very healthy. They all complained that they still look the same. If you want to lose weight really quickly, diet, and you're gonna end up with the weight that you require. Are you gonna be healthier? Yes, that in comparison to where you started from, if you were overweight or obese. Of course you're gonna be healthier. But if you diet and you did exercise at the same time, you're gonna end up with the same weight and a much healthier profile, and this is the thing. So it's not exercise and it's not diet, it's a balance between the two. So you cannot eat yourself out of a gym, but you cannot exercise yourself out of a bad diet.

Jonathan: So I'm thinking now about food, and I think we've already talked quite a bit about how the type of fats in your diet really affect the type of fat in your body, and that has its impact on your health. In a similar way that you're saying we avoid this sort of unhealthy saturated fat from certain sources. Is there anything else that we should be sort of avoiding in particular that is directly sort of linked to this visceral fat buildup?

Jimmy: I think the big umbrella that covers the whole thing is inflammation and your immune system. So a diet that will lead to an increase in inflammation or inflammation response, then that's a really bad combination if you got lots of visceral fat. These are two brothers that get together, and they just mess around with your metabolism.

Jonathan: So like I'm eating food that increases my inflammation.

Jimmy: That will trigger the visceral fat to be inflamed. It responds and says, "Oh, we're inflamed. Okay, let's all get inflamed." And then, "Yeah, you're inflamed. I'm inflamed. Let's all get inflamed." And it becomes a vicious circle that you want to avoid. So by having the right amount and the right composition of visceral fat, but then a diet that doesn't trigger further inflammation, it becomes important. So it's not only about the composition, so there are things...

Jonathan: What about alcohol? In my mind, this sort of beer belly, you know, I have this sort of direct link between particularly beer and having this sort of massive visceral fat. Is there anything in this?

Jimmy: Yes. Any amount of alcohol is bad for you. That's it. I know that the French say that if they drink red wine, there has been this correlation and so forth, but it's not the alcohol per se, it's all the components. You could take those components without having to have the red wine to get the benefit. In moderate amounts, alcohol, it's not bad for you. I mean, it's not terrible. Okay? So moderation, the Chinese have been saying this for about 10,000 years. Everything in moderation will be okay. Alcohol in moderation. People don't drink alcohol in moderation. Yeah? So you got the energy intake and then the alcohol has a detrimental effect, especially in your liver, increases inflammation. We are back to inflammation and the whole process of subclinical level inflammation and so forth.

Jonathan: So in your view, the alcohol, it's not just the calories in the beer.

Jimmy: No, no.

Jonathan: The alcohol is having an effect that leads to more of this visceral fat.

Jimmy: Yeah, because you already have a problem and then you hit it with another problem that triggers a massive response. So if you're very healthy and you drink a bit of alcohol, that's fine, but most people who drink alcohol, they're already unhealthy. Too much visceral fat, too much fat in their liver, too many toxins in their bodies, and then on top of that, they hit them with alcohol. The alcohol is creating damage in your liver and other organs. That triggers lots of free radicals. It's aging you faster.

Jonathan: So if someone's been listening to this and they found the whole story really compelling, Jimmy, and so they start to eat better, they start to exercise more, just as you're describing, how quickly can they lose this visceral fat that you're talking about that has, you know, so much detrimental impact on their health?

Jimmy: We have done interventional studies where we've shown within 12 weeks you can see a significant change in liver fat, visceral fat, pancreas fat.

Jonathan: Within 12 weeks?

Jimmy: Yeah.

Jonathan: And that's not some totally crazy crash diet?

Jimmy: No, no. It was a significant reduction of calorie intake and the quality taken.

Jonathan: This is in 12 weeks you can have a significant improvement in your visceral fat.

Jimmy: Yeah.

Jonathan: Which is actually a very short period of time that you're saying, and that would have really meaningful improvements in your health?

Jimmy: In your metabolic profile, absolutely.

Jonathan: Amazing. Final question, Jimmy. If someone was listening to this and they want to improve their long-term health, what's the one thing that you would recommend they start doing today out of the many things we've talked about? What would be the most important thing you'd suggest they should do?

