How strong is the evidence for Protein?

A foundational meta-analysis and meta-regression established that protein supplementation meaningfully augments resistance-training-induced gains in muscle mass and strength in healthy adults, and this has been extensively replicated in older adults with sarcopenia specifically, including network meta-analyses comparing different protein types and dosing strategies. That evidence is currently rated strong (82/100), built on 10 published studies, including 8 meta-analyses -- enough for real confidence in the effect.