Protein Intakes Greater Than vs. at the RDA Differentially Affect Lean Body Mass Change to Purposeful Catabolic and Anabolic Stressors: A Systematic Review and Meta-analysis (P08-075-19)

Abstract

ObjectivesUnder stressful conditions such as energy restriction (ER) and resistance training (RT), recommended dietary allowance (RDA) for protein of 0.8 g/kg/d may no longer be an appropriate recommendation. Higher protein intakes are proposed to help promote, preserve, or attenuate the loss of lean mass. No known meta-analysis has been published previously that compares protein intakes greater than the RDA vs. the RDA as a control group. Therefore, we conducted a systematic review and meta-analysis to assess the effects of protein intake greater than versus at the RDA on changes in whole-body lean mass. MethodsThree researchers independently screened 1531 articles published through August 2018 using PubMed, Scopus, CINAHL, and Cochrane databases, with additional articles identified through previously published review articles. Randomized-controlled, parallel studies at least 6 weeks long with apparently healthy adults (> = 19 years old) were eligible for data extraction. (PROSPERO, CRD 42018106532). ResultsData from 19 studies resulting in 23 comparisons of lean mass changes were included in the final analysis. This abstract presents sub-analyses for comparisons with catabolic and anabolic stimuli, specifically ER and/or RT, respectively. Among all comparisons, protein intakes greater than the RDA attenuated lean mass loss after ER [0.41 kg (0.15, 0.67); WMD (95% CI), n = 15 comparisons], but did not influence lean mass change without ER [0.23 kg (−0.44, 0.89), n = 8]. Protein intakes greater than the RDA increased lean mass after RT [0.77 kg (0.23, 1.31), n = 3], but not influence change in lean mass without RT [0.29 kg (−0.04, 0.62, n = 20]. ConclusionsProtein intakes greater than the RDA positively influence changes in lean mass when adults are purposefully stressed by the catabolic stimulus of dietary energy restriction and/or the anabolic stimulus of resistance training. The RDA for protein is adequate for adults during non-stressed states. Funding SourcesPurdue University Lynn Fellowship. No external funding was provided for this review.