For four decades, obesity rates have climbed across the world despite campaigns, warnings, and countless individual attempts at change — and a new study in The Lancet suggests the reason is not a failure of human will but a collision between two self-reinforcing forces: a food system built to profit from processed abundance, and a biology built to hold onto every calorie it gains. The question was never whether people were trying hard enough; it was always whether the environment in which they were trying was designed to let them succeed.