This project holds unique characteristics which comply with the latest recommendations for the treatment of adolescent obesity, and others that we have not been able to find in the literature: a) the inclusion of peers explicitly on the treatment protocol; b) the clinical setting of the treatment, with "real-life" subjects; c) objective measurements of the outcomes; d) the long-term treatment; and e) a well established rational (SDT and experiential learning) for the behavior change and to analyze the causal relations between predictors and outcomes.