A couple of years ago, a team of researchers led by Katherine Flegal of the U.S. Centers for Disease Control and Prevention looked at data from the the National Health and Nutrition Examination Survey and discovered that the mortality rate for people the government considers "overweight" was lower than the mortality rate for people with weights the government deems "normal," "healthy," or "optimal." The study did find a higher death rate among people fat enough to be considered "obese" (and among the "underweight"), but it implied a much lower annual death toll associated with excess weight than the CDC had been claiming: about 100,000, as opposed to 400,000 or so. (If you take into account the lower mortality rate among the merely "overweight," the net number of "excess deaths" among those who weigh more than the governnment thinks they should is about 26,000.) Just as important, the study cast doubt on the meaning of the "overweight" label, since it showed that the government-preferred range is not only not "normal" (since most people exceed it); it may not even be "optimal" in terms of health. Now (as Ron Bailey notes below) Flegal and several other government-employed scientists are back with a detailed look at causes of death in various weight ranges.
The new study—published, like the earlier one, in The Journal of the American Medical Association—finds that the excess deaths among the obese are overwhelmingly due to cardiovascular disease. The category "diabetes and kidney disease" comes in second. While the overall cancer death rate was not higher than in the "normal" weight group, certain cancers (colon, breast, esophagus, uterus, ovary, kidney, and pancreas) were slightly more common. By contrast, compared to people of "normal" weight, those who were merely "overweight" (but not "obese") had lower rates of death from a variety of causes, including respiratory disease, Alzheimer's, and Parkinson's. Flegal et al. say the differences remained after they controlled for smoking and pre-existing disease, both of which are associated with lower weight.
Standing alone, these data do not prove that plumpness is healthy or that thinness kills. But they do cast doubt on the conventional wisdom that everyone should strive for a government-approved weight. In response to Flegal et al.'s research, JoAnn Manson, chief of preventive medicine at Boston's Brigham and Women's Hospital, tells The New York Times "health extends far beyond mortality rates," which is true enough. In particular, Manson notes that "excess weight makes it more difficult to move about and impairs the quality of life." But that sort of day-to-day impairment is much more obvious than the lurking, lethal risk of a few extra pounds that Manson has been warning people about for years. A 1995 New York Times headline inspired by one of Manson's studies warned that "Even Moderate Weight Gains Can Be Deadly." The story quoted Manson's prediction that "it won't be long before obesity surpasses cigarette smoking as a cause of death in this country." It looks like both of those claims were wrong, which is good news not only for "overweight" people but for anyone worried about the social engineers with plans for making us thinner.