Underweight and extremely obese people die earlier than those having normal weight, results of an international study conducted by Canadian and American researchers have revealed.
The same study, however, also shows that overweight people actually live longer than those having normal weight.
"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," said Dr. David Feeny, co-author of the study and senior investigator for the Kaiser Permanente Center for Health Research.
"It may be that a few extra pounds actually protect older people as their health declines, but that doesn't mean that people in the normal weight range should try to put on a few pounds.
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 Mark Kaplan, co-author and Professor of Community Health at Portland State University.
Dr. Keith Bachman, a weight management specialist with Kaiser Permanente's Care Management Institute, added: "Good health is more than a BMI or a number on a scale. We know that people who choose a healthy lifestyle enjoy better health: good food choices, being physically active everyday, managing stress, and keeping blood pressure, cholesterol, and blood sugar levels in check."
The study examined the relationship between body mass index and death among 11,326 adults in Canada over a 12-year period.
The researchers observed that underweight people had the highest risk of dying, and the extremely obese had the second highest risk.
According to them, overweight people had a lower risk of dying than those of normal weight.
The researcher claim that theirs is the first large Canadian study to show that people who are overweight may actually live longer than those of normal weight.
For the study, the researchers used data from the National Population Health Survey conducted by Statistics Canada every two years.
They say that 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.
However, overweight people were 17 percent less likely to die. The relative risk for obese people was nearly the same as for people of normal weight.
The findings have been reported in the online edition of the journal Obesity.