Just in time for those New Year's resolutions about diet comes this surprising news: While being obese is still bad for your health, new research suggests that those who are moderately overweight have a lower risk of dying than normal-weight people do.
The study, published this week in the Journal of the American Medical Association, is a big one - an analysis of 100 international studies that included about 3 million adults. The authors were researchers with the National Center for Health Statistics, part of the Centers for Disease Control and Prevention (CDC).
Their findings suggest that while overall obesity and higher levels of obesity were both associated with a significantly higher risk of death, those considered overweight or at the lowest obesity level (a body mass index of 25 to 35) had a significantly lower risk of death.
Translation: Maybe being plump isn't so bad for you.
But other experts disagreed with this implication, some of them vehemently. Walter Willett, M.D., of the Harvard School of Public Health, wasn't having any of it. He told NPR he had read the study and thought it was "a pile of rubbish and no one should waste their time reading it."
The study looked at only the association between body mass index - a calculation of height and weight - and death, without taking into account the specific reason for a person's death, Willett said. Maybe more thin people died because illness had already caused them to lose a lot of weight. Maybe overweight people live a bit longer but suffer from more chronic disease. The study didn't answer any of this, he said.
Other physicians worried that people would think this gives them a free pass to pack on the pounds. They argued that extra weight is OK only if the rest of your health is OK. If you're already suffering from high blood pressure or high cholesterol, then losing weight might still be a good idea.
"Body mass index is an imperfect measure of the risk of mortality," and factors like blood pressure, cholesterol and blood sugar must be considered, Samuel Klein, M.D., director of the Center for Human Nutrition at Washington University School of Medicine in St. Louis, told the New York Times.
Paul Campos, author of a book on obesity, wrote in an op-ed column in the Times that the findings mean that a 5-foot-4-inch woman weighing between 108 and 145 pounds would have a higher risk of death than a woman of the same height weighing between 146 and 203 pounds. He jokingly wondered if public health officials would now tell so-called normal-weight people "to put on some pounds, so they can move into the lower risk, higher-weight categories."
Although this study is not the first to suggest that a few extra pounds may not always be a health threat, the Times called it "by far the largest and most carefully done." Lead author Katherine Flegal of the CDC and her colleagues found a 6 percent lower risk of death for those who are moderately overweight, while the most obese had a nearly 30 percent higher risk of death.
An editorial accompanying the study also mentioned this "obesity paradox," in which a moderate amount of excess weight seems to have a beneficial effect in fighting off disease or recovering from traumatic injury, particularly as people age, according to Steven Heymsfield, M.D., and William Cefalu, M.D., of the Pennington Biomedical Research Center in Baton Rouge, La.
Heymsfield, however, also agreed that other health factors need to be considered. As he told the Times: For overweight people, if indicators like cholesterol "are in the abnormal range, then that weight is affecting you," but if indicators are normal, there's no reason to "go on a crash diet."