Whey protein supplementation in women produces modest increases in lean mass
Whey protein supplementation favourably affects body composition, inducing modest increases in lean mass but without causing changes in fat mass, according to a systematic review and meta-analysis. Body composition improvements are more pronounced when protein supplementation is combined with energy restriction.
Researchers searched multiple electronic databases for studies assessing the effects of whey protein supplementation with or without energy restriction and resistance training on body mass, lean mass and fat mass in women. A total of 13 randomized controlled trials, involving 488 adult female participants and 15 whey protein vs control comparisons, were included in the meta-analysis.
Pooled data revealed that whey protein supplementation modestly increased lean mass (weighted mean difference [WMD], 0.37 kg; 95 percent CI, 0.06–0.67) but did not induce changes in fat mass (MWD, −0.20 kg; −0.67 to 0.27) relative to nonwhey protein control.
The beneficial effect of whey protein on lean mass disappeared when only studies with resistance training were included in the analysis (seven comparisons; MWD, 0.23 kg; −0.17 to 0.63), but became more robust when only studies with an energy restriction component were included (six comparisons; MWD, 0.90 kg; 0.31–1.49).
Whey protein showed no effect on lean mass in studies without an energy restriction component (nine comparisons; MWD, 0.22 kg; −0.12 to 0.57).
According to researchers, the null effect of protein supplementation on fat mass and <1 percent increase in lean mass is not in line with the public perception that whey protein results in excessive hypertrophy or bulkiness in women. Whey protein may be more beneficial when included as part of a weight loss program.
The findings support consumption of whey protein in women seeking to modestly improve body composition, researchers said. Still, more work is needed to specifically assess the effects of supplementation with respect to varying states of energy sufficiency and exercise training.