yay, fat (but not too much)

June 26, 2009 The New York Times
Excess Pounds, but Not Too Many, May Lead to Longer Life

By RONI CARYN RABIN

Being overweight won’t kill you — it may even help you live longer. That’s the latest from a study that analyzed data on 11,326 Canadian adults, ages 25 and older, who were followed over a 12-year period.

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.

“Overweight may not be the problem we thought it was,” said Dr. David H. Feeny, a senior investigator at Kaiser Permanente Center for Health Research in Portland, Ore., and one of the authors of the study. “Overweight was protective.”

He said the finding may be due to the fact that a little excess weight is protective for the elderly, who are at greatest risk for dying, or because many health conditions associated with being overweight, like high blood pressure, are being treated with medication.

The study took into account smoking status, physical activity, age, gender and alcohol consumption. It included a separate analysis excluding those who died early in the 12-year period, in order to weed out participants who might have been thin because they were smokers or had an underlying disease, like cancer.