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 you can get prescribed (2026)
Which muscle peptides a U.S. clinician can prescribe and a licensed pharmacy can fill, what they cost, where each stands with the FDA and WADA, and where you can lawfully buy them.
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 benefits: does it work? What the trials show
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: what the evidence shows for each one
An evidence ranking, not a shopping list. 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 muscle data is testosterone, and it isn’t 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 peptide: benefits, side effects and what the evidence shows
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 peptide (elamipretide): benefits, evidence and approval status
An elegant mitochondrial mechanism meets a hard clinical record: a cardiolipin-binding peptide with 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.