From the New York Times, an article that made my day: Excess Pounds, But Not Too Many, May Lead to Longer Life.
The report, published online last week in the journal Obesity, found that overall, people who were overweight but not obese — defined as a body mass index of 25 to 29.9 — were actually less likely to die than people of normal weight, defined as a B.M.I. of 18.5 to 24.9.
By contrast, people who were underweight, with a B.M.I. under 18.5, were more likely to die than those of average weight. Their risk of dying was 73 percent higher than that of normal weight people, while the risk of dying for those who were overweight was 17 percent lower than for people of normal weight.The finding adds to a simmering scientific controversy over the optimal weight for adults. In 2007, scientists at the Centers for Disease Control and Prevention and the National Cancer Institute reported that overweight adults were less likely than normal weight adults to die from a variety of diseases, including infections and lung disease.