Effect of length of treatment on weight loss

In this study we tested whether the efficacy of behavior therapy for obesity might be improved by lengthening the duration of treatment. Forty-eight obese clients were randomly assigned to either a standard treatment of 20 weekly sessions or to an extended treatment of 40 weekly sessions. The content of each program was identical, but the treatment procedures were introduced in a more gradual manner in the extended condition. At Week 20, the conditions showed equivalent weight losses. At 40- and 72-week evaluations, however, the extended treatment produced significantly greater mean weight losses than did the standard treatment.