The last 200 years has seen quite a profound change in our lives. We’re living longer, and longer, and longer. As you can see over the last couple of hundred years, we’ve gone from living in our 40s and 50s, now to having a one-in-three chance of a baby today living to the age of 100. And the drivers behind that were originally around changes in hygiene and nutrition, but are more recently around medicine, so we’re better able to manage cardiovascular disease. So the challenge for us is, how do we have good quality later years? And that’s where lifestyle plays a real key.
We know that because if we have a look at the effect of longevity, all of us are not living longer. Some of us are. Some of us are not. And that ties down to where you live, your type of food, the environment that’s around you. It’s not down to your genome. Your genetics haven’t changed in the last 100 years. Whereas your environments really have. And that’s been really important because we’re getting bigger. Our lifestyles are fundamentally changing. We’re larger than we used to be, even 20 years ago. We’ve gone from having a prevalence of obesity of less than 10%, now to 30% or 40% and, in some areas, 50% obesity.
The environment is changing, but in quite subtle ways that we don’t really tend to think about. It’s not food, but it is the number of dishwashers sold. It is the number of washing machines. It is the number of cars. And if we count up the number of calories from those activities through our everyday life, so that’s walking up and down stairs, washing the dishes, that’s about 110 calories. Now, 110 calories is half a Mars bar. So if I was to eat half a Mars bar a day without changing anything else and came back in 12 months time, do you think I’d be bigger? Well, likely, yes. But the important thing there is I haven’t changed the food.
It’s just the things around me that are changing, things I haven’t really thought about. And we’ve known about the importance of your everyday activity for a long time now. So over 60 years ago, one of the first pieces of science was done by Jerry Morris. And Jerry Morris looked at London bus drivers and bus conductors, and he showed that the bus drivers were more than twice as likely to have a heart attack than the bus conductors. Now this, importantly, is not exercise. This is just how much you move in your everyday life. And the more recent work is showing that this doesn’t just relate to heart disease, but it relates to all causes of death for older people.
And the relationships with just sitting time, in particular, are even stronger. And in women who have a very high sit time versus women who have a low sit time, they’re more than three times as likely to have heart disease. Your activity patterns play an important role because doing nothing means that your body deconditions. If you don’t use your body, it loses fitness very, very quickly. Now, importantly, fitness is not your ability to run around an 800-metre track. Your fitness is the ability for your body to take in oxygen, your heart to pump it around the body, and then it get used muscles. So it is a very powerful marker, or we call them biomarkers, of well-being.
Although the environment is powerful in managing your fitness levels, the problem that we have is that your body’s pre-programmed to start to wind down from about your mid-30s. This hits the point where your fitness level means you can’t get out and about, and do the things that make you you. So you’re physically not fit enough to go to the shops, to go to bingo, to go and see your friends. You’ve become socially isolated. You stay at home. You do less and less. And you end up with this spiral of decline. You can moderate this by managing your weight and managing your physical activity levels.
In fact, the difference between being normal weight and physically active, and overweight and physically inactive is a striking 20 years of independent living. The key to this is behaviour. And we’re only just starting to learn how and why we do the things that we do. So if we look at obesity as an example, obesity rates are clustered. So if your friends are overweight, you’re more likely to be overweight. If your friends are normal weight, you’re more likely to be normal weight. And the reason for that is you get a cluster of behaviour. Because when I go to see my friends, we eat the same things. We do the same things.
So the challenge for us, if we really want to have good, healthy ageing, is to begin to challenge how groups work. So in terms of the tools that we have to promote healthy ageing, activity and diet are the two most potent tools that we have. And the science is so strong. The challenge is, how do we get people to do it?