WEIGHT LOSS Weight Loss Mortality Examined
According to a new study appearing in the March 4, 2002 issue of Annals of Internal Medicine, the lowest death rates were in people who tried and actually succeeded in losing modest amounts of weight, while the highest rates were in people who lost weight without really trying.
Although countless studies have looked at weight loss and mortality rates, none has looked at unintentional weight loss vs. intentional weight loss, and few have looked at long-term results.
"There's an ongoing paradox in weight-loss research as it relates to long-term outcomes," says Edward Gregg, lead author of the study and an epidemiologist with the National Center for Chronic Disease Prevention and Health Promotion in Atlanta. "There's a whole lot of evidence that, in the short term, people who are overweight, when they lose weight, they have improvements in a whole lot of risk factors. And at the same time, there's also a fair amount of evidence that people who are at high risk for hypertension and diabetes will reduce their risk of developing those disorders if they lose weight."
Other research, however, has linked weight loss to an increased death rate over the long haul, the study says.
Here, the researchers analyzed data from 6,391 overweight and obese American adults 35 years or older who were part of the National Health Interview Survey. The participants had responded to questions about whether or not they had tried to lose weight.
After analyzing the data, the researchers discovered that people who tried and succeeded in losing weight had a 24 percent lower mortality rate than people who didn't try to lose weight and whose weight remained stable.
"People trying to lose weight had a lower death rate essentially regardless of whether they lost. However, the lowest rates was associated with modest intentional weight loss," Gregg says.
"Trying to lose weight may be an important factor above and beyond how much you succeed, so I think the best advice we can give at present is for overweight people to try to achieve gradual weight reductions with lifestyle changes," Gregg adds.
People who lost weight without trying had a 31 percent (the range was 29 to 77 percent) higher death rate. "To me, unintentional weight loss almost always means people have some dread disease," says Dr. John Maylard, a cardiologist with the Ochsner Clinic Foundation in Covington, La. "This is not a society where people just lose weight for no reason."
One unexpected finding was a lower mortality rate among people who gained weight while reporting that they were not trying to lose. This link was found mostly in men and disappeared after excluding people who smoked.
One limitation to the research is that the data was reported by the participants themselves, rather than by an impartial expert. It's also not a randomized, controlled trial like one now under way through the National Institutes of Health.
Limitations notwithstanding, why would trying and failing to lose weight be associated with living longer?
Possibly because these people are watching what they eat and are also are engaging in other positive health behaviors, such as wearing seat belts, drinking alcohol in moderation, and seeing their doctor on a regular basis.
Their weight may also be more stable. "These people probably are moderating what they get into. They may not be losing too much, but they're not gaining too much either," Maylard says.
And exercise may be a factor as well. "These people may also be engaged in higher levels of physical activity, which has been associated with lower mortality even though more physical activity doesn't mean you will be more successful at losing weight," Gregg says. "The same may be true with certain dietary approaches. People who reported trying to lose weight may be eating healthier diets. I don't think it's really clear yet that it's actually the weight per se that someone loses or is it the behaviors underlying it."
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