BACKGROUND: Obesity is related to asthma, but factors influencing this relation have not been clearly defined. OBJECTIVE: This study was designed to assess the role of eating behaviors and weight concerns in the association between obesity and asthma. DESIGN: A population-based sample of 11,710 adolescents, recruited from 186 secondary schools of 8 educational districts in France, completed a self-administered standardized questionnaire including DSM IV (Diagnostic and Statistical Manual of Mental Disorders) questions on eating disorders. RESULTS: Obesity (body mass index >/=95th percentile according to age and sex) was associated with asthma in girls (odds ratio: 1.48; 95% CI: 1.05, 2.08) but not in boys (odds ratio: 1.07; 95% CI: 0.75, 1.54). Both obese and asthmatic adolescents were more likely to have abnormal eating behaviors and weight concerns (P < 0.05). In an adjusted polytomous logistic model with 4 categories based on the presence and/or the absence of asthma and obesity as the dependent variable, the odds ratio for weight concerns increased from a minimum value for asthmatic nonobese adolescents (odds ratio: <1.5; P < 0.03) to a maximum value for asthmatic obese adolescents (odds ratio: >6.3; P < 0.001) with nonasthmatic, nonobese adolescents as the reference group. Similar patterns were observed for overweight. CONCLUSIONS: Our data suggest that, besides well-known factors such as genetic background, direct mechanical effects, and reduced physical activity, abnormal eating behaviors and weight concerns might intervene in the relation between obesity and asthma. Psychosocial dimension has to be considered to disentangle the complex relation between obesity and asthma in adolescence in view of prevention.