January 11, 2013

RETHINKING THIN: Last week, a study came out showing that overweight people had lower mortality than “normal” ones. There’s been a lot of pushback–but the arguments are pretty weak.

I do agree that mortality isn’t everything; morbidity (poor health) matters too. But it is not true that we are living longer, more miserable lives. On the contrary, active life expectancy is increasing faster than life expectancy, according to the experts I interviewed for an article in the Atlantic. You can see this in the proportion of people on Medicare who have limitations in their ability to perform the tasks of daily living, which has been falling, not rising. . . .

To be sure, it’s possible that these statistics would be even more awesome if folks were thinner–being heavy is indisputably hell on the joints. But it is simply not the case that we are collectively living longer, unhealthier lives than we used to. And being thin can also be associated with morbidity problems–you’re more likely to hurt yourself when you fall, for example, because there’s no padding.

As for the last point, it seems a bit rich for public health experts and health journalists to suddenly be arguing that, well, of course, BMI doesn’t really tell you how fat people are. For twenty years, we’ve been reading about America’s obesity epidemic, which was going to kill us all in our beds, bankrupt the health care system, and Jesus Christ, have you seen how these people look in sweatpants? All of those articles were based on . . . rising BMI’s. That’s because we have no idea how much body fat has increased. It’s absolutely true that visceral fat predicts mortality better than many other measures, but visceral fat is really difficult and expensive to measure, so we mostly haven’t.

Read the whole thing.