S1 Data -

Background
Healthy diet and physical activity self-management is important in maintaining weight loss and preventing weight regain after bariatric surgery. We aimed at evaluating covariates of healthy diet and physical activity self-management among patients undergone bariatric surgery using Health Action Process Approach (HAPA) model.
Method
In this cross-sectional study, 272 patients with a history of bariatric surgery were selected from the data registry of Tehran Obesity Treatment Study (TOTS). Data were collected using bariatric surgery self-management standard questionnaire (BSSQ), and items based on HAPA model for healthy diet and physical activity self-management. Data were analyzed using Path analysis and AMOS version 24.
Results
The mean score of self-management was (32 ± 10SD). Coping planning construct (β = 0.22; p<0.001) and risk perception (β = 0.02; p<0.01) in dietary self-management and action planning (β = 0.16; p = 0.001) and risk perception (β = 0.001; p = 0.17) in physical activity self-management had the highest and lowest effect powers, respectively. Coping planning (β = 0.22; p<0.001) and action planning (β = 0.17; p<0.03) in diet, and action planning (β = 0.16; p = 0.010) in physical activity were significantly related to self-management. Also, task-coping self-efficacy (β = 0.28; and p<0.001), outcome expectancies (β = 0.37; p<0.001), risk perception (β = 0.13; p = 0.015) in diet and coping self-efficacy (β = 0.50; p<0.001), outcome expectancies (β = 0.12; p = 0.021) in physical activity were significantly related to behavioral intention. The values of CFI = 0.939 and RMSEA = 0.052 for diet and CFI = 0.948 and RMSEA = 0.048 for physical activity indicated adequate fit.
Conclusion
HAPA was applicable as a framework for interventions promoting healthy diet and physical activity self-management in patients who have undergone bariatric surgery.