Muscle loss & sarcopenia
Losing muscle is a real concern both on rapid GLP-1 weight loss and with aging (sarcopenia). The durable, evidence-backed answer is boring — resistance training and adequate protein do most of the work — but several growth-hormone-axis and mitochondrial compounds are marketed for muscle. Here is the honest evidence on each.
Muscle loss on GLP-1 medications
Some of the weight lost on GLP-1s is lean mass — how much, and what actually protects it.
GLP-1 medications and muscle: what the body-composition data actually show
Some of the weight lost is lean mass — but the substudies show fat falls faster, the ratio improves, and resistance training plus protein is what protects muscle.
Best Peptides for Muscle Growth: An Evidence-Ranked Reality Check
We rank the peptides marketed for bodybuilding by the human data that actually exists — and none is approved or proven to build muscle.
Growth-hormone-axis peptides marketed for muscle
The GH secretagogues and analogs — real pharmacology, thin outcome data for body composition.
Ipamorelin & CJC-1295: the honest evidence on GH secretagogue peptides
They reliably raise growth hormone — that part is real. The muscle, fat-loss and anti-aging claims are not supported by human outcome data. A straight read.
Tesamorelin (Egrifta): what it's actually FDA-approved for, and the evidence
A real, approved GHRH analog — for HIV-associated lipodystrophy specifically. What the pivotal trials showed, and why the longevity use is an extrapolation.
IGF-1 LR3: a real anabolic hormone, engineered to last — and untested in people
IGF-1 is a genuine anabolic hormone and “Long R3” is engineered to dodge its binding proteins so it lasts far longer. But there are zero human muscle-building trials — and the risks (hypoglycemia, the growth-factor/cancer concern, a WADA ban) follow straight from the biology.
MK-677 (ibutamoren): raises the hormones, not (yet) the outcomes
An oral ghrelin mimetic that reliably lifts GH, IGF-1 and lean mass in human trials — but the same trials found no gain in strength, function or cognition, plus real metabolic and cardiac safety signals.
HGH Fragment 176-191: the GH “fat-loss fragment,” read against the trial that failed
It’s the C-terminal tail of growth hormone, sold as the part that burns fat. The honest anchor: its developed cousin AOD-9604 reached human obesity trials and failed to beat placebo — and the raw fragment sold today has no human trials at all.
Sermorelin: a real GHRH drug, read against the anti-aging pitch
An approved growth-hormone-releasing analog with a pediatric track record — and a longevity case built more on biomarkers than outcomes.
Mitochondrial & muscle-quality support
Compounds studied for muscle function, endurance, and the mitochondria that power it.
Peptides for muscle growth: an evidence ranking of what actually works
No peptide marketed for muscle growth has randomized human proof of bigger or stronger muscle. GH secretagogues move a biomarker; BPC-157 and TB-500 are animal-only; IGF-1 LR3 and follistatin are untested and WADA-banned. The molecule with real data is testosterone — not a peptide.
Urolithin A (Mitopure): real trials, modest results
A mitophagy-inducing postbiotic with unusually strong RCT evidence for a supplement — that reproducibly improves muscle endurance and biomarkers while repeatedly missing its primary strength endpoints.
MOTS-c: real mitochondrial biology, absent human evidence
A genuine mitochondrial-derived peptide with interesting rodent data on metabolism and exercise — but no human outcome trials. Promising biology, not a proven therapeutic.
SS-31 (elamipretide): an elegant mitochondrial mechanism meets a hard clinical record
A cardiolipin-binding peptide with a beautiful mechanism and a mostly disappointing trial history — including a failed myopathy trial and a narrow, confirmation-pending Barth syndrome approval. A straight read.
Taurine and aging: what the Singh 2023 Science work and the human data actually show
A robust mouse lifespan result — but 2025 human data found taurine doesn't reliably decline with age, and the only human trials are small cardiometabolic ones.
Compare peptide therapy providers
Where to get the growth-hormone-axis peptides — with honest framing on the thin body-composition evidence.