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nondiabetic patients following RYGB surgery are typically quite modest compared with the presurgery condition (3). Moreover, there appear to be 2 discrete periods of improvement. The first is immediately after surgery, at which time hepatic, but not peripheral, S I improves in response to acute energy restriction (4-6), while greater, protracted weight loss appears to be more strongly associated with improved peripheral S I (7,8). Even with significant weight loss 1 year following RYBG surgery, peripheral S I is still low compared with that of lean metabolically healthy individuals (3,5,6,9).Exercise is considered a cornerstone for obesity treatment, and while it is not generally viewed to cause substantial body weight reduction (10), it can potently improve peripheral S I and glucose control (11-13) and can reduce the risk of T2D and cardiovascular disease (14,15). There is general consensus that even a single session of moderate intensity exercise can induce an improvement in S I (16). There is also evidence that exercise can BACKGROUND. Roux-en-Y gastric bypass (RYGB) surgery causes profound weight loss and improves insulin sensitivity (S I ) in obese patients. Regular exercise can also improve S I in obese individuals; however, it is unknown whether exercise and RYGB surgery-induced weight loss would additively improve S I and other cardiometabolic factors. METHODS.We conducted a single-blind, prospective, randomized trial with 128 men and women who recently underwent RYGB surgery (within 1-3 months). Participants were randomized to either a 6-month semi-supervised moderate exercise protocol (EX, n = 66) or a health education control (CON; n = 62) intervention. Main outcomes measured included S I and glucose effectiveness (S G ), which were determined from an intravenous glucose tolerance test and minimal modeling. Secondary outcomes measured were cardiorespiratory fitness (VO 2 peak) and body composition. Data were analyzed using an intention-to-treat (ITT) and per-protocol (PP) approach to assess the efficacy of the exercise intervention (>120 min of exercise/week).RESULTS. 119 (93%) participants completed the interventions, 95% for CON and 91% for EX. There was a significant decrease in body weight and fat mass for both groups (P < 0.001 for time effect). S I improved in both groups following the intervention (ITT: CON vs. EX; +1.64 vs. +2.24 min -1 /μU/ml, P = 0.18 for Δ, P < 0.001 for time effect). A PP analysis revealed that exercise produced an additive S I improvement (PP: CON vs. EX; +1.57 vs. +2.69 min

ObjectiveWe 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.MethodsNinety-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.ResultsPatients in the highest quartile of steps/day change lost more fat mass (FM) (3rd =−19.5kg and 4th=−22.7kg, P<0.05) and abdominal adipose tissue (− 4th=−313cm2, P<0.05);, maintained skeletal muscle mass (3rd = 3.1cm2 and −4th=−4.5cm2, 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 (R2 =73.8% and R2 =70.6%, respectively).ConclusionNon-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.

Objective Objective measurements of physical activity (PA), energy expenditure (EE) and energy intake can provide valuable information regarding appropriate strategies for successful sustained weight loss. Design and methods We examined total EE by doubly labeled water, resting metabolic rate, PA with activity monitors, and energy intake by the Intake/Balance technique in 116 severely obese undergoing intervention with diet alone (DO) or diet plus PA (D-PA). Results Weight loss of 9.6±6.8 kg resulted in decreased EE which was not minimized in the D-PA group. Comparing the highest and lowest quartiles of increase in PA revealed a lower decrease in TDEE (−122±319 vs. −376±305 kcal/d), elimination of the drop in AEE (83±279 vs. −211±284 kcal/d) and greater weight loss (13.0±7.0 vs. 8.1±6.3 kg). Increased PA was associated with greater adherence to energy restriction and maintenance of greater weight loss during months 7–12. Conclusion Noncompliance to prescribed PA in the DO and D-PA groups partially masked the effects of PA to increase weight loss and to minimize the reduced EE. Increased PA was also associated with improved adherence to prescribed caloric restriction. A strong recommendation needs to be made to improve interventions that promote PA within the context of behavioral weight loss interventions.