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The Ups and Downs of 'Yo-Yo' Dieting
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FRIDAY, Oct. 24 (HealthDay News) -- For some frequent dieters, weight loss is a vicious cycle. They're gung-ho in the beginning, and the pounds melt away, but not for long. Once they stray from their diet, all the weight that was lost makes a comeback.
In fact, a 2006 review in the International Journal of Obesity by Swiss researchers of the scientific evidence noted an association between weight fluctuations and cardiovascular disease and death.
"I agree that data on weight cycling are mixed, particularly on weight regain, decreased energy expenditure, etcetera," said lead author Dr. Jean-Pierre Montani, professor and chair of physiology at the University of Fribourg.
"However, there is increasing evidence that weight cycling may lead to cardiovascular and metabolic disorders," such as hypertension and diabetes, he added. "And the risk of complications of weight cycling seems greater in people with normal weight or slightly overweight than in obese people."
But other experts say the news on weight cycling may not be as bad as it seems, and it shouldn't discourage people from trying to lose weight.
"From my perspective, it's so worth it to try (losing weight), even if it's the sixth time," said Dr. Michael L. Dansinger, an assistant professor of medicine and obesity researcher at Tufts-New England Medical Center in Boston. "It's the people who never give up trying who are eventually going to succeed."
Weight cycling can refer to a small weight loss and regain of 5 to 10 pounds, or a large cycle of 50 pounds or more, according to the Weight-control Information Network, a service of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
And at least some of the studies suggesting that repeatedly losing and gaining weight poses health risks fail to separate intentional weight loss from unintentional weight loss, one expert maintained.
"People who lose weight unintentionally may be losing weight due to a disease, such as cancer, or depression," explained Alison E. Field, associate professor of pediatrics in the Division of Adolescent Medicine at Children's Hospital Boston. "Those weight losses one would expect to look bad for your health, because they are the result, not the cause, of disease."
Field, who studies intentional weight loss, added, "In our ongoing work, weight cyclers do not appear to be more likely to die."
The U.S. National Task Force on the Prevention and Treatment of Obesity found that, while conclusive data regarding the long-term health effects of weight cycling are lacking, the potential risks do not outweigh the potential benefits of weight loss in significantly obese patients.
Dansinger's own research on dieting suggests that overweight people should never give up trying to lose weight.
He and colleagues examined the effect of dieting advice on people's weight loss over time. The team performed a "meta-analysis" -- a study of studies -- comparing people who were counseled to change their dietary patterns, with members of a control group who received little more than general verbal or written advice on dieting.
Their study, published recently in the Annals of Internal Medicine, found that people who got dietary counseling lost an average of 6% of their body weight within a year, compared with the control group.
What Dansinger didn't fully appreciate at the time were the implications for weight cycling. While both groups regained virtually all of the weight they had lost after five years, the active weight-loss group, on average, did as well as, or better than, the control group.
"And so, this study actually helps provide strong evidence to address that question about whether someone's worse off due to trying (to lose weight), and the answer is no. There's no sign that losing the weight results in a worse final weight than in the control group," Dansinger explained.
"I agree that it never hurts to try," said Field, adding that people should move away from diets and strive for lifestyle changes.
"A lifestyle change would be to make smaller changes to diet that someone could stick with, such as decreasing the number of cans or bottles of soda, sports drinks and other sweetened beverages and watching one hour per day less of television," she said. "Additional changes could be done gradually, but the goal would be long-term weight control rather than large rapid weight losses."
SOURCES: Jean-Pierre Montani, M.D., professor, chair of physiology, University of Fribourg, Fribourg, Switzerland; Alison E. Field, Sc.D., associate professor, pediatrics, Division of Adolescent Medicine, Children's Hospital Boston; Michael L. Dansinger, M.D., assistant professor, medicine, and obesity researcher, Tufts-New England Medical Center, Boston; U.S. National Institute of Diabetes and Digestive and Kidney Diseases, December 2006, supplement, International Journal of Obesity; July 3, 2007, Annals of Internal Medicine
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