Morton et al. 2018, Protein supplementation and resistance training gains: systematic review, meta-analysis and meta-regression

A systematic review, meta-analysis and meta-regression of 49 RCTs (n = 1,863; British Journal of Sports Medicine 52(6):376–384; DOI: 10.1136/bjsports-2017-097608) found that protein supplementation during resistance training significantly increased fat-free mass (+0.30 kg) and one-repetition-maximum strength (+2.49 kg). A segmental meta-regression identified a plateau: supplementing beyond a total protein intake of 1.62 g/kg/day yielded no additional gains in fat-free mass (95 % CI 1.03–2.20 g/kg/day). Age attenuated the response. Strong evidence.