Instant Genius - How to keep your body younger for longer

Episode Date: June 21, 2026

When it comes to the effects of ageing on our bodies, there are many more factors at play than simply the number of years we’ve been alive. It turns out, that for some people, there is a huge gap between their chronological age and their biological age – the scientific measure of how well our cells, tissues and organs are functioning compared to the global average. But what are the main drivers of this difference, and what can we do to keep our bodies younger and healthier for longer? In this episode, we’re joined by ageing and longevity expert and research director at Inserm in France, Jean-Marc Lemaitre to talk about his latest book, Choose Your Age – Unlocking the Cellular Science of Longevity. He talks us through the many factors that lead to some of us ageing more quickly than others, tells us what researchers can learn from how the world’s centenarians live their lives, and explains why we still don’t know what the limit for the human lifespan could be. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hello and welcome to Instant Genius, a Bitesize master class in podcast form. Every Monday and Friday you'll hear a world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. When it comes to the effects of aging on our bodies, there are many more factors of play than simply the number of years we've been alive. It turns out that for some people, there's a huge gap between their chronological age and their biological age,

the scientific measure of how well our cells, tissues and organs are functioning compared to the global average. But what are the main drivers of this difference? And what can we do to keep our bodies younger and healthier, but longer? In this episode, we're joined by aging and longevity expert and research director at InSAM in France, Jean-Marc Le Maître, to talk about his latest book, Choose Your Age, Unlocking the Cellular Science of Longevity. He talks us through the many factors that lead to some of us aging more quickly than others, tells us what researchers can learn from how the world's centenarians live their lives, and explains why we still don't know what the limit for the human lifespan could be.

So welcome to the podcast. Thanks so much for joining us. Thank you, Jasmine. So today we're talking about your new book, Choose Your Age, Unlocking the Cellular Science of Longevity. So one of the big things that you talk about in the book is the different ways that we can consider age. So you say chronological, biological, and physiological age. So first off, I think, you know, what do we mean by those? So in fact, chronological age is just the simplest age.

So the number of years since your births. And in fact, it's useful for administration, demography, for deciding when you can vote, drive, retire, or so on. But biologically, it's a very different crude measure. Two people can both be 16 years old chronologically, but one may have arteries, muscle, immune system, metabolism, and much younger than the other. So it means that what is really important is the aging of your body,

biology. And what would be now the best things to do for people to manage their age is to evaluate where they are in terms of biological age. So it means that with new technology, we can evaluate if you are younger or older in terms of your biology. And this is the most important because we know that aging is the major risk factor to have age-related disease. So this is the worst to be here with age-related disease because at the end, they accumulate and we become really non-healthy with the age if we accumulate this pathology. So it's really important to evaluate where we are. in terms of biological age.

And now we have the tools to do that, and the science can do that. Yeah, so let's have a look at that then. So what's going on when we do biologically age, you know, what's happening inside our bodies? And how do we go about measuring that? So in fact, now we know, and there is a consensus in the laboratory working on aging and longevity, we have different hallmark of aging that we can follow,

to see whether your cells and how your cells age. We know that with time, because our cells are really stressed every time, they experience during their life many different stress, and they damage, so they have to repair. And when they repair, they keep some hallmarks of this repair, and the physiology of the cells, become less and less efficient within. And we can now follow this with this kind of old mark. And it means that we can, with mathematics, with algorithm, calculate where you are

in terms of the biology of your cell, of your tissue, of your organ. Yeah. So you talk in the book about genetics. And, you know, this is a big thing. A lot of people say if you look younger or you're fitter when you're older. A lot of people will say, well, that person has good genes. How true is that? Genes are really important because we inherit of our genes and they are fixed for your life. But still we know that a big part of aging is epigenetic. So it's how you make your gene working. So whether your life is healthy or not, so it means whether you practice exercise, whether you have a good diet, healthy diet, and if you have a lot of connection, social relation, and even more, if you have in addition less stress, because stress is really

important for aging. And if you have all this, you can modify the mean of the action of your gene. So really, the impact of the epigenetic on aging is major. Yeah, so also in the book, you make a distinction between what you call normal aging and pathological aging. So I'd never heard that before, you know, what do we mean by that? So in fact, if you are evaluating, of biological age, so how your cell and your body age biologically, if it's in accordance with the algorithm and so on that we can calculate now, if it's in accordance with your chronological age, so it means that you age slowly and normally, it's normal, because aging is not inevitable. You can eventually save years in biology and so on, but still at the end, you finally age.

So if you are in accordance with your chronological age, everything is normal. But if your trajectory is bad, so it means that if you evaluate 15 years older for your body and your tissue and organ, probably you have to do something because either you will go into age-rated disease. This is really the major risk. Yeah, so let's have a look at longevity then. So is there a theoretical limit to the human lifespan? Do we know anything about that? In fact, we don't know, actually, if there is a limit.

