From the perspective of health and longevity, the three most damaging things that people commonly do to themselves are (a) take up smoking, (b) lead a sedentary lifestyle, and (c) become obese. A sizable percentage of the population in the wealthier regions of the world falls into at least one of those buckets. The result for near all such people is higher lifetime medical expenses, greater ill health, and a shorter life. The damage done scales by the degree to which an individual smokes, fails to exercise, or puts on weight: there is plenty of evidence to show that even a little additional weight is harmful in the long term, for example. I think that by now the consequences of smoking are widely appreciated, but awareness that choosing to lead a sedentary lifestyle or to carry a lot of excess fat tissue is just as bad? That has yet to spread to the same degree. The open access paper I'll point out today is one of those that finds the losses of life or health caused by obesity and inactivity to be greater than the losses caused by smoking.

How do these choices produce damage that looks a lot like accelerated aging, increasing the incidence of age-related disease, and causing higher mortality rates? I shouldn't have to dwell on the results of smoking for this audience: greatly increased inflammation; particulate matter in the lungs; increased risk of cancers, fibrosis, and cardiovascular disease; and so on. How is it that inactivity and obesity can achieve the same level of harm? In the case of obesity, visceral fat tissue is the driver of damage. It is a very active tissue, producing significant changes in the operation of metabolism and the organs it wraps: metabolic syndrome, type 2 diabetes, and so forth. Visceral fat tissue also produces higher levels of chronic inflammation throughout the body through its interaction with immune cells, and inflammation speeds the development of cardiovascular disease, dementia, and most of the other ultimately fatal age-related diseases. In the case of a sedentary lifestyle, it is easier to look through the literature to find the gains produced by exercise rather than searching for the losses produced by a lack of exercise. Exercise slows the stiffening of blood vessels that leads to cardiovascular disease, increases cellular maintenance activities, improves the immune system by culling unwanted cells, and much more. Like calorie restriction, exercise changes almost every measure of metabolism for the better.

Thus we have this paper, which like so many others catalogs the damage that people inflict upon themselves through poor choices. One day, probably later in this century, none of this will much matter, because medical science will be able to rescue everyone from the consequences of such poor choices - and then add decades of additional healthy life on top of that, by addressing the root causes of aging. We are not there yet, however, and in a world in which progress is rapid, every additional few years of expected life span might make the difference between dying too soon and living to benefit from the first effective rejuvenation therapies. Far and away the most reliable way to add those years today is to take better care of your long-term health.

Smoking, physical inactivity and obesity as predictors of healthy and disease-free life expectancy between ages 50 and 75: a multicohort study