Effect of Life Choices on Life Expectancy

We made our life expectancy calculator because many people, when trying to be healthy, worry about the wrong things. Determining what effects health is tricky. Fortunately, there are excellent records on who dies when, and why they died, giving us a better idea of what effects life expectancy and hence, more generally, health.

What determines how long you will live?

It helps to "choose" parents with good genes and, equally importantly, to be well educated (choosing your parents well helps there, too). But more importantly, what can you control that effects your longevity? Some choices are obvious: don't smoke, don't drive a car too much--or at least wear a seat belt and be sober when you do drive, and wear a helmet when you bicycle.

You're good on most of those. So what can you do? Exercise. As best we can tell, you get an extra two hours of life for each hour you exercise. That may not sound like much, but an hour a day of exercise would give you an extra month of life per year, or an extra year of life per decade. And that life, particularly toward the end, will be (on average) of better quality.

You should also have good friends and be happy. People with stronger friendships are happier, and they live longer. Exact numbers are hard to come by, but recent studies suggest that people with good relationships live roughly five years longer than social isolates. You gain as much life expectancy from happiness as you would lose if you smoked. Socializing also helps maintain brain function Forget doing crossword puzzles to sharpen the mind; talking to friends is much more stimulating.

Beyond exercise and friendships, almost nothing you do matters for life expectancy. Being morbidly obese is bad, and evidence suggests that severe calorie restriction (if you can stand being hungry all the time) leads to longer life, but most dieting doesn't work, and being slightly thinner won't make you live slightly longer. Eating healthily is no doubt good, but no one has convincingly showed that doing so increases life expectancy.

Exercise and be happy!

- Professor Lyle Ungar
University of Pennsylvania