Verified July 2026 · Cited to primary sources
The GH-axis peptides marketed for muscle and body recomposition, graded by human evidence and legal status. Most of the hype (CJC-1295/Ipamorelin) rests on a single pharmacokinetic study, which is not proof of muscle gain.
Strongest human evidence in this category
Sermorelin (Grade B) is the best-evidenced option with a legal compounding route. Tesamorelin (Grade A) is proven for visceral fat but approved only for HIV lipodystrophy. CJC-1295/Ipamorelin (Grade C) raises GH/IGF-1 in one study but has no trial showing it builds muscle, and it is not legally compoundable.
How we ranked these
We don't rank by popularity or by what we can sell you. Every peptide below is ordered by the same fixed rubric, and affiliate availability never moves a grade.
A historical FDA survey of compounded drugs found 31% failed standard potency testing. What is actually in the vial is a separate question from whether the compound works, and a rubric like this exists to keep the two apart. See the full A to F methodology →
A GHRH analog that stimulates the pituitary to release growth hormone, which reduces visceral (abdominal) fat.
Tesamorelin is an FDA-approved drug (Egrifta, 2010): Grade A, the strongest evidence tier here. But it is approved for HIV-associated visceral fat, not general weight loss; for that, approved GLP-1s are the evidence-backed route.
See the evidence →Stimulates natural pituitary growth-hormone release as the shortest active GHRH(1-29) fragment. The "gentler," physiologic GH-axis peptide.
Sermorelin is legally compoundable (503A) thanks to its prior FDA approval as Geref. Human evidence is Grade B: real historical trial data. It is the best-evidenced GH-axis peptide with a legal supervised route today.
See the evidence →CJC-1295 (a GHRH analog) drives sustained pituitary GH/IGF-1 release while Ipamorelin (a selective ghrelin/GHS-R agonist) adds a clean GH pulse. The stack aims to raise GH/IGF-1.
CJC-1295/Ipamorelin is not FDA-approved and is not legally compoundable (CJC-1295 withdrawn April 2026). Human evidence is Grade C: one PK study proves it raises GH/IGF-1, but no trial shows muscle or fat-loss benefit. Researching CJC-1295 on its own (often "with DAC")? See our standalone CJC-1295 page.
See the evidence →A modified GHRH analog that stimulates sustained pituitary GH and IGF-1 release; the "with DAC" (Drug Affinity Complex) version binds albumin to extend its half-life to days, versus the shorter-acting no-DAC form (Mod-GRF 1-29).
CJC-1295 (mono GHRH analog, usually "with DAC") is not FDA-approved and not legally compoundable; its nomination was withdrawn in April 2026. Human evidence is Grade C: one PK study proves it raises GH/IGF-1, but no trial shows muscle or fat-loss benefit. Most people search for the popular blend, so see our CJC-1295 / Ipamorelin page. We don't link gray-market sources.
See the evidence →Binds the ghrelin receptor (GHS-R1a) on pituitary somatotroph cells and triggers a pulse of stored growth hormone. Its selling point is selectivity: at GH-releasing doses it does not meaningfully raise ACTH, cortisol, prolactin, FSH, LH or TSH, which is what separates it from GHRP-6 and GHRP-2. It still needs your own GHRH axis to work, so it is not a substitute for GH itself.
The most selective GHRP on paper and the best-tolerated in a real human trial, but that trial failed and there is no human evidence it does the muscle or fat-loss job it is sold for. Interesting pharmacology, unproven benefit, not legal to compound.
See the evidence →Non-peptide agonist of the ghrelin receptor (GHS-R1a) that mimics ghrelin to drive sustained, roughly physiological increases in growth hormone and IGF-1. Because it is orally bioavailable and long-acting, one daily dose keeps GH/IGF-1 elevated, unlike the injectable peptide GHRPs. That same sustained GH/IGF-1 elevation is what drives its main downside: reduced insulin sensitivity and higher fasting glucose.
The most-studied and only orally-active option in this group, with genuine 2-year human RCT data behind it, which is why it grades C and not D. But the same trial that proves it works also shows the catch: modest lean-mass gain, no functional benefit, and worse insulin sensitivity. Not FDA-approved, research-only, and a poor idea for anyone with blood-sugar concerns.
See the evidence →A modified, long-acting form of IGF-1 that activates the IGF-1 receptor to drive the PI3K/Akt/mTOR protein-synthesis and satellite-cell pathways. That's the theoretical basis for its muscle-growth marketing.
IGF-1 LR3 is not FDA-approved and not legally compoundable; it's research-only. Human evidence is Grade D: there is no published human efficacy trial for the analogue itself, so the muscle-growth claims rest on mechanism, not proof. It is also WADA-prohibited (S2). We don't link gray-market sources.
