Predictors of Physical Activity After Gastric Bypass-a Prospective Study

Most patients do not meet the recommended level of physical activity after bariatric surgery, and psychological factors underlying postoperative physical activity remain poorly understood. This study aimed at identifying self-regulatory predictors of physical activity after bariatric surgery.

Questionnaire data including self-regulation variables and the short-version of the International Physical Activity Questionnaire were obtained in a prospective cohort of 230 patients 1 year after Roux-en-Y gastric bypass. The study sample consisted of participants consenting to wear an ActiGraph GT3X+ accelerometer for seven consecutive days, 18-24 months after surgery (n = 120).

A total of 112 participants with complete self-report data provided valid accelerometer data. Mean age was 46.8 years (SD = 9.3), and 81.3% was women. Preoperative and postoperative BMI was 44.8 ± 5.5 and 30.6 ± 5.0 kg/m², respectively. Total weight loss was 28.9% (SD = 7.5). By objective measures, 17.9% of the participants met the recommended level of moderate-to-vigorous-intensity of physical activity of ≥150 min/week, whereas 80.2% met the recommended level according to self-reported measures. Being single, higher education level, and greater self-regulation predicted objective physical activity in multivariate regression analysis. Greater self-regulation also predicted self-reported physical activity. Weight loss 1 year after surgery was not associated with self-reported or objectively measured physical activity.

Despite large differences between accelerometer-based and subjective estimates of physical activity, the associations of self-regulatory factors and weight loss with postoperative physical activity did not vary depending on mode of measurement. Self-regulation predicted both objective and self-reported physical activity. Targeting patients' self-regulatory ability may enhance physical activity after gastric bypass.