Drug Therapy and Lifestyle Modification for Weight Loss

What is the problem and what is known about it so far?
In order to get maximum therapeutic benefit, weight loss medications such as sibutramine are recommended as part of a program that includes diet, exercise, and behavior therapy. However, they are typically prescribed with little or no lifestyle changes. Also, the addition of lifestyle change has not been proven experimentally as most trials of weight loss medication have included limited programs of lifestyle modification.

Why did the researchers do this particular study?
Currently two drugs, sibutramine and orlistat are approved by the FDA for inducing and maintaining weight loss. This study was done to compare weight loss in people who were taking medication and had undergone lifestyle modification with those who were just taking medication.

Who was studied?
180 women and 44 men that were 18 to 65 years of age participated in the study. All the participants were obese (BMI = 30-45). None had uncontrolled hypertension; cerebrovascular, cardiovascular, kidney or liver disease or diabetes mellitus. Pregnant women, breastfeeding women, people with eating disorders and people on medications known to affect weight were excluded.

How was the study done?
Subjects were randomly assigned to one of four groups. The four groups were sibutramine alone, lifestyle modification alone, sibutramine plus brief lifestyle modification and sibutramine plus lifestyle modification. Subjects who were in the 3 groups that received sibutramine were given identical doses. Those in the brief lifestyle modification group met 8 times with their primary care provider on the same schedule as those receiving sibutramine. They were provided brief information on how to lead a healthy lifestyle during those 15 minute visits. However, participants in the lifestyle modification group attended weekly group meetings led by trained psychologists that followed the LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition) program for weight control, which instructed subjects to complete weekly homework assignments that included keeping daily records of food and calorie intake and physical activity. The subjects’ weights were measured over this 52 week study.

What did the researchers find?
Subjects that received both lifestyle modification counseling and sibutramine resulted in an average weight loss of 12 kg (26 lbs) at one year which was double the weight loss seen in groups receiving sibutramine alone or lifestyle modification counseling alone.

What were the limitations of the study?
It was not possible to identify the specific components of group lifestyle modification that contributed most to the increased weight loss when combined with sibutramine. Understanding this issue will require further studies.

What were the implications of the study?
This study strongly suggests that the best weight loss results will be obtained when medication is used in conjunction with changes in diet, exercise and behavior therapy. Further research is needed to determine the most effective method of providing lifestyle modification counseling in primary care and community settings.

Summarized by Carl Kapadia, College of Medicine, University of Vermont
Summarized from "Randomized Trial of Lifestyle Modification and Pharmacotherapy for Obesity." Waddon, T. et al. The New England Journal of Medicine, Nov 17, 2005, Volume 353, pages 2111-2120.