Aug. 23, 2006 -- Baby boomers take note. Carrying around even a few extra pounds may shorten your life, a new government study finds.

The new research comes from the National Cancer Institute (NCI).

It contradicts a widely publicized study reported last year by researchers at the CDC. That study found the risk of death associated with being overweight or obese to be much lower than most public health experts believed.

While it is well known that middle-aged people who are obese have an increased risk of death, it has been less clear if that risk extended to people with just a few pounds to lose.

The new NCI study showed a 20% to 40% increase in the risk of death for healthy people with no history of smoking even if they were only overweight at age 50. If they were obese, they were two to three times as likely to die during the study's 10-year follow-up.

The issue is of critical importance to the aging population of the U.S., where one in three adults are obese and another third are considered overweight.

"This study contributes in an important way to understanding the risks of being overweight from the standpoint of early mortality," Michael F. Leitzmann, MD, an NCI researcher, tells WebMD.

Findings from the NCI study were mirrored in work done at Harvard University.
 

Harvard Findings

JoAnn Manson, MD, chief of preventive medicine at Harvard University's Brigham and Women's Hospital, and her Harvard colleagues took a look at last year's CDC findings soon after they were published. They excluded smokers and people who might have already been ill when enrolled in the trial.

And just like the NCI researchers, they found that being either overweight or obese was associated with an increased risk of early death in this healthier, nonsmoking subgroup.

The researchers who conducted the earlier CDC study suggested that public health efforts and aggressive treatments aimed at preventing chronic diseases had greatly reduced the obesity-related death risk.

"Because [the NCI] study was conducted over the past decade, these new findings go a long way toward dispelling that notion," Manson says.

"Overweight and obesity are still associated with excess mortality, and the management of chronic diseases associated with them will not eliminate this risk." she says.

"Prevention of obesity has to be a major public health priority," Manson tells WebMD. "These findings portend a very large burden of chronic disease and excess mortality in the decades to come as baby boomers age."

Half a Million in Study

The NCI study included half a million members of the AARP, the nation's largest group representing older Americans. Participants were between the ages of 50 and 71 at enrollment, and were followed for 10 years.

The researchers relied on self-reported estimates of current weight, and weight at age 50, taken from a questionnaire filled out by study participants when they entered the study.

There were 61,317 deaths during the 10-year follow-up, with the overall risk of death highest among the study subjects who had the highest and lowest body weights, as determined by body mass index (BMI), a ratio based on height and weight.

Someone with a BMI of less than 18.5 is considered to be underweight. A BMI of 18.5 to 24.9 is considered normal; 25 to 29.9 is considered overweight; and 30 or greater is considered obese.

For example, a 5-foot-7-inch person would be considered overweight, but not obese, at a weight between 160 and 190 pounds. Someone six feet tall who weighs between 185 and 220 pounds would also meet the BMI classification for overweight but not obese.