Scientists continue to gather more evidence that sitting around all day is bad for you.
Specifically, sitting for more than three hours a day cuts your life expectancy by two years, a new study published this week in BMJ Open says. Watching TV makes things even worse: If you watch for two hours a day, your life expectancy drops by another 1.4 years.
This study supports earlier studies, all of which should make you nervous about sitting down.
For example, according to another study, every hour of TV you watch cuts 22 minutes off your life (slightly less for women). Men who don't watch TV live 1.8 years longer than men who do.
Why is sitting bad for you?
According to James Vlahos in the New York Times, here's what happens when you sit:
Electrical activity in the muscles drops — "the muscles go as silent as those of a dead horse," inactivity researcher Marc Hamilton says — leading to a cascade of harmful metabolic effects.
Your calorie-burning rate immediately plunges to about one per minute, a third of what it would be if you got up and walked.
Insulin effectiveness drops within a single day, and the risk of developing Type 2 diabetes rises. So does the risk of being obese.
The enzymes responsible for breaking down lipids and triglycerides — for "vacuuming up fat out of the bloodstream," as Hamilton puts it — plunge, which in turn causes the levels of good (HDL) cholesterol to fall.
In short, sitting makes you fat, weak and more likely to get sick.
Another bummer: You can't counteract the harmful effects of sitting by exercising once in a while. If you exercise a lot but also sit around a lot, you'll still have a shorter lifespan than people who don't sit so much.
But here's some good news:
You don't have to start running marathons to offset all that sitting. You also don't have to get a treadmill at the office and sweat all day. You just have to get up every hour or two and walk around for a while. Or, alternatively, you just have to stand instead of sit.
A year ago, after reading some of these studies, I decided to spend half the day standing at work instead of sitting. In doing so, I was following in the footsteps of my Yahoo! colleague Aaron Task, who also stands.
Well, in the beginning, it was torture: I was exhausted by the time lunch came around. I also began to look forward to meetings (which I normally avoid), because they provided a chance to sit down. And I felt like a freak standing at a desk in a newsroom surrounded by 75 happy, sitting people.
But did it help anything?
Well, I don't know whether I'm any healthier, but I've lost some weight. And it isn't that hard to stand any more, which suggests that I've gotten stronger. And this new habit doesn't seem to have hurt me.
So I'm going to keep at it.
At least until a study appears that concludes that, by standing, I'm actually killing myself.
SEE ALSO: Sitting Can Kill You