Until recently, treatment of obesity was limited to counseling for lifestyle modification (e.g., encouraging patients to diet and exercise). Sibutramine (Meridia), a drug that assists with weight loss by modifying sensations of hunger and fullness, now may be administered as an adjunct or an alternative to counseling. However, data on sibutramine's effectiveness compared with counseling are limited, and it is uncertain if combining medication and lifestyle modification produces more weight loss than either therapy alone. Wadden and colleagues conducted a randomized controlled trial to examine the effectiveness of sibutramine and counseling for weight loss in obese but otherwise healthy adults.
The study population consisted of 224 adults (180 women, 44 men) with body mass indexes (BMIs) between 30 and 45 kg per m2 who wanted to lose weight. Patients were excluded if they or their family physicians reported the presence of uncontrolled hypertension, diabetes, cardiovascular or cerebrovascular disease, pregnancy and breastfeeding, or psychiatric problems. At the study's onset, all participants were encouraged to walk for 30 minutes every day and to consume a balanced diet of 1,200 to 1,500 kcal per day.
Participants were randomized to receive one of four treatments: sibutramine alone, lifestyle modification counseling alone, sibutramine plus counseling, or sibutramine plus brief counseling. Participants in the lifestyle modification and combined therapy groups attended 90-minute weekly group meetings led by trained psychologists for 18 weeks, followed by biweekly meetings through week 40 and a single follow-up visit at week 52. These participants recorded food and caloric intake and physical activity in daily logs. In contrast, brief counseling consisted of eight 10- to 15-minute visits with primary care physicians over one year. Participants assigned to sibutramine alone met with physicians the same number of times as those in brief counseling but were not given specific weight loss advice and were not asked to keep logs. Of the 224 participants, 185 (83 percent) completed the study protocol. All participants were included in the intention-to-treat analysis, except for two women who dropped out of the study because of preexisting pregnancies.
The primary outcome measures were average weight loss and the percentage of patients who lost 5 percent or more of initial weight. Although the sibutramine group had an average weight loss of 11 lb (5.0 kg, with 42 percent of patients losing more than 5 percent of their initial weight), this was markedly less than the lifestyle modification counseling group (14.7 lb [6.7 kg] and 53 percent), sibutramine plus brief counseling group (2.2 lb [7.5 kg] and 56 percent), and combined therapy group (26.6 lb [12.1 kg] and 73 percent). Increasing adherence was associated with increasing degrees of weight loss in groups that kept daily logs. There were no significant differences in adverse events among the groups, and all groups demonstrated reductions in total cholesterol, triglycerides, and insulin levels.
The authors conclude that combined therapy with sibutramine and lifestyle modification counseling is the most effective means to promote weight loss in otherwise healthy adults who are obese. Brief counseling by physicians plus sibutramine also was effective until week 18. The authors recommend that future studies examine the cost-effectiveness of obesity treatments.