Since 2005, when Katherine Flegal of the National Center for Health Statistics began reporting that people whom the government deems “overweight” appear to be healthier than people who stay within the recommended weight range, her work has provoked outrage from other obesity researchers. As Virginia Hughes explains in a recent Nature feature story, the critics’ main complaint is not that Flegal’s findings are wrong but that they are unhelpful. Hughes describes the reaction to a meta-analysis of 97 studies that Flegal and her colleagues published last January in The Journal of the American Medical Association, which found that mortality rates were lowest among people considered overweight but not obese…