Researchers found that while underweight and extremely obese people die earlier than people of a normal weight, people who are slightly overweight actually live longer than those of a normal weight.
The findings of the new study were published online in the journal Obesity by researchers at Statistics Canada, Kaiser Permanente Center for Health Research, Portland State University, Oregon Health & Science University, and McGill University.
"It's not surprising that extreme underweight and extreme obesity increase the risk of dying, but it is surprising that carrying a little extra weight may give people a longevity advantage," researcher David Feeny from the Kaiser Permanente Center for Health Research said in a statement.
But fellow researcher Mark Kaplan, professor of Community Health at Portland State University, said while a few extra pounds may protect older people as their health declines, that did not mean people of normal weight should try to add bulk.
"Our study only looked at mortality, not at quality of life, and there are many negative health consequences associated with obesity, including high blood pressure, high cholesterol, and diabetes," said Kaplan.
The study was based on examining the relationship between body mass index and death among 11,326 adults in Canada over a 12-year period using data from the National Population Health Survey.
During the study period, from 1994/1995 through 2006/2007, underweight people were 70 percent more likely than people of normal weight to die, and extremely obese people were 36 percent more likely to die.
But overweight individuals were 17 percent less likely to die. The relative risk for obese people was nearly the same as for people of normal weight.
The researchers said this was the first large Canadian study to show that people who are overweight may actually live longer than those of normal weight. An earlier study, conducted in the United States and published in 2005 in the Journal of the American Medical Association, showed similar results.