| Peptide | Claimed mechanism | Best human evidence | Evidence grade | FDA status | Dose in studies |
|---|
| Growth hormone (the benchmark, not a research peptide) | The hormone every secretagogue below tries to raise | Liu 2008, Ann Intern Med: systematic review, 303 young, fit adults given GH. Lean body mass up 2.1 kg; strength and exercise capacity did not improve; more swelling and fatigue. | Human RCT, muscle outcome | Prescription drug for GH deficiency. The Norditropin label states it is not indicated for adults without GH deficiency. | Mean 36 mcg/kg a day for a mean of 20 days (Liu 2008) |
| Tesamorelin | GHRH analogue, raises GH and IGF-1 | Falutz 2007, NEJM: 412 adults with HIV, 26 weeks; visceral fat down 15.2% vs up 5.0% on placebo, IGF-1 up 81%. The FDA label reports lean body mass up 1.3 kg and 1.2 kg in its two trials; a 2026 meta-analysis of five RCTs found +1.42 kg. All in HIV lipodystrophy. | Human RCT, muscle outcome (HIV patients only) | Approved as Egrifta WR to reduce excess abdominal fat in adults with HIV and lipodystrophy; the label says it is not for weight loss. | 2 mg under the skin daily (Falutz 2007); label dose 1.28 mg daily for Egrifta WR |
| MK-677 (ibutamoren), an oral non-peptide secretagogue | Ghrelin mimetic, raises GH and IGF-1 | Nass 2008, Ann Intern Med: 65 healthy adults aged 60 to 81, 12 months; fat-free mass +1.1 kg vs -0.5 kg on placebo. No change in strength or function; fasting glucose up and insulin sensitivity down. | Human RCT, muscle outcome (older adults) | Not approved. In FDA category 2 for compounding, over a congestive heart failure signal in a hip fracture trial. | 25 mg by mouth once daily (Nass 2008) |
| Collagen peptides | Dietary protein | Zdzieblik 2015, Br J Nutr: 53 men with sarcopenia, average age 72, 12 weeks of resistance training; fat-free mass +4.2 kg vs +2.9 kg on placebo, quadriceps strength +16.5 vs +7.3 Nm. | Human RCT, muscle outcome (with training, older men) | A food protein, used in the trial as a supplement rather than a drug | 15 g a day (Zdzieblik 2015) |
| ACE-031 (ramatercept, a myostatin-blocking fusion protein rather than a short peptide) | Decoy activin receptor that soaks up myostatin | Attie 2013, Muscle Nerve: 48 healthy postmenopausal women, one injection; at 3 mg/kg, total lean mass +3.3% and thigh muscle volume +5.1% at day 29. A trial in boys with Duchenne muscular dystrophy was stopped over nosebleeds and dilated small blood vessels (Campbell 2017). | Human RCT, muscle outcome (single dose) | Not approved | One injection, 0.02 to 3 mg/kg (Attie 2013) |
| Sermorelin | Short GHRH analogue (GHRH 1-29) | Khorram 1997, JCEM: 19 adults aged 55 to 71 injected a closely related GHRH(1-29) analogue nightly for 16 weeks after a 4-week placebo run-in. GH and IGF-1 rose; lean body mass increased in the 9 men only. Single blind. | Small human study, muscle outcome | Once FDA approved for children with GH deficiency and commercially withdrawn in 2008; no current approval for body composition (2026 review). | 10 mcg/kg nightly (Khorram 1997) |
| CJC-1295 (with DAC) | Long-acting GHRH analogue | Teichman 2006, JCEM: two randomised, placebo-controlled dose-ranging trials in healthy adults aged 21 to 61. One injection raised GH 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days. No muscle outcome measured. The version without DAC is essentially unstudied in humans (2026 review). | Human data, no muscle outcome | Not approved. Listed by FDA among compounding nominations withdrawn from category 2, citing serious adverse events including increased heart rate. | Single and repeated injections; 30 or 60 mcg/kg best tolerated (Teichman 2006) |
| Ipamorelin | Selective ghrelin receptor agonist (GH secretagogue) | No human muscle trial. In Beck 2014, a phase 2 trial in 114 bowel surgery patients, it did not beat placebo for postoperative ileus. | Human data, no muscle outcome | Not approved. In FDA category 2 for outsourcing facilities; FDA cites a published report of serious adverse events including death with intravenous use. | 0.03 mg/kg intravenously twice daily for up to 7 days, in surgical patients (Beck 2014) |
| GHRP-2, GHRP-6, hexarelin | Ghrelin receptor agonists (GH releasing peptides) | Human studies are mostly short hormone-response and childhood GH deficiency work. A 2026 review finds no controlled efficacy data for body composition or performance. | Human data, no muscle outcome | Not approved. GHRP-2 and GHRP-6 are in FDA category 2 for outsourcing facilities. | Mostly single intravenous test doses of about 1 mcg/kg (2026 review) |
| BPC-157 | Claimed to speed tendon, ligament and muscle repair | No human trial with a muscle outcome; a PubMed search on 14 October 2026 returned no record indexed as a clinical trial. FDA says it has no, or only limited, safety information. | No human muscle data | Not approved. In FDA's table of nominations withdrawn from category 2; on the July 2026 compounding committee agenda for ulcerative colitis, not muscle. | No human dose data |
| TB-500 (thymosin beta-4 fragment) | Claimed to aid recovery and tissue repair | No human muscle trial. FDA says it has not identified any human exposure data for the fragment. | No human muscle data | Not approved. In FDA's withdrawn-nomination table; on the July 2026 committee agenda for wound healing. | No human dose data |
| IGF-1 LR3 | Long-acting IGF-1 analogue | No peer-reviewed human studies; the 2026 review puts it in its lowest evidence tier. | No human muscle data | Not approved | No human dose data |
| Follistatin-344 | Binds and blocks myostatin | No human trial of the injected peptide. The only human data is a gene therapy version injected into the thigh muscles of 6 patients with Becker muscular dystrophy; 4 walked further in 6 minutes (Mendell 2015). | No human muscle data (for the peptide) | Not approved | No human dose data for the peptide |