BACKGROUND: Psychiatric disorders and being overweight are major health problems with increasing prevalence. The purpose of this study was to test the hypothesis that being overweight is associated with a range of psychiatric conditions including minor and atypical depressive disorders, binge eating, and aggression. METHOD: Prospective community-based cohort study of young adults (n = 591) followed between ages 19 and 40. Information derived from six subsequent semi-structured diagnostic interviews conducted by professionals over twenty years. Outcomes were being overweight [body-mass index (BMI)> 25] and average yearly weight change between ages 20 and 40 (BMI slope). RESULTS: 18.9 % of the participants were classified as being overweight. Being overweight turned out to be a stable trait: 77.7% of subjects were assigned to the same weight class at each interview. Atypical depression and binge eating were positively associated with both, increased weight gain and being overweight, while psychiatric conditions associated with aggressive behaviors (aggressive personality traits, sociopathy) were positively associated with being overweight, but were not related to the rate of weight change. Generalized anxiety disorder was negatively associated with overweight. These results persisted after controlling for substance use, levels of physical activity, demographic variables and family history of weight problems. CONCLUSIONS: This study shows relatively strong associations between eating-related and aggressive psychopathology and being overweight. Given the high prevalence rates of these conditions, this study encourages further research on the causality of psychopathology-overweight associations that might provide insight on novel preventive approaches for major health problems.