See the evidence →Agonist at the ghrelin receptor (GHS-R1a) that triggers a pulse of pituitary growth hormone. Unlike ipamorelin it is non-selective: it also raises ACTH, cortisol and prolactin, stimulates appetite hard, and has gastric-motility effects. Human work shows it needs your own hypothalamic GHRH to hit maximal GH release, so its ceiling depends on an intact GHRH axis.
The granddaddy of GH peptides and a reliable appetite-and-GH trigger in the lab, but it is non-selective (cortisol and prolactin come along), the human data is decades-old pharmacology with no efficacy outcome, and it is not legal to compound. Newer selective secretagogues make it hard to justify even in theory.
See the evidence →Ghrelin-receptor (GHS-R1a) agonist that drives some of the highest GH pulse amplitudes per unit dose in its class. It works partly independent of your own GHRH: in patients with a non-functional GHRH receptor it still produced a 4.5-fold GH rise, showing a direct action on pituitary somatotrophs. It also stimulates appetite and modestly raises ACTH, cortisol and prolactin.
The strongest GH-pulse trigger of the old GHRPs and a genuine diagnostic drug in Japan, which is more legitimacy than most peptides here can claim. But a single approved diagnostic test is not evidence it builds muscle, no such human trial exists, and in the US it is research-only. Grades D for the use case people search for.
See the evidence →Agonist at the ghrelin receptor (GHS-R1a) that triggers pituitary GH release. Uniquely, it also acts on the cardiac scavenger receptor CD36, and human studies show an acute, short-lasting positive inotropic effect (better left-ventricular ejection fraction) that is independent of GH. The catch for GH use is desensitization: repeated dosing blunts the GH response (tachyphylaxis), so the hormonal effect fades.
The most scientifically interesting GHRP thanks to a real, human, GH-independent cardiac effect, but 'interesting mechanism' is not 'proven benefit.' No trial shows it builds muscle, its GH effect fades with repeat dosing, and it is research-only. Grades D for the use case people actually search.
See the evidence →Follistatin binds and neutralizes myostatin (GDF-8) and activins, removing a brake on skeletal-muscle growth. Blocking myostatin drives muscle-fiber hypertrophy, which is why it is attractive for muscle building. The catch is that follistatin is a large, short-lived glycoprotein, so a simple injected peptide does not durably produce the effect, which is why the credible human work used gene therapy to make muscle express it continuously.
A compelling target with a misleading reputation. The muscle-growth story rests almost entirely on animal work plus a tiny AAV gene-therapy trial that is not the same product as the injectable peptide being sold. For follistatin as a peptide, the human efficacy evidence is basically Grade D, safety is uncharacterized, systemic myostatin blockade carries real theoretical risks, and it is banned in sport. Interesting biology, not a justified purchase.
See the evidence →MGF is the C-terminal E-domain of the IGF-1Ec splice variant, produced locally in skeletal muscle in response to mechanical overload or damage. The proposed mechanism is autocrine/paracrine activation of muscle satellite cells (the resident stem cells that repair and enlarge fibers), acting through a receptor distinct from the classic IGF-1 receptor. In practice the receptor and downstream signaling remain poorly characterized, and whether the synthetic peptide reproduces the biology of the natural splice event is unresolved.
Skip it. The idea (a local muscle-repair growth factor you can inject) is attractive, but the honest read of the literature is preclinical at best and negative in the one rigorous cell study. There is no human evidence it builds muscle, it is banned in sport, and injecting an unverified growth factor is not a low-risk bet.
See the evidence →PEG-MGF is the MGF (IGF-1Ec E-domain) peptide conjugated to polyethylene glycol. Native MGF has a very short systemic half-life (minutes); PEGylation slows clearance and is meant to give the peptide time to reach tissue and act on satellite cells. The proposed downstream biology is identical to MGF: satellite cell activation, proliferation, and fusion to support fiber repair and hypertrophy. Whether extending the half-life of a peptide that may not be active in the first place produces a real anabolic effect is exactly the open question.
Skip it. PEG-MGF is a chemically reasonable attempt to fix MGF's short half-life, but fixing the delivery of a compound with no proven human effect does not create a proven human effect. Animal data only, banned in sport, unverified injectable. Not worth the risk.
