Some of the new research on possible causes of obesity is fascinating. New theories emerge continually, many of them at best inconsistent and at worst contradictory. But what interests me more is the debate that research sparks, which seems, at least in the popular arena, to be less about what actually causes obesity than about whose fault it is. It’s a subtle but important difference: the former is (largely, at least) a scientific question; the latter makes it a political or a philosophical one — and is, it seems to me, a thoroughly unhelpful approach.