Dynamic relations between sedentary behavior, physical activity, and body composition after bariatric surgery.

ABSTRACT

BACKGROUND: Physical activity has been shown to increase following obesity surgery; however, changes in sedentary behavior in this setting are not known. Our aim was to describe changes in both physical activity and sedentary behavior of obese patients after gastric bypass (GBP) and their relationships with changes in body composition. METHODS: Physical activity, time spent watching TV as typical sedentary behavior (self-report), and body composition (DXA) were assessed before and 6 and 12 months after GBP in 86 obese patients (67 women, 24-66 years old, BMI 41.3-53.5 kg/m(2)). RESULTS: One year after GBP (mean loss of weight -37.1 kg, fat mass -25.7 kg, lean body mass -9.4 kg), leisure-time physical activity (LTPA) significantly increased from 2.0 (SD 3.7) to 3.8 (5.4) h/week and from 7.2 (12.5) to 14.1 (20.1) MET-h/week (MET metabolic equivalent task), the number of LTPA performed increased from 1.3 (1.3) to 1.8 (1.4), and TV time decreased from 3.0 (1.6) to 2.4 (1.4) h/day (all p < 0.05). The ranking of the most frequently performed LTPA did not change. Positive associations were observed between the increase in lean body mass and (1) the increase in LTPA and (2) the decrease in TV watching. Inverse relationships were found for changes in fat mass. CONCLUSIONS: Together with increased LTPA, this study shows a decrease in sedentary behavior after GBP, which appears related to favorable changes in body composition. These observations are important to design future intervention studies, including physical activity and sedentary occupations aiming to optimize the care of patients after bariatric surgery.