No abstract

Further research may enable psychological determinants to better guide weight loss theory and treatments.

The behavioral processes of weight reduction are poorly understood, and responses to treatments based primarily on caloric restriction have been unfavorable. A theory-based path derived from proposed relations of physical activity, changes in psychological factors, and weight loss was separately tested with women with Class I and Class II obesity (body mass index [BMI] from 30 to 39.9 kg/m(2); n = 116), and Class III (BMI > or = 40.0 kg/m(2); n = 57) obesity. Participation in a cognitive-behavioral exercise support treatment along with nutrition education was significantly associated with changes in measures of self-efficacy, body satisfaction, and mood. Changes did not significantly differ by BMI group. Multiple regression analyses indicated that changes in the psychological factors explained 14% (Class I/II obesity group) and 22% (Class III obesity group) of the variance in exercise session attendance, and attendance was strongly related to weight loss. Implications for weight loss theory and treatment are discussed.