Individual and school environment factors associated with overweight in adolescents of the municipality of Rio de Janeiro, Brazil

Objective: To identify the association of individual and school environment factors with overweight among adolescents. Design: Cross-sectional study. Sociodemographic and behavioural information was collected using an anonymous self-administered questionnaire. Indicators on human and physical resources of the schools were based on information collected in interviews with school principals. Overweight was defined based on the BMI Z-score for age and sex recommended by WHO. Logistic regression models were used for statistical analysis. Setting: Rio de Janeiro, Brazil. Subjects: By means of a two-stage (classrooms and students) probabilistic sampling, subjects comprised 1632 students enrolled in the last year of primary education of the municipal public school network, stratified by city region. Results: The mean prevalence of overweight at schools was 17.2%, ranging from 0% to 50%. Adolescents more likely to be overweight were those who attended schools without knives and forks or ceramic/glass plates for students in the school refectory (prevalence odds ratio (POR) = 1.40; P = 0.04), those whose head of household had completed between 8 and 10 years of schooling (POR = 1.46; P = 0.03), those who did not live with both parents (POR = 1.24; P = 0.06) and those who had not practised physical activity outside school on at least 1 d in the 7 d before the study (POR = 1.56; P = 0.04). Conclusions: Sociodemographic and behavioural variables of adolescents and school characteristics were associated with overweight, confirming individual and context effects on this health disorder. Studies such as the present one, identifying variables in context, may support actions to prevent overweight among adolescents.