Although research indicates that treatment-induced improvements in self-regulation, mood, and self-efficacy significantly predict increased exercise and improved eating, moderation by participants' personal characteristics is largely unknown. Severely obese adults (N = 414; 47% White, 53% African American) volunteered for a behavioral exercise and nutrition treatment and demonstrated significant within-group improvements in self-efficacy for exercise, self-regulation for exercise, mood, self-efficacy for controlled eating, self-regulation for controlled eating, exercise volume, and fruit and vegetable intake over 26 weeks. After testing age, sex, and race/ethnicity as possible moderators of the prediction of changes in exercise volume and fruit and vegetable consumption by changes in self-regulation, mood, and self-efficacy, only age significantly moderated change in volume of exercise. Implications for theory and treatment were discussed.