Learning to love the middle aged spread

A feature report at Nature on the vexed issue of how much weight gain is actually bad for you:

But many researchers accept Flegal's results and see them as just the latest report illustrating what is known as the obesity paradox. Being overweight increases a person's risk of diabetes, heart disease, cancer and many other chronic illnesses. But these studies suggest that for some people — particularly those who are middle-aged or older, or already sick — a bit of extra weight is not particularly harmful, and may even be helpful. (Being so overweight as to be classed obese, however, is almost always associated with poor health outcomes.)

The paradox has prompted much discussion in the public-health community — including a string of letters in JAMA last month² — in part because the epidemiology involved is complex, and eliminating confounding factors is difficult. But the most contentious part of the debate is not about the science per se, but how to talk about it. Public-health experts, including Willett, have spent decades emphasizing the risks of carrying excess weight. Studies such as Flegal's are dangerous, Willett says, because they could confuse the public and doctors, and undermine public policies to curb rising obesity rates. “There is going to be some percentage of physicians who will not counsel an overweight patient because of this,” he says. Worse, he says, these findings can be hijacked by powerful special-interest groups, such as the soft-drink and food lobbies, to influence policy-makers.