physical · Outcome
Total lean tissue. Cornerstone of healthy aging; sarcopenia starts around age 30 and accelerates after 60 without active loading.
How to measure: DEXA scan annually, BIA scale weekly trend, or tape-measure circumferences. Strength gains in compound lifts track muscle gain closely enough for most people.
Three levers, one stack. Each works through a different mechanism. They compound.
+0.9 kg lean
20-40 g per serving, hitting 1.6-2.2 g/kg total daily protein · Anytime, but post-training is convenient
Evidence
Effect size
Research
127 papers
range 0–3.3 · n=35 quantitative claims
“Whey protein supplementation significantly increased gait speed in older adults with sarcopenia compared to isocaloric placebo or routine consultation.”
Why: Most-studied muscle-building supplement, but the effect is conditional on total protein intake. If you already eat 1.6 g/kg from whole food, extra whey adds almost nothing. Use it to fill the gap, not as the goal.
+1 kg lean
10-20 hard sets per muscle per week · 2-4 sessions per week
Evidence
Effect size
Research
208 papers
range -0.6–7.4 · n=60 quantitative claims
Evidence pending
2-3 whole eggs in a meal · Any meal, breakfast tends to be easiest to anchor
Evidence
Effect size
Research
None
Everything we found, ranked by how strongly we recommend it. Tap any to see the studies.
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Every pick has two signals. They answer different questions and we never bundle them into one number.
Effect size
How big is the change on muscle mass, in the units that matter for this outcome.
Confidence
How sure are we the effect is real for muscle mass, given the studies we have.
For every pick, the “papers” number is how many studies we've cataloged that test this entity for muscle mass. “Favorable” means the study reported the direction you want.
The tier badge (S, A, B…) on the entity itself is its overall research confidence across all outcomes. It's the same letter wherever you see this entity on the site, not specific to muscle mass.
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“Combined resistance training and amino acid supplementation significantly improved gait speed compared to resistance training alone in older adults with sarcopenia.”
Why: Protein is the building material. Loading is the signal that tells the body to use it. Skip the loading and the protein gets oxidized. This is the only intervention in this list that is non-negotiable.
Why: Whole eggs beat egg whites for muscle protein synthesis in head-to-head trials, the yolk contributes lipid-soluble cofactors. The cholesterol concern is overstated for most people.