Effects of whey protein supplementation and exercise training on body composition and indices of metabolic syndrome in middle-aged overweight and obese adults
Abstract
The rising prevalence of obesity and metabolic syndrome over the past few decades is a major public health concern and warrants strategies that successfully reduce these conditions in the longer-term. Consumption of diets high in total dietary protein as well as whey protein have been linked to improved body composition, blood pressure, lipid and lipoprotein profiles, and insulin sensitivity. Given the well documented benefits of exercise training on these components of metabolic syndrome, combining increased total protein intake via whey supplementation with exercise training may additively enhance improvements in these risk factors.^ This study assessed the effects of different quantities of whey protein on body composition, dietary compensation, and risk factors of metabolic syndrome in middle-aged overweight/obese adults who exercise trained. For this double-blind, randomized, placebo-controlled, community-based 9-month study men (n=87, aged 48±8 y, BMI 30.6±2.8 kg/m2) and women (n=133, aged 48±8 y, BMI 29.8±2.7 kg/m2; mean±SD) consumed 200 kcal supplements with 0 (n = 84), 10 (n = 81), 20 (n = 25), or 30 (n = 30) g whey protein twice daily (400 kcal/d with 0, 20, 40 and 60 g WP/d, respectively). All subjects performed resistance (2 d/wk) and aerobic (1 d/wk) exercise.^ Twenty-four-hour urinary urea nitrogen output was progressively higher with greater WP, consistent with increasing total protein intake (group-by-time, p=0.009). Whey protein supplementation did not influence the body composition and dietary compensation responses over time. Among all subjects, strength increased 15±12 % (p<0.001), VO2max increased 9±15 % (p<0.001), body weight was unchanged (p=0.8), lean body mass increased 1.9±2.8 % (p<0.001) and fat mass decreased -2.6±9 % (p=0.001). Non-supplement energy intake decreased 331±49 kcal/d (p<0.001) and total energy intake did not change from pre to post, thus the subjects maintained body weight by compensating for the 400 kcal/d supplements.^ Whey protein amount also did not influence the responses for indices of metabolic syndrome. Among all subjects, from pre to post glucose area under the curve (AUC) was unchanged (p=0.16), insulin AUC decreased 2.6±2.3% (p=0.01), and the homeostatic model assessment (p=0.81) and insulin sensitivity index (p=0.63) were unchanged. Furthermore, blood pressure decreased 2-3% (p<0.05) and plasma lipid lipoprotein profile (total, LDL and HDL cholesterol and triacylglycerol), C-reactive protein, and waist circumference were unchanged. ^ In conclusion, whey protein supplementation did not influence exercise-induced responses in strength, aerobic capacity, body composition and indices of metabolic syndrome in middle-aged overweight/obese adults who maintained body weight. This study demonstrates the success of a community-based aerobic and resistance exercise training intervention to positively influence fitness and body composition and promote metabolic health.^
Degree
Ph.D.
Advisors
Wayne W. Campbell, Purdue University.
Subject Area
Health Sciences, Nutrition|Health Sciences, Recreation
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