Randomized trial reveals that physical activity and energy expenditure are associated with weight and body composition after RYGB

Abstract

Objective: This study 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 nondiabetic 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. Components of PA and EE were quantified by a multisensory device. Dose-response relationships of both PA and EE with weight loss and body composition were explored according to quartiles of change in steps per day.

Results: Patients in the highest quartiles of steps per day change lost more FM (3rd = -19.5 kg and 4th = -22.7 kg, P < 0.05) and abdominal adipose tissue (4th = -313 cm2 , P < 0.05), maintained skeletal muscle mass (3rd = -3.1 cm2 and 4th = -4.5 cm2 , P < 0.05), and had greater reductions in resting metabolic rate. Decreases in sedentary EE and increases in light EE and age were significant predictors of both Δweight and ΔFM (R2 = 73.8% and R2 = 70.6%, respectively).

Conclusions: Nondiabetic patients who perform higher, yet still modest, amounts of PA following RYGB have greater energy deficits and lose more weight and FM, while maintaining higher skeletal muscle mass.

Trial registration: ClinicalTrials.gov NCT00692367.

Conflict of interest statement

Conflict of Interest: JMJ conflicts of interest: Scientific Advisor for Weight Watchers International; Coinvestigator on a research grant awarded to the University of Pittsburgh by Weight Watchers International; Co-investigator on a research grant awarded to the University of Pittsburgh by HumanScale. The other authors report no conflicts of interest.

© 2017 The Obesity Society.

Figures

Figure 1

Flowchart of participant recruitment, screening and assessment. Inclusion criterion for physical activity analysis are also included. Modified from Coen et al. (12).

Figure 2

Change in non-exercise related physical activity (NEPA) after 6-months of an exercise training program (RYGB+EX) or educational program (RYGB) in patients whom underwent Roux-en-Y gastric bypass. Means adjusted to pre intervention values. Error bars are one standard deviation. ** and ***, indicate P

Figure 3

Changes in body composition variables by quartiles of daily steps change (post-pre intervention, higher quartile larger increase in PA level): 1st Q, first quartile (−1,419 steps/day), 2nd Q, second quartile (402 steps/day), 3rd Q, third quartile (1,618 steps/day) and 4th Q, fourth quartile (3,446 steps/day). FM, fat mass from dual X-ray absorptiometry (DEXA); AT, adipose tissue; IMAT, intramuscular AT. AT, IMAT and skeletal muscle mass were measured by computed tomography scans (CT). *, Ppost hoc test (bars are means adjusted for pre intervention values, age, randomization time and weight at pre surgery). ^, significant trend from general lineal model.

Figure 4

Simple correlations between change in weight and measures of physical activity (PA) and energy expenditure as measured by device which combine a 3-axes accelerometer and temperature sensors (SenseWear Armbamd). TDEE, total daily energy expenditure; SedEE, energy expenditure during sedentary time; NetTDEE = TDEE – resting metabolic rate (RMR); NetSedEE = SedEE – RMR; TDPA, total daily PA including light, moderate ad vigorous dimensions; STEPs, number of steps per day.

Figure 5

Scatter plots between measured and predicted changes in weight (white dots) or fat mass (FM, black dots). Predicted values were estimated from regression models from absolute changes in energy expenditure (EE) variables (A), changes in Net EE variables (B) and changes in physical activity (PA) dimensions (C).