Behavioral and psychological factors associated with 12-month weight change in a physical activity trial

Examining behavioral and psychological factors relating to weight stability over a 1-year period is of public health importance. We conducted a physical activity (PA) intervention trial for women (N = 247; mean age = 47.5 ± 10.7; mean BMI = 28.6 ± 5.3) in which participants were assigned to one of three groups (two PA and one contact-control). By Month 12, participants achieved 140.4 ± 14.82 min of PA/week, with no group differences. Weight status change from baseline to Month 12 was categorized: no change (N = 154; 62.4%); increase (N = 34; 13.8%); decrease (N = 59; 23.9%). Discriminant function analyses indentified two statistically significant dimensions associated with weight change. Dimension 1 was positively weighted by mood (0.73) and self-efficacy (0.79); dimension 2 was positively weighted to change in physical activity (0.58) and fat consumption (0.55). Results provide further evidence for the importance of behavior in long-term weight maintenance, particularly physical activity and dietary fat. These findings also provide evidence for the importance of addressing psychosocial variables, in particular depressed mood and self-efficacy.