Poster Topical Area: Energy and Macronutrient Metabolism
Location: Hall D
Poster Board Number: 412
Objectives: Whey protein (WP) supplementation is promoted to help women improve their body composition, especially when consumed in conjunction with energy restriction (ER) and (or) resistance training (RT). However, a perception exists that women should not consume WP supplements because it could make them "bulky" (i.e. excessive lean mass accretion, which includes skeletal muscle). While results from individual research studies do not support the notion that WP supplementation makes women "bulky", a systematic assessment of the issue is needed. The purpose of this research is to assess the effect of WP supplementation on body composition changes over time in adult women. A systematic review and meta-analysis of literature was conducted to specifically determine the effect of WP supplementation in a 2x2 factorial fashion; with or without ER and with or without RT.
Methods: Pubmed, Scopus, Cochrane, and CINAHL were systematically searched. Two researchers independently screened 1845 abstracts and extracted 276 articles. Thirteen randomized controlled trials (resulting in 15 comparisons) with 28 groups met all inclusion criteria.
Results: Globally, WP supplementation increased lean mass (WMD 0.37 kg; 95%CI= 0.06 to 0.67) while not influencing changes in fat mass (-0.20 kg; 95%CI= -0.67 to 0.27) relative to non-WP control. The beneficial effect of WP on lean mass was lost when only including studies with RT in the analysis (n=7 comparisons; 0.23 kg; 95%CI= -0.17 to 0.63). The beneficial effect of WP on lean mass was more robust when only including studies with an ER component (n=6 comparisons; 0.90 kg; 95%CI= 0.31 to 1.49). There was no effect of WP on lean mass in studies without ER (n=9 comparisons; 0.22 kg; 95%CI= -0.12 to 0.57).
Conclusion: Overall, WP supplementation equates to ~1% greater lean mass in women over the course of these trials. Considering that WP supplementation did not influence fat mass, this 1% difference in lean mass does not support the public perception that WP makes women "bulky". While more research is needed to specifically assess the effects in varying states of energy sufficiency and exercise training, the overall findings support consumption of WP in women seeking to modestly improve body composition.