Randomized Trial Reveals that Physical Activity and Energy Expenditure are associated with Weight and Body Composition after RYGB

OBJECTIVE: We investigated the associations of both physical activity time (PA) and energy expenditure (EE) with weight and fat mass (FM) loss in patients following Roux-en-Y gastric bypass (RYGB) surgery. METHODS: Ninety-six non-diabetic patients were included in this analysis. Post RYGB patients were randomized in one of two treatments: A 6-month exercise training program (RYBG+EX) or lifestyle educational classes (RYGB). Body composition was assessed by dual-energy X-ray absorptiometry and computed tomography. We quantified components of PA and EE by a multisensory device. We explored dose-response relationships of both PA and EE with weight loss and body composition according to quartiles of change in steps/day. RESULTS: Patients in the highest quartile of steps/day change lost more fat mass (FM) (3(rd) =−19.5kg and 4(th)=−22.7kg, P<0.05) and abdominal adipose tissue (− 4(th)=−313cm(2), P<0.05);, maintained skeletal muscle mass (3(rd) = 3.1cm(2) and −4(th)=−4.5cm(2), P<0.05) and had greater reductions in resting metabolic rate. Decreases in sedentary EE, increases in Light EE and age were significant predictors of both Δweight and ΔFM (R(2) =73.8% and R(2) =70.6%, respectively). CONCLUSION: Non-diabetic patients who perform higher - yet still modest - amounts of PA following RYGB have greater energy deficits, lose more weight and body fat mass, while maintaining higher skeletal muscle mass.