This study investigated whether implicit and self-reported food and exercise attitudes changed during a residential six month treatment period in youngsters with obesity (n=19). Moreover, it was examined whether this attitudinal change explained their decrease in overweight during the program and at a one year follow up. Two Extrinsic Affective Simon Tasks (EAST) were conducted to investigate implicit attitudes towards exercise and food, respectively. Self-reported attitudes were assessed using a questionnaire. The results revealed that the obese youngsters lost weight during the treatment, that was not regained at follow up. Mean self-reported and implicit attitudes did not change markedly. Moreover, changes in self-reported attitudes were not predictive for decrease in overweight during and after the treatment. In contrast, some small effects were found for the change in implicit attitudes towards food and exercise. Several possible explanations are discussed.