Carrying a little extra weight may actually extend your life, a new study using Canadian data has found.

The study authors stress, though, that their findings do not mean that those of normal weight should aim to put on a few pounds.

The study was conducted by researchers at Statistics Canada and in the U.S. and used data from the 1994-95 National Population Health Survey. It looked at the relationship between body mass index and death among 11,326 adults in Canada over a 12-year period.

The data revealed that underweight people and those who are extremely obese die earlier than people of normal weight -- a finding that surprised no one.

But researchers were surprised to see that carrying a little extra weight may give people a longevity advantage. They found that those with a BMI between 25 and 30 had a significantly decreased risk of death in the 12-year follow-up period of the study.

Underweight people were 70 per cent more likely than people of normal weight to die, and extremely obese people were 36 per cent more likely to die. But overweight individuals were 17 per cent less likely to die.

The study authors note that many of the deaths occurred among the elderly -- a population for whom a little extra weight may be healthy.

Dr. Yoni Freedhoff, medical director of the Bariatric Medical Institute, says that's an important point.

"It's been shown before that having a few extra pounds in our geriatric years may actually confer some protection against early death," he told CTV News Channel from his weight management centre in Ottawa.

"No one is certain why a little extra weight is good in our older years, but the working theory is that weight provides people with an energy reserve so that when people are hit with illnesses as we get older -- which we are unfortunately prone to do as we grow older - we have this reserve of energy to draw on and to allow us to weather that illness."

The authors also note that even if extra weight extends life, that does not mean that it improves health.

"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," noted study author Mark Kaplan, Professor of Community Health at Portland State University.

Dr. Keith Bachman, a weight management specialist with Kaiser Permanente's Care Management Institute agreed, noting that good health is more than a number on the scale.

"We know that people who choose a healthy lifestyle enjoy better health: good food choices, being physically active every day, managing stress, and keeping blood pressure, cholesterol, and blood sugar levels in check."

An earlier study, conducted in the United States and published in 2005 also found that people who are overweight may live longer than those of normal weight. This study, published in the journal Obesity, is the first large study to make the same finding among Canadians.