Whey Protein Supplementation Does Not Affect Exercise Training-Induced Changes in Body Composition and Indices of Metabolic Syndrome in Middle-Aged Overweight and Obese Adults

Little is known about the effects of different quantities of whey protein on exercise training-induced changes in body composition and indices of metabolic syndrome in middle-aged overweight and obese adults. Therefore, we examined the effects of consuming 0.8-MJ supplements with 0 (n = 126), 10 (n = 112), 20 (n = 44), or 30 (n = 45) g whey protein twice daily in conjunction with resistance (2 d/wk) and aerobic (1 d/wk) exercise training in a double-blind, randomized, placebo-controlled, community-based 9-mo study in men (n = 117) and women (n = 210); (age: 48 +/- 7.9 y; BMI: 30.0 +/- 2.8 kg/m(2)). Whey protein supplementation did not influence any of the following outcomes, some of which were affected by training. Among all participants, strength increased by 15 +/- 12% (P < 0.001) and maximal oxygen uptake capacity (VO(2)max) increased by 9 +/- 15% (P < 0.001). Body weight was unchanged (0.1 +/- 3.7 kg, P = 0.80), lean body mass increased by 1.9 +/- 2.8% (0.95 +/- 1.3 kg, P < 0.001), and fat mass decreased by 2.6 +/- 9.4% (-0.86 +/- 3.1 kg, P = 0.001). Oral-glucose-tolerance testing showed that plasma glucose AUC was unchanged (-18.0 +/- 170 mmol/L . 3 h, P = 0.16), insulin AUC decreased by 2.6 +/- 32% (-7.5 +/- 29 nmol/L . 3 h, P = 0.01), and HOMA-IR (0.2 +/- 2.0, P = 0.81) and the insulin sensitivity index (0.3 +/- 3.0, P = 0.63) were unchanged. Plasma concentrations of TG; total, LDL, and HDL cholesterol; C-reactive protein; plasminogen activator inhibitor-1; blood pressure; and waist circumference were unchanged. Whey protein supplementation did not affect exercise training-induced responses in body composition and indices of metabolic syndrome in middle-aged overweight and obese adults who maintained body weight. J. Nutr. 142: 1532-1539, 2012.