Nov. 17, 2005 A new study shows that treatment with a lifestyle modification program of diet, exercise and behavioral therapy when used in combination with the weight loss medication sibutramine (Meridia®) resulted in significantly greater weight loss among obese adults than treatment with the medication alone. The study, conducted by researchers from the University of Pennsylvania, appears in the November 17, 2005 issue of The New England Journal of Medicine and was supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), one of the National Institutes of Health (NIH).
"Lifestyle modification should be the first line of treatment for obesity," says Susan Yanovski, M.D., director of the Obesity and Eating Disorders Program for NIDDK, and author of an accompanying editorial in the journal. "But for obese adults who can't lose enough weight to improve their health, medication used as an adjunct can help."
"The take home message is that weight loss medications will be most effective when they are combined with a reduced calorie diet and increased physical activity," says Thomas A. Wadden, Ph.D., Professor of Psychology in the Department of Psychiatry at the University of Pennsylvania School of Medicine, and lead author of the study. "Weight loss medication used alone can produce some weight loss, but lifestyle modification treatment can help patients acquire skills to successfully make changes in their diet and physical activity."
A total of 224 obese adults aged 18 to 65 years participated in the one-year study. Participants were randomly assigned to one of four groups: 1. weight loss medication alone; 2. lifestyle modification alone; 3. weight loss medication plus lifestyle modification; and 4. weight-loss medication plus brief physician-mediated therapy. The researchers included the fourth treatment group to measure the effectiveness of weight-loss medication combined with brief lifestyle modification counseling delivered by primary care providers. The researchers looked at this type of therapy as a possible model for delivering lifestyle modification therapy in the setting of primary care practice.
Participants in the lifestyle modification therapy group attended a total of 30, 90-minute group meetings. During the meetings participants were instructed to complete and share weekly assignments, which included keeping detailed daily food and physical activity records. Participants in the brief lifestyle modification counseling group met with primary care physicians eight times for 10 to 15 minute visits, where they were given homework assignments, which also included keeping daily food and activity records. Participants in the weight-loss medication therapy alone group also met with primary care physicians eight times for 10 to 15 minute visits, but were not instructed to keep food or activity records and were provided only general information on diet and exercise. Those participants in the combined therapy group received both the lifestyle modification therapy and the weight-loss medication. All groups were prescribed a 1200 to 1500 calorie diet and the same exercise plan.
After one year, patients in the weight-loss medication plus lifestyle group lost an average of more than 26 pounds – more than double the weight loss seen with medication alone (11 pounds). In addition, 73 percent of participants in the combined therapy group lost 5 percent or more of their initial body weight, compared to 56 percent of participants in the brief therapy plus weight-loss medication group, 53 percent of participants in the lifestyle modification alone group, and 42 percent of participants in the weight-loss medication alone therapy group. More than half or 52 percent of people in the combined therapy group lost 10 percent or more of their initial body weight compared to 29 percent of participants in the lifestyle modification alone group, 26 percent of participants in the brief therapy plus weight-loss medication group, and 26 percent of participants in the weight-loss medication alone group.
Interestingly, those participants in the combined therapy group who were most successful were those who frequently recorded their food intake. Those participants with high adherence to food intake record keeping lost more than twice as much weight as those with low adherence (41.5 versus 17 pounds).
"Some people have questions about how they can do lifestyle modification," says Dr. Wadden. "I think that a first step is to complete daily food logs. Food records help people become aware of their eating patterns and identifying areas for improvement." Dr. Wadden adds that the second step to weight loss is to increase physical activity and one of the best ways to do that is to obtain a pedometer to count steps and gradually increase daily walking.
One limitation of the study is that it only included obese patients who were otherwise healthy and excluded obese patients with health problems possibly related to their obesity, such as hypertension, cardiovascular disease, cerebrovascular disease, kidney disease, liver disease, and diabetes. Because many obese patients also have other conditions that can adversely affect their health, physicians should carefully monitor patients enrolled in weight-loss programs that include weight-loss medications.
The findings of the study are consistent with the NIH Obesity Clinical Guidelines, which recommend that weight loss medications be used in a supportive role to a comprehensive program of behavioral treatment, diet therapy, and increased physical activity. The NIH Obesity Clinical Guidelines state that the most successful strategies for weight loss include calorie reduction, increased physical activity, and behavioral therapy designed to improve eating and physical activity habits. The Guidelines also recommend that physicians prescribe a regimen of lifestyle therapy for at least six months before adding weight-loss medication to the regimen. More information on the NIH Obesity Clinical Guidelines is available on the NIH web site at http://www.nhlbi.nih.gov/guidelines/obesity/ob_home.htm.
According to data from the 1999 to 2000 National Health and Examination Survey (NHANES), approximately 65 percent of Americans aged 20 years or older are overweight with 31 percent of adults obese as defined by body mass index (BMI). BMI is a calculation that takes into account both height and weight. Overweight is defined as having a BMI of 25 to 29.9 kg/m2. Obesity is defined as having a BMI of 30 kg/m2 or higher. The NIDDK Weight-control Information Network fact sheet, Statistics Related to Overweight and Obesity (http://win.niddk.nih.gov/statistics/index.htm) provides more information.
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