The limit we have, and it's debated by demograph, by epidemiologists, and even biologists. And we know that the oldest woman was Jean Kalman, and it was 122 when she died. And maybe it's the limit, but we don't know. What we know is that more and more people reach 100 years. Why? It could be a combination of probably lifestyle,

because now we take care of many things in the life. But there is also probably the fact that the medicine, develop vaccination, antibiotics, and also now we have molecule, we have pill for age-related disease. So when we start to be diabetic, we have, for example, metformin. So you are not cured, but it becomes a chronic disease and you slow down the evolution of the pathology. So you can do that with cardiovascular disease, with Alzheimer's disease.

So at the end, you slow down the evolution of pathology, so you save years at the end. But probably if we would like to avoid this edge-related pathology, we have to look at what occur in the academic lab because we know now how to do to avoid age-related disease, because we have proof of concept with animal model. We know that if we treat aging, we delay dramatically or erase edged disease in animal models. So probably we have to go into this way to be healthy longer during your life and improve your healthy longevity. Yeah, so you mentioned that people living to 100 years or older. And there are some areas in the world that you talk about called blue zones that have a higher concentration of people.

a hundred years old and older, than anywhere, any other places in the world. So, you know, where are these places? And what are some of the things that we can learn from that? At the beginning, it was a meeting in Montpelier where I live and where I work. And it was a demographer and epidemiologists who present some specificity like that in their country, in Sardinia and in other five country. And they show that there is a higher concentration of of a centenarian people. Even in

Sardania, there is the same amount of centenarian men and women. So it was really amazing because we know that it's a 10% men and 90% of women. So, and

it was absolutely amazing. So they tried to understand why. And when they compare the lifestyle of these different people, the different country, even if they are different lifestyle, different diet, different area and environment, because in Okinawa is not the same in Sardania, they identify some pillars, a common denominator.

And its common denominator were exercise, so it means that people were always moving, have each day exercise. They also have really safe and alfi diet. So it means that there is a lot of vegetable, a low amount of meat, fishes and nuts and so on. They have also a huge number of interaction, social interaction, and a low level of stress. So it's probably the four pillars. And it's probably accessible to everybody. So this is probably the first step we have to promote, to really control our lifestyle, to stay healthy longer. Yeah, so let's have a look at some of the things that might be behind this then.

So I think one really interesting one is social interaction. You know, in this sort of after the pandemic when lots of people were isolating, there's been a lot of talk about the effects of loneliness and the importance of social interaction. But, you know, what does that do for it? Because you can see, like, interacting with people, maybe we'll keep your brain sharp and things like that. But what's actually going on? You know, what's the difference between somebody who is in a healthy social group,

someone who is perhaps a bit more isolated? Yes, but in this area, in this blue zone, there is a lot of social interaction. So it means that there is sometimes you can reading, but you can also interact with people. And when you interact with people, for sure, you make your brain working, but you have also satisfaction. So you are satisfied of the discussion and so on.

And probably if you are satisfied, it's good for your brain, but indirectly to your body also. Because if you feel good, you feel also healthy. So in fact, your brain interact with your body. We know that, for example, because there is the placebo effect, you know, so it means that you can act with your brain on your body and your health also. But for sure, if you have a lot of interaction, probably at the end, you have project also. And it's really important to have project because you make you moving when you have project for everything. You have to connect people. You have to develop new competence. You have to,

so probably it's really important to have a connection. What's about the study that really demonstrate this? We don't have, in fact, there is no real study that can say and demonstrate that the brain, an healthy brain, an healthy connection, social connection can impact. In fact, the body function. We know that if you are depressed with the age, we know that there is an impact, a negative impact. But the only things we know is that, for example, if you are positive person, so you try to slow down the stress, in fact, with the positive aspect. And we know that positive people live longer. And around 10 years. So it means that the stress, you know that the positive effect of your interaction and also the fact that you are able to positive your life

is important for longevity and healthy longevity. Sort of related to this, you also talk about how personal subjectivity comes into this conversation. I think this is a really interesting point, you know, the way people think about themselves in that age. So personally speaking, on the weekend, my dad turned 80. And I was talking to him about it and he says, it's crazy. I don't feel anywhere near this old. So presumably that's a good thing. You know, that feeds into this positivity idea.

Yes, probably, and I think feeling younger is often associated with better health. Less depression, better cognitive function and even probably lower mortality. Because, and probably if you think about it, if you think about it, this, can you exactly imagine which age you have really? Myself, I don't. I think probably I'm younger in my brain because sometimes I think I'm like a child. I don't know. No, you know, because I'm a researcher, you know, so I have to be a little bit of a child.