See the evidence →| Peptide | Evidence | Legal & safety | Typical cost | Verdict | |
|---|---|---|---|---|---|
| Tesamorelin An FDA-approved peptide drug, not a research chemical. Proven to cut visceral fat, but approved for a narrow HIV indication. | Grade A | See evidenceSee the evidence for Tesamorelin | |||
| Sermorelin The "gentler," formerly-FDA-approved GH-axis peptide. It's the best-evidenced option you can still legally get through a compounding pharmacy. | Grade B | See evidenceSee the evidence for Sermorelin | |||
| CJC-1295 / Ipamorelin The classic GH-boosting stack. One human PK study shows it raises GH/IGF-1, but no trial shows it builds muscle or burns fat. | Grade C | See evidenceSee the evidence for CJC-1295 / Ipamorelin | |||
| CJC-1295 A GHRH analog, usually the long-acting "with DAC" version, that one human study shows raises GH/IGF-1. No trial shows it builds muscle or burns fat. | Grade C | See evidenceSee the evidence for CJC-1295 | |||
| Ipamorelin The cleanest of the GH-releasing peptides on paper: it bumps GH without the cortisol and prolactin spike the older GHRPs cause. But the honest headline is that the one real human trial was for gut motility, not muscle, and it flat-out failed. Zero human data proving it builds muscle or burns fat. | Grade C | See evidenceSee the evidence for Ipamorelin | |||
| MK-677 (Ibutamoren) The odd one out: MK-677 is not a peptide, it is an orally-active small-molecule ghrelin mimetic, which is why people take it as a daily capsule instead of an injection. It has the best human evidence in this group by far, including a 2-year randomized trial, but that trial is also the cautionary tale: it raised lean mass a little while measurably worsening insulin sensitivity and blood sugar. | Grade C | See evidenceSee the evidence for MK-677 (Ibutamoren) | |||
| IGF-1 LR3 A long-acting IGF-1 analogue marketed for muscle growth on the strength of its mechanism alone. There is no published human efficacy trial for it, and it's banned in sport. | Grade D | See evidenceSee the evidence for IGF-1 LR3 | |||
| GHRP-6 The original GH-releasing peptide from the 1980s. It works as a GH pulse trigger and it makes you ravenously hungry, but it is non-selective, so it drags cortisol and prolactin up with it. Human data is all old pharmacology studies, none of it shows it builds muscle. | Grade D | See evidenceSee the evidence for GHRP-6 | |||
| GHRP-2 The most potent GH-pulse trigger of the classic GHRPs per dose, and it is actually an approved diagnostic agent for GH deficiency in Japan. But like its cousins it also spikes appetite and modestly raises cortisol and prolactin, and there is no human trial showing it builds muscle. | Grade D | See evidenceSee the evidence for GHRP-2 | |||
| Hexarelin The GHRP with the most interesting side story: beyond releasing GH it has a direct, GH-independent positive effect on heart contractility in humans via a cardiac receptor. That cardiac finding is real and human. What is missing is any trial showing it does the muscle-building it is sold for, plus it loses its GH punch fast with repeat dosing. | Grade D | See evidenceSee the evidence for Hexarelin | |||
| Follistatin (FST-344 / FS344) A natural myostatin blocker that in theory should unlock muscle growth. The reality: the injectable peptide is essentially preclinical, and the only human evidence is from AAV gene therapy, a completely different technology, in a handful of muscular-dystrophy patients. | Grade D | See evidenceSee the evidence for Follistatin (FST-344 / FS344) | |||
| MGF (Mechano Growth Factor) A short splice variant of IGF-1 that muscle makes locally after mechanical stress. The theory is great, the human data barely exists, and the one well-run cell study said it did nothing. | Grade D | See evidenceSee the evidence for MGF (Mechano Growth Factor) | |||
| PEG-MGF (Pegylated Mechano Growth Factor) MGF with a polyethylene glycol tail bolted on to make it last longer in the blood. Longer half-life, same problem: the evidence is animal-only and no human trial has shown it does anything. | Grade D | See evidenceSee the evidence for PEG-MGF (Pegylated Mechano Growth Factor) |
Reading this table: Evidence is the A to F human-proof grade; Legal status and Safety are separate factual badges; Verdict is our honest one-line take. Affiliate availability never changes a grade. Full methodology.
FAQ
The best-evidenced option with a legal route is sermorelin (Grade B), a formerly FDA-approved GHRH analog that is still legally compoundable. Tesamorelin (Grade A) is proven to cut visceral fat but is approved only for HIV lipodystrophy. CJC-1295/Ipamorelin (Grade C) raises GH and IGF-1 in one study, but no trial shows it actually builds muscle.
There is no human trial showing CJC-1295/Ipamorelin builds muscle or burns fat. The only human data is a pharmacokinetic study confirming it raises GH and IGF-1, which is why we grade it C. It is also not legally compoundable.
Sermorelin is legally compoundable through a 503A pharmacy because of its prior FDA approval. CJC-1295/Ipamorelin is effectively research-only after CJC-1295's compounding nomination was withdrawn in April 2026. All of these are on the WADA Prohibited List for tested athletes.
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