A new study has found that 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 Meridia alone.

Results of the study by researchers from the University of Pennsylvania are reported November 17, 2005 in The New England Journal of Medicine.

Thomas A. Wadden, a professor at the University of Pennsylvania School of Medicine and lead author of the study, said "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.

"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," Wadden added.

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.

All groups were prescribed a 1,200 to 1,500 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," said 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."

Wadden said 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 was 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.