Weight and mortality
In January, when the Journal of the American Medical Association (JAMA) published a meta-analysis of 100 studies that probed the relationship between body mass index and mortality — studies that found slightly overweight people have lower all-cause mortality than normal weight and underweight people — media around the globe trumpeted the news. Many suggested that scientists had failed to understand something crucial about health, and questioned whether carrying extra weight might be healthier than being slim. “When I read the article I was somewhat taken aback. I wondered if I should send a ‘never mind’ note to all the people I’d taught about the risks of excess fat,” said Jeffrey S. Flier, dean of the Faculty of Medicine, at Harvard Medical School (HMS) and an authority on the biology of obesity and diabetes. He wasn’t alone. Many others were perplexed by the findings gathered by Centers for Disease Control (CDC) epidemiologist Katharine Flegal,...