But anyway, in between 15 and 6. sometimes it's complicated for people to say exactly what age they are. Because we are in between. And this is probably the proof. It's really a subjective because at the end, people, when they are young, they want to be older because they want to be more. And when you are older, you would like to be. Probably at the end, you can decide of your age mentally.

with your brain. But for sure, you can also do that with your biology and to manage your biology to try to slow down aging. Yes. Going back to something you said earlier, you mentioned stress, the effect of stress. So, you know, everyone listening is going to have experienced stress at some point in their lives. And, you know, it's not a nice feeling. But this can have effects on our aging as well. Yes, exactly. And there is a, um, There is a lot of study on this, and especially on the telomere, you know, telomere, this is the, for the audience, this is the end of our chromatome, and each division of the cell, the telomere decrease in size. And when the telomere is too short, it trigger a mechanism, molecular mechanism, the name senescence.

and senescence is really a key driver of aging, because now it's really well-studied, and we know that it secret a lot of factors, inflammatory factors, and it disorganize the tissue, and make your tissue and your organ aging. So if telomere decreased too rapidly, you go more rapidly in senescence,

and you can see the consequence. So there is a lot of study on this, and we know that stress decrease telomere rapidly. For example, we know that a physician during their study, during their training, during their six years of training, we measure the size of the telomere. There is a study in US on this before and after the six years. and during the six years it decreased six times faster than the normal people. So it really, you know, because they were really stressed. And we also know that even stress when you are in the infancy,

it can have an impact during your late life. Another maybe late example is the nurse because they have a bad, organization of the life during the day, so they eat at different times, sometimes they work during the night, they have less sleep, efficient sleep, and so on. And at the end, they have shorter telomere than the global population also. So we really know that there is an impact of the stress, but not only on telomere, because we know also there is impact in oxidative stress. stress, metacondria dysfunction, and so on.

So globally, the stress make your cell aid. So let's have a look at some modern innovations then. Let's stick with the telomeres, you know. So say we've noticed that this effect is more pronounced in someone. Are there any new therapies that we can perhaps employ to slow down or perhaps even reverse this process? In fact, the reason why telomere decreased in size during our life is because the anxiety, the protein that allows that telomere stay at the same length during each division is named telomeres

and it's present during embryonic development but at the end when we are young and adult the telomerease is not anymore expressed so each time you decrease your each division you decrease your telomeree so Eventually, it could be a therapy with telomerase to restore the telomere size. But we know that also that in cancer cells, sometimes there is re-expression of telomeres to immortalize the cells. So it's probably not a good strategy or some people try to do that in clinical trial in US and so on. but it's not authorized by FDA for sure, and it could be dangerous.

But there is another way to try to decrease this impact of telomere decrease on senescence is the fact that we can also destroy senescent cells. So there is today some strategy with some molecules identified to trigger senesent cells and to kill them. So the senescent cells, you know, in the US, and we call that zombie cells. They are living, but they cannot divide anymore.

And they secret a lot of factors, but they cannot regenerate your tissue if there is damage. So it's a cell in between. And we know that it's a cell, key driver of aging because they secret these different factors. We know that with some molecules, senolytic molecules, you can destroy these cells. And there is actually a lot of clinical trial in US

to try to kill these senescent cells in many different pathology, from osteoarthritis, from lung disease, for diabetic people, and also even more for for Alzheimer disease and, you know, this kind of aging that geriatrician call frailty. You know, people when they age, they become sometimes fruity, and when they are fruity, they can basculate on an age-rated disease or dependency. So there is a clinical trial on this with one molecule to try to evaluate whether these frail people

can be reversed. And we don't have the result today, but there is a huge number of clinical trials. And maybe in the future, we could use this molecule to try to slow down the evolution of refrigerated disease. Also, probably, it's a little bit late because if you treat people with exaggerated disease,

probably the damage in the tissue is already done. So the best way would be to, to make prevention. So to see whether you are in your aging process by evaluating your biological age, it could be also implemented a sort of index of senations. And if you can evaluate that you are really older with a huge number of synest cells in your body,

probably you could use this xenolytic molecule. But today the problem is that ageing is not a disease. So it's complicated for medical doctor, for physician, to give appeal to somebody who is not healed. Yeah, so sort of one final question then. So for years and years and years in the past, life expectancy all around the world has slowly been increasing. But recently this increases as slowed down.

And in some cases, you know, it's, It's going backwards. So are you optimistic that we can, you know, continue to improve our longevity, not only our longevity, but also the lifespan, the amount of our lives that we remain healthy? Yes, in fact, actually we know that life expectancy

is a little bit stabilized. But when we speak about life expectancy, we speak about life expectancy at birth. So it means that the calculation of these parameters is done with the mortality of the year of the birth, of the person. But the mortality evolved during the time. And we know that there is actually more and more aging people. So with more aging people, you have an increase in mortality.

So probably the part of the fact that. that today it's stabilized. The best parameter to see, to look at the longevity is probably the age of the death. If you look at the age, the mean age of the death, the age of most people die, you can see that it continue to increase. In the 50, it's evaluate up to today. And we know that actually the age of the majority of people die is increasing. It does not stabilize. It is not stopped. So it means that it probably will continue. But the problem is, is it possible to continue this healthy or not? Because we know that we treat a lot of people with

with molecules, with drugs, for many different diseases, and they have a lot of chronic disease. They live longer, but not healthy. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Jean-Marc LeMaud. To discover more about the topics we've just discussed, check out his book.

Choose Your Age, Unlocking the Cellular Science of Longevity. If you liked what you heard, then please do consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then why not check out our YouTube channel at Science Focus? The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download us on your app store of choice. You can also find us on Apple News or online at sciencefocus.com. You know, Thank you.