Reductions in whole-body fat mass but not increases in lean mass predict changes in cardiometabolic health indices with exercise training among weight-stable adults

Abstract

We assessed whether body composition changes with 9 months of exercise training predicted changes in cardiometabolic health indices in weight-stable adults. We hypothesized that within ±5% weight change, changes in whole-body fat and lean masses would predict changes in cardiometabolic health indices with exercise training. Using a randomized parallel design, 152 adults (age: 49 ± 8 year; body mass index: 30.0 ± 2.7 kg/m2; mean ± SD) performed resistance exercises 2 d/wk and aerobic exercises 1 d/wk for 9 months. Participants consumed isoenergetic supplements with 0, 10, 20, or 30 g whey protein twice daily and remained weight stable within ±5% of baseline weight. Body weight and composition were measured using dual-energy x-ray absorptiometry pre- and postintervention. Multiple linear regression model was applied for data analyses. Independent of whey protein supplementation, reductions in fat mass predicted increases in high-density lipoprotein cholesterol (unstandardized beta-coefficient [β], −0.03; 95% confidence interval [CI], −0.06 to −0.01; P = .007) and insulin sensitivity index (β, −0.52; 95% CI, −0.95 to −0.09; P = .018) and decreases in waist circumference (β, 0.67; 95% CI, 0.17-1.18; P = .009). In contrast, increases in lean mass did not predict changes in any of the measured cardiometabolic health indices. Health improvements with training that emphasize resistance exercises are typically attributed to increases in lean mass; however, these results underscore reducing body fat to predict cardiometabolic health improvements.