Longevity & Aging · Metabolic & Cardiometabolic
dietary protein for muscle does not increase muscle hypertrophy
In plain terms: Is there a point where extra protein stops building more muscle, around 1.6 g/kg?
Part of: • Cardiorespiratory Fitness & Strength
Supported as the best current estimate — the pooled breakpoint sits near 1.6 g/kg with wide uncertainty and no demonstrated benefit at 2.2 g/kg, though Topol is right that the underlying meta-regression was not statistically significant, so the exact number is soft.
📅 Last reviewed: 2026-07-14 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
About 1.6 grams per kilogram is the best current estimate of where added protein stops adding muscle, and trials above roughly 2 grams generally show no further benefit, including a year-long trial in trained women. The uncertainty around that breakpoint is wide, and in older adults the effect of extra protein is modest and inconsistent rather than clearly absent.
The evidence (14)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Vieira AF, Santos JS, Costa RR, Cadore EL, Macedo RCO 2022 · Sports Med | meta-analysis | mixed | moderate | Umbrella over syntheses: 'The pooled effect estimates were computed from the standardized mean difference and the 95% confidence interval achieved by each meta-analysis'; 'Five reviews were included'. Found supplementation + RT increased lean mass but not strength vs RT alone; no dose threshold (1.6 g/kg) tested. Review — zero weight. |
| Unterberger S, Aschauer R, Zöhrer PA, Draxler A, Franzke B, Strasser EM, Wagner KH, Wessner B 2022 · Clin Nutr | RCT | mixed | moderate | RCT doubling protein to ~2 g/kg/day before resistance training in older adults showed it did not clearly outperform normal intake for most outcomes, supporting a plateau but in an older population. |
| Eglseer D, Reiter L, Schoufour JD, Vágnerová T, Memelink RG, Verreijen AM, Borenich A, Bauer S, Weijs PJ 2026 · BMC Nutr | observational | tested-null | low | Secondary analysis of 3 RCTs in older adults during weight loss found higher protein preserved lean tissue but no benefit for strength/function, a context-dependent caveat to a hard universal plateau. |
| Antonio J, Ellerbroek A, Carson C 2018 · J Funct Morphol Kinesiol | observational | tested-null | low | One-year RCT in trained women consuming >2.2 g/kg/day found no additional favorable body-composition change vs habitual intake, consistent with no extra benefit far above ~1.6 g/kg. |
| Kirwan RP, Mazidi M, Rodríguez García C, Lane KE, Jafari A, Butler T, Perez de Heredia F, Davies IG 2022 · Am J Clin Nutr | meta-analysis | mixed | moderate | In older adults protein augments RET-induced appendicular lean mass/grip modestly and inconsistently — no evidence of dose-dependent benefit into the 2+ g/kg range, consistent with a plateau. |
| Ely IA, Paul M, Wall JJS, Cox J, Larsen MS, Scaife PJ, Lund JN, Breen L, Wilkinson DJ, Smith K, Phillips BE, Atherton PJ 2025 · Nutrients | RCT | tested-null | moderate | Acute RCT in young men showed leucine-rich lower-dose protein stimulated muscle protein synthesis comparably to larger doses, supporting a saturable/plateau MPS response. |
| Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, Aragon AA, Devries MC, Banfield L, Krieger JW, Phillips SM 2018 · Br J Sports Med | meta-analysis | supports | moderate | 49-study meta-regression: fat-free-mass gains plateaued at about 1.62 g/kg/day; protein-supplement breakpoint effect had p=0.079 (not significant), confirming Topol's caveat that even the 1.6 figure is statistically fragile. |
| Ioannidou P, Dóró Z, Schalla J, Wätjen W, Diel P, Isenmann E 2024 · J Nutr Health Aging | RCT | supports | low | 12-week RCT in postmenopausal women found the high-protein arm did not consistently exceed adequate-protein controls, aligning with diminishing returns. |
| Huang LP, Condello G, Kuo CH 2021 · Nutrients | meta-analysis | mixed | moderate | Meta-analysis in older adults found modest milk-protein augmentation of resistance-training lean-mass gains, with several whey studies showing no added effect, indicating benefit saturates. |
| Kanaan MF, Nait-Yahia S, Doucet É 2025 · Eur J Clin Nutr | RCT | mixed | moderate | Study in recreational athletes under energy restriction examined whether protein above 1.2-1.7 g/kg better preserves fat-free mass, reflecting that in energy deficit higher intakes may add benefit. |
| Biersteker EJM, Benali M, den Helder JV, Twisk J, Tieland M, Weijs PJM, Schoufour JD 2026 · The journal of nutrition, health & aging | RCT | mixed | moderate | Secondary analysis of a 12-week RCT (n=295 frail older adults) targeting 1.2-1.5 g/kg/day protein via whey supplementation found no overall added benefit on leg-press 1RM, lean mass, or physical performance vs resistance training alone. Exp |
| Tagawa R, Watanabe D, Ito K, Otsuyama T, Nakayama K, Sanbongi C, Miyachi M 2022 · Sports Med Open | meta-analysis | supports | high | Dose-response meta-analysis found total protein increased muscle strength with resistance training but with diminishing returns as intake rose, consistent with a plateau at moderate-to-higher intakes. |
| Xie C, Yan R, Tao R 2026 · BMC musculoskeletal disorders | meta-analysis | tested-null | low | Meta-analysis of 9 RCTs (n=496 sarcopenic older adults) found amino acid supplementation + resistance training improved handgrip strength and physical performance vs resistance training alone (low-to-very-low certainty), but no significant |
| Davis BE, Young I, Giglotti JC, Yao J, Tou JC 2026 · J Diet Suppl | meta-analysis | mixed | moderate | Meta-analysis (12 RCTs) found whey/soy supplementation did not significantly increase lean body mass in young trained adults, consistent with limited marginal benefit above adequate intake. |
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