A series of epidemiological studies, none big enough to be probative, but all pointing in the same direction, persuaded Emma Wilmot of the University of Leicester, in Britain, to carry out a meta-analysis. This is a technique that combines diverse studies in a statistically meaningful way. Dr Wilmot combined 18 of them, covering almost 800,000 people, in 2012 and concluded that those individuals who are least active in their normal daily lives are twice as likely to develop diabetes as those who are most active. She also found that the immobile are twice as likely to die from a heart attack and two-and-a-half times as likely to suffer cardiovascular disease as the most ambulatory. Crucially, all this seemed independent of the amount of vigorous, gym-style exercise that volunteers did.
Correlation is not, of course, causation. But there is other evidence suggesting inactivity really is to blame for these problems. One exhibit is the finding that sitting down and attending to a task—anything from watching television to playing video games to reading—serves to increase the amount of calories people eat without increasing the quantity that they burn. Why that should be is unclear—as is whether low-level exercise like standing would deal with the snacking.To be sure, the science is not complete on this issue, but this is a prescription that is pretty easy to swallow, and it probably behooves us all to keep in mind the old US football cheer: "stand up, sit down, fight, fight, fight." It might be the fight of our lives.