The Interplay among BMI z-Score, Peer Victmization, and Self-Concept in Outpatient Children and Adolescents with Overweight or Obesity.

Background: Research has provided evidence that obesity is associated with peer victimization and low levels of self-concept. No study has examined the relationship between BMI z-score, self-concept in multiple domains, and peer victimization. Methods: The aim of the research was to investigate the interplay between BMI z-score, self-concept in multiple domains (physical, athletic, social), and peer victimization, testing direct, mediated, and moderated associations. Eighty hundred fifteen outpatient children and adolescents were consecutively recruited in 14 hospitals distributed over the Italian country. The sample consisted of 419 males and 396 females; mean age 10.911.97 years (range 6-14 years) and mean BMI z-score 1.850.74 (range -0.97 +/- 3.27). Peer victimization and self-concept were assessed with a revised Olweus Bully/Victim Questionnaire and with the Self-Perception Profile for Children. A structural equation model approach was used to determine the associations among variables, testing two competing models. Results: In both models, path analysis revealed that BMI z-score was directly associated with peer victimization and self-concept in multiple domains. In the first model, peer victimization mediated the relationship between BMI-score and self-concept, whereas in the alternative model, self-concept mediated the relationship between BMI z-score and peer victimization. Interaction analyses revealed that social competence moderated the relationship between BMI z-score and peer victimization and that peer victimization moderated the relationship between BMI z-score and physical appearance. Conclusions: Higher levels of BMI z-score are a risk factor for peer victimization and poor self-concept. When high levels of BMI z-score are associated with a negative self-concept, the risk of victimization increases. Preventive and supportive interventions are needed to avoid negative consequences on quality of life in children and adolescents with obesity.