Objective: To identify lifestyle and sociodemographic risk factors of overweight among male college students. Design: A retrospective cohort study. Setting: Annual health checkup in a single university in Japan. Participants: Male students who underwent two successive health checkups from their third school year between 2000 and 2007 and whose BMI at baseline of this study was 22?0 kg/m 2 or more (n 4634). Results: During the 1-year follow-up, 598 students (12?9 %) reached the study endpoint, i.e. more than a 5 % increase in BMI. Conclusion: These data suggest that avoidance of certain risk factors in college life is associated with a decrease in incidence of overweight among male students.