Whey Protein Supplementation Does Not Affect Exercise Training–Induced Changes in Body Composition and Indices of Metabolic Syndrome in Middle-Aged Overweight and Obese Adults1–4

Abstract

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/m2). 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 (VO2max) 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.