The goal of the proposed research is to improve the treatment of obesity, a significant health hazard, by major innovations in therapeutic technique and by multidisciplinary study of the pathogenesis and possible etiology of obesity. The first specifc aim of the therapeutic endeavors is to improve the effectiveness of behavioral treatment of adult obesity by four means: (1) combining behavior therapy with very low calorie diet to increase the weight loss over that achieved in traditional programs, (2) developing an intensive behavioral program designed for the first time to focus on maintenance of weight lost with the help of the very low calorie diet, (3) testing the efficacy of this new treatment program against traditional behavioral and dietary programs in a large-scale trial, and (4) developing predictors of outcome of treatment through intensive physiological and psychological assessment procedures. Studies of pathogenesis and possible etiology of obesity include: (1) a study of the caloric intake and output of obese girls, following up our earlier demonstration of increased caloric intake and no decrease in caloric output among obese boys and (2) assessment of the role of endogenous opiates in food intake and anxiety reduction of obese humans.