Longevity & Aging · Metabolic & Cardiometabolic
testosterone therapy increases muscle mass and strength
In plain terms: Does testosterone therapy build muscle?
Part of: 💊 Testosterone therapy (TRT)
Yes — in men who genuinely have low testosterone, it reliably increases muscle mass and strength, and the effect is dose-dependent (one of TRT's most consistent benefits). Two caveats: injections work better than gels, and more muscle doesn't automatically mean better everyday physical function, especially in older men.
📅 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
In men with low testosterone, testosterone therapy reliably increases lean (fat-free) muscle mass and strength — this is one of TRT's best-established effects. Multiple meta-analyses and classic dose-response trials show clear, dose-dependent gains (often 1.5-3 kg of lean mass, more at higher doses).
The evidence (18)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Krause Neto W et al. 2015 · Aging Male | meta-analysis | supports | moderate | Meta 11 RCTs (men >60y): lean mass +3.59 kg pooled (high heterogeneity I2=98%). |
| Isidori AM et al. 2005 · Clin Endocrinol (Oxf) | meta-analysis | supports | high | Meta 29 RCTs (n=1083): fat-free mass +1.6 kg (+2.7%); strength effect modest/heterogeneous. |
| Hubska J et al 2026 · study_type: observational | n-of-1 | supports | low | Case report, one 32-year-old woman with CAH and androgen suppression: low-dose IM testosterone resolved severe muscle pain and improved strength within 3 months, sustained over 10-year follow-up. |
| Woodhouse LJ et al. 2003 · J Clin Endocrinol Metab | RCT | supports | moderate | Dose-response RCT: T dose predicted FFM gain; muscle volume rose dose-dependently. |
| Kolla B et al 2025 · study_type: observational | observational | supports | moderate | Prospective study, 22 transmen given testosterone GAHT over 12 months: muscle mass +7.2% and muscle strength increased at nearly all sites (P<0.001). |
| Snyder PJ et al. 2016 · N Engl J Med | RCT | mixed | high | Testosterone Trials (n=790): increased walking distance in pooled analysis but no clear physical-function benefit; strength not a primary outcome. |
| Bhasin S et al. 2001 · Am J Physiol Endocrinol Metab | RCT | supports | high | Dose-response RCT: fat-free mass increased dose-dependently up to +7.9 kg at highest dose; strength tracked dose. |
| Traish AM 2016 · Curr Opin Endocrinol Diabetes Obes | mechanism | supports | low | Review: T therapy consistently increases lean body mass and reduces fat mass across trials. |
| Ceolin C et al 2025 · study_type: observational | observational | supports | moderate | Prospective 1-year observational study, 107 trans/gender-diverse adults assigned female at birth on testosterone GAHT: handgrip strength rose +4.35 kg (25-29y, p=.001) and +2.14 kg (20-24y, p=.025), with smaller/non-significant gains in old |
| Parahiba SM et al. 2020 · Exp Gerontol | meta-analysis | supports | moderate | Meta 11 RCTs: lean body mass +2.54 kg; handgrip +1.58 kgf; leg strength increased. |
| Srinivas-Shankar U et al. 2010 · J Clin Endocrinol Metab | RCT | supports | moderate | RCT (frail elderly, n=274): lean mass up, knee-extension strength up vs placebo at 6 months. |
| Guo C et al. 2016 · Andrologia | meta-analysis | supports | moderate | Meta 16 RCTs: lean body mass +1.22 kg (95% CI 0.33-2.11). |
| Junjie W et al] # corrected 2026-08-17 from PubMed; was [Zhang J et al. 2019 · Aging Male | meta-analysis | supports | low | Meta 7 RCTs: increased lean mass and sex hormones; overall clinical benefit called limited. |
| López Hilario PP et al 2026 · study_type: meta-analysis | meta-analysis | supports | high | Umbrella review of 11 SRs/121 RCTs (20,846 men, 8447 on TRT, age >=60): lean body mass gain 1.6-3.59 kg across 5 moderate-high-quality SRs; strength gains smaller (leg press +91.2 N, 95% CI 0.23-182.22; leg extension +144.1 N, 95% CI 44.21- |
| Skinner JW et al. 2018 · J Cachexia Sarcopenia Muscle | meta-analysis | supports | high | Meta 31 RCTs: TRT increased fat-free mass (ES 1.20) and total-body strength (ES 0.90); IM route 3-5x more effective than transdermal. |
| Arora V et al 2026 · study_type: RCT | RCT | supports | moderate | RCT, 127 cirrhotic sarcopenic men: testosterone+nutrition+exercise vs nutrition+exercise alone; >=10% ASMI increase in 64.1% vs 25.3% (p<0.001), grip strength improved in 92% vs 67.3% (p=0.002). |
| Storer TW et al. 2008 · J Clin Endocrinol Metab | RCT | supports | moderate | Dose-response RCT (60-75y): dose-dependent gains in muscle mass and max leg-press strength; no change in physical function. |
| Mangolim AS et al. 2022 · Andrology | meta-analysis | supports | moderate | Meta 16 RCTs (obese men): ~2 kg lean body mass gain (moderate-certainty). |
Disagree, or know a study we missed?
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.