Best peptides for muscle growth.
A category with enormous marketing energy behind it and almost no completed human outcome evidence to show for it.
Ranked by published evidence · reviewed June 1, 2026
Muscle growth is where the distance between what is claimed and what has been demonstrated is at its widest. Almost every compound in this category is a growth hormone secretagogue, and almost all of them do reliably raise growth hormone. That part is real and measurable. What is missing is any substantial body of evidence that raising GH in an otherwise healthy adult produces meaningful muscle growth.
This is a specific and important distinction. Growth hormone is not primarily an anabolic hormone in the way testosterone is. Much of the visible effect of high-dose GH in bodybuilding contexts is attributable to fluid retention and to changes in fat mass rather than contractile tissue. The trials that would separate those effects in healthy trained adults using secretagogues have largely not been run.
The most interesting compound in this category from an evidence standpoint is also a cautionary tale. ACE-031 is a myostatin trap, targeting the pathway that actively restrains muscle growth, and unlike almost everything else here it reached randomized human trials. Those trials were halted in 2011 after participants developed nosebleeds and dilated skin vessels, off-target effects of trapping ligands beyond myostatin. It is the one compound in this list with real human data, and that data is why it was discontinued.
Another instructive case is MGF, which is marketed as a mechanically-triggered muscle growth factor. The original work suggested the peptide fragment activated muscle satellite cells. An independent laboratory subsequently tested the isolated peptide and found no effect on myoblast or human muscle stem cell proliferation at any concentration tested, while the parent hormone IGF-1 worked as expected. A failure to reproduce is real evidence, and it points the other way.
No compound in this category has demonstrated meaningful muscle growth in healthy adults in controlled human trials. The one that got furthest into human testing was stopped for safety. Treat confident muscle-growth claims here as marketing.
Ranked by evidence.
Ordered by PepCue's evidence tier, not by claimed effect size. A compound with a larger reported result but less human data ranks below one that has actually been tested.
- 01Human Growth HormoneS tier · 90/100FDA-approvedHGH · somatropin
Human growth hormone (hGH, also called somatotropin) is a 191-amino-acid, single-chain polypeptide hormone secreted by somatotroph cells of the anterior pituitary gland.
Full profile and sources → - 02SermorelinC tier · 58/100Research / preclinical
Sermorelin is a synthetic 29-amino-acid peptide corresponding to the N-terminal 1-29 fragment of human growth hormone-releasing hormone (GHRH), the hypothalamic hormone that signals the pituitary to release growth hormone (GH).
Full profile and sources → - 03ACE-031D tier · 49/100In human trialsramatercept · ActRIIB-Fc
ACE-031 (ramatercept) is not a peptide but a recombinant fusion protein that joins the extracellular domain of the human activin receptor type IIB (ActRIIB) to the Fc region of IgG1.
Full profile and sources → - 04GHRP-2D tier · 38/100Research / preclinical
GHRP-2 (growth hormone-releasing peptide-2; international nonproprietary name pralmorelin; development codes KP-102/GPA-748) is a synthetic hexapeptide with the sequence D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2.
Full profile and sources → - 05GHRP-6D tier · 38/100Research / preclinical
GHRP-6 (growth hormone-releasing peptide-6) is a synthetic hexapeptide with the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2.
Full profile and sources → - 06GHRP-1D tier · 38/100Research / preclinicalgrowth hormone-releasing peptide-1
GHRP-1 is a synthetic heptapeptide, one of the earliest growth hormone-releasing peptides (GHRPs) developed by Cyril Bowers' group in the 1980s and 1990s alongside GHRP-2 and GHRP-6.
Full profile and sources → - 07HexarelinD tier · 38/100Research / preclinical
Hexarelin (examorelin) is a synthetic hexapeptide growth hormone secretagogue (GHS), structurally derived from the GHRP-6 family of growth hormone-releasing peptides.
Full profile and sources → - 08IGF-1 LR3F tier · 33/100Research / preclinical
IGF-1 LR3 (Long R3 IGF-1) is a synthetic, recombinant analog of human insulin-like growth factor-1.
Full profile and sources → - 09IpamorelinF tier · 33/100Research / preclinical
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) belonging to the growth hormone-releasing peptide (GHRP) class, sometimes described as a "third-generation" GHRP.
Full profile and sources → - 10CJC-1295F tier · 33/100Research / preclinical
CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), based on the first 29 amino acids of human GHRH (GRF 1-29) with several amino-acid substitutions that resist enzymatic degradation.
Full profile and sources → - 11CJC-1295 DACF tier · 29/100Research / preclinical
CJC-1295 with DAC (also written DAC:GRF, CJC-1295 DAC) is a synthetic, long-acting analog of growth hormone-releasing hormone (GHRH).
Full profile and sources → - 12Mod-GRF (1-29)F tier · 29/100Research / preclinicalCJC-1295 no-DAC
Mod GRF 1-29 (commonly sold as "CJC-1295 without DAC") is a synthetic 29-amino-acid analog of growth hormone-releasing hormone (GHRH).
Full profile and sources → - 13Follistatin-344F tier · 28/100Research / preclinical
Follistatin-344 (FS-344) is an alternatively spliced isoform of human follistatin, a naturally occurring secreted glycoprotein that acts as a high-affinity antagonist of several TGF-beta superfamily ligands.
Full profile and sources → - 14MGFF tier · 15/100Research / preclinicalmechano growth factor · IGF-1Ec
MGF is a splice variant of insulin-like growth factor 1 (IGF-1), designated IGF-1Ec in humans and IGF-1Eb in rodents, produced locally in skeletal muscle in response to mechanical loading or damage.
Full profile and sources → - 15PEG-MGFF tier · 12/100Research / preclinical
PEG-MGF is a PEGylated synthetic peptide based on the unique C-terminal E-domain of mechano growth factor (MGF), an alternatively spliced isoform of insulin-like growth factor-1 known as IGF-1Ec (the rodent equivalent is IGF-1Eb).
Full profile and sources →
Commonly tried, and why it is not on this list.
Testosterone and anabolic steroids
These are not peptides and sit outside this site's scope, but they are the compounds with actual muscle-growth evidence, which is context worth having.
FAQ.
Do GH secretagogues build muscle?
They raise growth hormone, which is measurable. Whether that produces meaningful muscle growth in healthy adults has not been established in controlled trials, and growth hormone's effects on lean mass include substantial fluid retention.
What about IGF-1 LR3?
IGF-1 is genuinely anabolic in biology, and the LR3 analog has an extended half-life. There are no controlled human trials of it for muscle growth, and unregulated growth-factor signalling carries theoretical risks around promoting proliferation of existing abnormal tissue.
Why is ACE-031 not recommended if it worked?
Its trials showed lean mass changes but were halted in 2011 for dose-related vascular side effects including nosebleeds and telangiectasias. Development was discontinued. It is a demonstration that the mechanism does something, and that what it does is not safely controllable.
Cite this page
PepCue. “Best peptides for muscle growth: what the evidence actually shows.” PepCue, reviewed June 1, 2026. https://www.pepcue.app/best-peptides-for/muscle-growth.