Objective: To evaluate the effects of energy restriction with or without aerobic exercise on thigh muscle mass and quality in adults with visceral adiposity. Methods: 75 males and females were randomly assigned to the groups 'diet only' (DO; n = 42) or 'diet plus aerobic exercise' (D/Ex; n = 33) for 12 weeks. The target energy intake in both groups was 25 kcal/kg of ideal body weight. Subjects in the D/Ex group were instructed to exercise for >= 300 min/week at lactate threshold. Computed tomography was used to measure thigh muscle cross-sectional area (CSA), normal-density muscle area (NDMA), and visceral fat area. Results: Total body weight (DO: -6.6 +/- 3.6%; D/Ex: -7.3 +/- 4.6%) and visceral fat (DO: -16.0 +/- 13.8%; D/Ex: -23.1 +/- 14.7%) decreased significantly in both groups; however, the changes were not significantly different between the two groups. The decrease in muscle CSA was significantly greater in the DO group (-5.1 +/- 4.5%) compared with the D/Ex group (-2.5 +/- 5.0%). NDMA decreased significantly in the DO (-4.9 +/- 4.9%) but not in the D/Ex group (-1.4 +/- 5.0%). Conclusion: Aerobic exercise attenuated the loss of skeletal muscle during energy restriction in adults with visceral adiposity. (C) 2014 S. Karger GmbH, Freiburg