The aim of this study is to describe the psychological factors among young people treated for obesity and their parents. 63 families whose children (from 8 to 18 years old) are treated for weight problems have answered questions about the personality and the advantages/disadvantages of a healthy diet and regular exercise. Parents provided information on a scale of anxiety\textendashdepression, and on social demographic details. Young people have expressed their feelings of perceived competence, ability and motivation in the areas of nutrition and physical activity across different scales. A semi-structured interview was conducted with 13 families. Motivation and feeling of perceived competence in young people are high despite the important disadvantages to having a healthy diet. They have high scores in all dimensions of personality and there are correlations with the scores of perceived competence. Parents seem to be an important model from a personal hygiene point of view; however, no statistical relationship could be demonstrated with being overweight, anxiety or depression parents. (PsycINFO Database Record (c) 2013 APA, all rights reserved). (journal abstract)