Losing weight on purpose in old age may provide a survival edge, at least for obese people, a new analysis shows.
Writing in an upcoming issue of the Journal of Gerontology: Medical Sciences, researchers tackled a long-held assumption that weight loss in old age is uniformly unhealthy. The idea stems from overpowering data linking rapid, unintentional weight loss in the elderly to a hidden underlying problem, such as the onset of type 2 diabetes.
“The loss of weight over six months without a specific cause is a very bad prognostic sign,” says study coauthor Stephen Kritchevsky, an epidemiologist at Wake Forest University School of Medicine in Winston-Salem, N.C.
That has ingrained the notion among doctors that any weight loss in the elderly is risky, he says. “I’ve been at meetings on nutrition in the elderly, and there have been reputable geriatricians who have said in public that if you ask an older person to lose weight you’re committing malpractice,” he says.
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To assess the effects of intended weight loss, Kritchevsky and his colleagues analyzed data collected by a long-term trial in the 1990s. In the study 316 obese people, average age 70, were randomly assigned in roughly equal numbers to one of four interventions: a dieting program, dieting plus exercise, exercise only or health education only. The people had arthritic knees but were otherwise free of major health problems.
After 18 months, people in the weight-loss groups had shed 10 pounds, on average, whereas the nondieters had lost three. Over the following eight years half as many of the dieters died as did people in the nondieting group.
“This is a really valuable randomized study in elderly people,” says epidemiologist Kenneth Adams of Health Partners Research Foundation in Minneapolis, Minn. “The result is kind of unexpected.”
“I think the findings show potential benefits in obese people,” says Lewis Kuller, an epidemiologist at the University of Pittsburgh School of Public Health. “But I don’t think this is going to change doctors’ views about weight loss in the elderly.” That’s because people who lose fat also invariably lose some muscle and bone mass, he says.
The long-term effects of weight loss are difficult to track in health care studies because many people fail to keep the weight off. That means the number of people who stay thinner dwindles, and the study loses statistical power. When coupled with a mortality analysis — waiting to count the number of people who die during the trial follow-up — numbers shrink even further. For example, in this trial only 15 people in the weight-loss group died over the eight-year follow-up period compared with 30 in the nondieting group.
Even so, Adams says, “this is probably some of the best information we have on the effects of weight loss in the elderly.” Kritchevsky says the findings need to replicated before being applied to the clinical setting.