Jimmy: It depends on the starting point. So I would say look at your diet and look at your resistance exercise. If you just include that in your day-to-day, control the quality of your diet, you can have a massive impact both on the composition of your body and the quality of the body.

Jonathan: Jimmy, I think that's really clear. I'd like to try and do a quick summary. The thing that really sticks in my head right now is this image of sort of the supermodels on one side and the sumo wrestlers on the other. And it seems really obvious that, you know, the supermodels have no fat, but actually if the supermodels don't do any exercise, if you were to scan them and understand their visceral fat, this fat around their bellies, you could actually find that the supermodels are worse than the sumo wrestlers, which I find extraordinary. And that's a problem because this visceral fat is really important for your health. And fat isn't just this sort of store of energy that has no impact on our body. Yes. We now understand it's this sort of organ which responds to inflammation in our body by then producing more inflammation if that happens, which can then lead to more fat. And that's particularly true if it's your visceral fat around your organs. It's all much more active. And so given that we live in this environment where in general we have this high sort of background level of inflammation, you then have this fat and you're in a sort of vicious spiral, which is why having lots of visceral fat is really bad for your long-term health. If you're listening to this and you're a man, then you're already, you've sort of drawn the short straw because you're naturally putting much more fat into visceral fat than women do who tend to put it into their hips and their bums. That changes for women as they go through perimenopause and because of those changes in hormones, it's just a fact that even if they're keeping their weight the same, it's going to redistribute towards their belly and towards the visceral fat. And so although you're eating in just the same way and you're doing the same things, your body is changing and, you know, that's just a reality of this hormonal change. But it matters because putting on that visceral fat is bad for your health. The other thing that I'm really struck by is this idea that if I eat McDonald's, my fat is basically McDonald's. If I'm eating avocado, then all the fat in my body is basically avocado fat. And that's really crazy because you literally are what you eat is what you're saying, Jimmy. The bad news is that's not gonna change instantly, but the good news is you can change it. You're not stuck with it for the rest of your life. So even if you just keep your fat levels constant, after two to three years of eating a healthier diet, you could have turned over and replaced all of that unhealthy fat with the healthy fat. And I guess this also talks to the fact that you can get a lot of benefits from a healthy diet fast, but if you can sustain that for two or three years, then you start to get this amazing benefit. And if we talk about certain fats like the fats in red meat as being unhealthy, that's also true inside my body. So if my visceral fat is all saturated fat, which is as a result of what I'm eating, then actually that's bad for my health. If I start eating olive oil and avocados and things like that, I could replace that visceral fat now with avocado and olive oil fat. That's actually gonna be healthier for me.

Jimmy: Yeah. I do want to emphasize a point that adipose tissue, this organ is made of lots of components, and liver fat and pancreas fat and muscle fat are as important as visceral fat when it comes to health. But they all get affected the same way when you do interventions.

Jonathan: Yeah. So let's talk about the intervention. So the intervention you don't want to do is yo-yo dieting because although you'll lose some weight, then when you bounce back, actually what happens is you've lost muscle and you put on more fat. And so if you keep doing yo-yo dieting, you actually end up with much worse body composition. And similarly, as you think about these GLP-1s, you will lose visceral fat as you lose weight, but if you bounce back, you're gonna be in a worse place. And even as you've come down, you've probably lost muscle, so you've really got to be aware of that. On the positive side, the thing that can really make a difference here, beyond the food that you eat, is physical activity. And all exercise is good. You talked about the fact, you know, if you don't go for a walk, go for a walk. If you go for a walk now so to the point that you're a bit breathless as you do it, this is gonna be great for your visceral fat because actually all exercise is gonna burn some fat and your body's gonna sort of pull out the visceral fat first 'cause it's easy to get to. That's exciting. But if there's one key message from all of this, it's do resistance training. That is the thing that is going to target that sort of visceral fat the best, and with this benefit that it builds these muscles that then has all of this sort of counteraction against the fat. And in your studies, you said in 12 weeks' time, using this combination of improved diet and resistance training, you can have a significant reduction in this visceral fat, and therefore an improvement in real measures of health.

Jimmy: Yeah. And just think fat is your friend.