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Study shows long-term weight control is achievable

March 12, 2008

People who shed weight and want to keep it off might benefit from monthly personal contact interventions, researchers reported at the American Heart Association's Conference on Nutrition, Physical Activity and Metabolism.

Results of the study will also be simultaneously published in the Journal of the American Medical Association.

In a test of three ways that might help people maintain weight loss, those who received monthly personal counseling were best at keeping off unwanted pounds. Overall, 42 percent of the study members maintained at least a 4-kilogram (9-pound) weight loss for 30 months.

"We know how to help people lose weight in a healthy way, but we know very little about how to help them to keep the weight off," said Laura P. Svetkey, M.D, lead author of the study and professor of medicine at Duke University Medical Center in Durham, N.C. "This study is the longest and largest to test strategies for long-term weight loss maintenance, and it suggests that long-term weight control is an achievable goal.

"The United States is in the midst of an obesity epidemic, one that portends serious future health consequences. Overweight and obesity are the leading cause of high blood pressure, diabetes and abnormal cholesterol, which are leading causes of cardiovascular disease, which is, in turn, the leading cause of death in this country," Svetkey said. "So if we really want to get to the root causes of these disorders, we need to address the obesity epidemic."

Despite the importance of obesity control, few studies have tested strategies to maintain weight loss over long periods. Svetkey and her colleagues enrolled 1,685 participants in the two-phase Weight Loss Maintenance trial, which was conducted at four clinical centers in the United States.

Phase I consisted of 20 weekly group sessions of 18-25 participants held over six months, during which trained counselors emphasized three key elements to weight loss - consuming fewer calories, increasing moderate physical activity, and eating a healthy diet.

Researchers recommended DASH (Dietary Approaches to Stop Hypertension), a diet rich in fruits, vegetables, whole-grain and high fiber foods, that uses low-fat and fat-free dairy products and is low in total and saturated fat and sodium. DASH lowers blood pressure and cholesterol even without weight loss.

Counselors helped participants use tools like self-monitoring and goal-setting, and helped them remember why they wanted to lose weight in the first place. The group sessions also provided study members with social support from other participants.

At the end of Phase I, 61 percent of the participants in the trial were eligible for Phase II, which lasted for 30 months, because they had lost at least nine pounds and as much as 66 pounds.

Thirty-eight percent of people in Phase II were African-American and 37 percent were male. "This is important because men are often underrepresented in weight loss studies, and obesity disproportionately affects African Americans," Svetkey said.

Researchers randomly assigned the volunteers to one of three groups:

* Personal contact (PC) - Participants talked with an interventionist (monthly, nine times by telephone and three times face-to-face each year) who provided personal counseling and encouragement.
* Interactive technology (IT) - Study members had access to an interactive Web site on which they could record and track their exercise and calorie intake; set goals and monitor their progress toward them; and communicate with others in the IT group.
* Self-directed (SD) - Participants were urged to maintain their weight loss and then sent off without further intervention.

Results from the trial after 30 months included:

* Overall, 71 percent weighed less than when they began Phase I. The difference in the percentage of each group that weighed less was statistically significant - PC group (77 percent); IT group (69 percent) and SD group (67 percent).
* Thirty-seven percent of enrollees weighed at least 5 percent below their beginning weight. Again, the PC participants (42 percent) significantly out-performed those in the SD (34 percent) and IT (29 percent) groups.
* Among all study members, 32 percent weighed no more than 3 percent above their weight at randomization. However, differences between the three groups - SD (29 percent), IT (29 percent) and PC (36 percent) - were not significantly different statistically.
* Although at 24 months the average weight regained by the IT group was less than that of the SD arm, researchers found no difference between the two at 30 months.

"The effects we observed were modest," Svetkey said. "The personal contact group regained about 3.3 pounds less than the self-directed group."

Even a small weight loss can have potential health benefits, she noted.

"Each pound of weight loss can lower blood pressure by as much as a millimeter of mercury, and the more weight you lose, the bigger the blood pressure effect," Svetkey said. "Each pound of weight loss is estimated to lower the risk of developing diabetes by 8 percent, which is quite impressive.

"Clearly more research is needed to refine these maintenance interventions to make them more effective, but this study is an important step in the right direction."

American Heart Association