Path analysis of exercise treatment-induced changes in psychological factors leading to weight loss.

Physical activity may affect weight loss largely through psychological pathways associated with eating changes, especially in obese individuals whose caloric expenditure through exercise is typically small. Direct testing of this is, however, lacking. Previously sedentary adults (N = 114; 77% female; M(age) = 43.3 years), with a minimum body mass index (BMI) of 35 kg/m² (M (BMI) = 42.0 kg/m²), participated in a 24-week treatment of cognitive-behavioural exercise support and nutrition information. A path model based on tenets of social cognitive and self-efficacy theory was constructed. It was expected that improvements in self-efficacy, physical self-concept, body satisfaction and mood associated with the exercise treatment would predict changes in self-regulation and increased physical activity. It was also hypothesised that improvements in self-efficacy and self-regulation for appropriate eating would transfer from these relationships and predict weight loss. After three theoretically viable paths were added based on modification indices, structural equation modelling indicated a good fit with the data, χ²(16) = 20.53, p = 0.20; RMSEA = 0.05; SRMR = 0.06; CFI = 0.97; TLI = 0.95. Associations of psychological effects linked to exercise programme participation with predictors of appropriate eating and weight loss were found, and may inform theory, research and treatments.