['To determine the longitudinal relation between history of adult obesity and the 6-year trajectory of weight change in men.', 'Subjects were healthy, affluent men (n = 761) between the ages of 20 and 78 years who completed at least four comprehensive medical exams at the Cooper Clinic between 1987 and 2003. Maximum adult weight was reported, and current height was measured at baseline. Body weight and cardiorespiratory fitness were measured at all examinations. Adult obesity status was determined from self-reported maximum weight and measured height at baseline as BMI > or = 30 kg/m(2). Weight at all examinations was regressed on a history of adult obesity using linear mixed effects modeling.', 'At baseline, men reporting a history of adult obesity were significantly heavier than men reporting no such history (BMI 29.8 vs. 25.0 kg/m(2); p < 0.05). However, the rate of weight gain among men with a history of obesity was slower than among men without a history of adult obesity (0.04 vs. 0.18 kg/yr; p = 0.09), although this difference was only marginally significant. Fitness modulated the relationship between history of obesity and weight change over time, and both higher levels of fitness and greater frequency of dieting were associated with attenuated weight gain. In contrast, chronic disease and depression were associated with accelerated weight gain.'] Does adult obesity predict 6-year weight gain in men : the Aerobics Center Longitudinal Study?