In a randomized clinical trial with 92 functionally impaired men ages 65 or older, supplemental protein for 6 months did not significantly increase lean muscle over placebo.https://www.ncbi.nlm.nih.gov/pubmed/29532075
I actually hadn't seen that one, thanks! Honestly, I think that study kind of shows what I meant. Very minor benefit estimate based on a large number of studies each with a tiny sample size, and massive heterogeneity across studies