Best Peptides for Muscle Growth, Ranked by Evidence (2026)

"Best" on this page means one thing: best-evidenced for muscle growth in humans, scored on the rubric published on our editorial standards page. It is not a buying guide, it is not a stack, and it does not tell anyone how to use anything. It is a ledger: eleven rows, one scale, every number linked to the study or regulator that produced it, with the compounds sold as muscle-building peptides on the same scale as the supplements they are sold against. Scored that way, the usual listicle order inverts.

This page reports what studies show; it is not medical advice. Questions about a prescription product such as tesamorelin, or about using any supplement alongside a medical condition or medication, belong with a clinician.

The short answer

Creatine and protein have hundreds of randomized trials with strength and muscle-size endpoints. Collagen peptides have three. Tesamorelin and MK-677 have human body-composition data, but the "lean mass" they added came with no measured strength or function gain. Sermorelin's only placebo-controlled body-composition trial is 19 older adults, a modified analogue, and no strength test. CJC-1295, ipamorelin, the GHRPs, IGF-1 LR3, BPC-157 and TB-500 have no published human trial with a muscle-growth endpoint of any kind. And the "stack" that most competing pages recommend has never been tested in a single human study.

How this ledger scores

Criteria: MuscleLedger's published rubric. Reviewed 2026-09-05. FDA compounding status as shown on the FDA page dated April 22, 2026. WADA status from the Prohibited List valid January 1, 2026.

Our editorial standards weigh human trials over animal models, trained subjects over untrained, independent replication over single labs, and performance endpoints (strength, muscle cross-sectional area, work capacity) over biomarkers (hormone levels, fat-free mass on a scan). Two clarifications from the rubric as applied here:

• A row scores 1 when no human trial reports a muscle-relevant outcome (body composition, strength or muscle size); that floor is the most important fact about the compound. A 1 is not a negative result. It means nobody has measured it.
• Funding travels with the number. Where the seller paid for or supplied a trial, the row says so, and the score leans on replication rather than on any single result.

PubMed counts are records tagged Clinical Trial or Randomized Controlled Trial for the phrase shown, run on September 5, 2026; each count in the table links to its exact search, for example CJC-1295. A record count is a count of trials of any kind, not of muscle trials; the "human muscle-growth data" column answers the actual question.

The ledger: best peptides for muscle growth, ranked

Row notes

Creatine monohydrate

The International Society of Sports Nutrition position stand calls creatine monohydrate "the most effective ergogenic nutritional supplement currently available to athletes," reports that performance of high-intensity or repetitive exercise "is generally increased by 10–20%," and found no detrimental effects in healthy people in studies running up to five years: a performance endpoint replicated across decades and labs, which is why the rubric puts it at 5. Funding: the position stand was prepared with support from the Council for Responsible Nutrition and several authors disclose ties to supplement companies, which the score survives because the trial base is so wide; USADA is plain that creatine is not prohibited, while warning that any supplement carries a contamination risk.

Protein supplementation

Morton and colleagues pooled 49 randomized trials of protein supplementation during at least six weeks of resistance training, 1,863 healthy adults in all: protein added 0.30 kg of fat-free mass, 2.49 kg to one-repetition-maximum strength and 310 µm² of muscle-fibre cross-sectional area, with a larger fat-free-mass effect in resistance-trained people (+0.75 kg) and no further gain once total protein intake passed about 1.6 g per kilogram of body weight per day, a finding of the meta-analysis rather than a recommendation from this page. Strength, size and a trained-subject signal from 49 trials is what a 5 looks like; one senior author reports support from the US National Dairy Council, which also funded some of the pooled trials.

Collagen peptides

This is the row the supplement aisle means by "peptides," and it is a different legal category from everything below it: a food-grade protein hydrolysate, not an injectable research compound. Three randomized trials anchor the score, two from the University of Freiburg (Zdzieblik 2015, Jendricke 2019) and one from Ruhr University Bochum with the German Sport University Cologne (Kirmse 2019); all three used Gelita AG's product. In 53 sarcopenic men averaging 72 years, twelve weeks of resistance training plus collagen peptides produced a larger fat-free-mass gain (+4.2 vs +2.9 kg) and a larger isokinetic quadriceps-strength gain (+16.5 vs +7.3 Nm) than placebo, both P < 0.05. In 57 recreationally active young men, fat-free mass rose more on collagen (+2.0 vs +0.7 kg) but there was no between-group difference in strength or type-II fibre cross-sectional area; the authors attribute the difference to "passive connective tissue adaptations." In 77 premenopausal women, the only women-only muscle RCT on this page, collagen produced significantly larger fat-free-mass and hand-grip-strength gains than placebo; leg strength rose in both groups with no significant between-group difference.

Funding: Gelita AG supplied the product and paid participant compensation and sample analysis in the 2015 trial, per a 2025 corrigendum that also discloses a co-author's patent application on the substance; the 2019 men's trial was financed by the Collagen Research Institute with Gelita-supplied product; the 2019 women's trial states "no external funding" on its funding line while its acknowledgments say it was in part funded by Gelita, which also supplied the product. Fat-free mass up in all three, strength up in two, fibre size measured once and unchanged, one product supplier behind every trial and two named funders. That is a 3.

Tesamorelin

Tesamorelin is the only FDA-approved drug on this page, and its approval has nothing to do with lifting. The EGRIFTA SV label limits it to "the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy," says it "is not indicated for weight loss management as it has a weight neutral effect," and notes that long-term cardiovascular safety has not been established. In its two 26-week trials, lean body mass moved +1.3 kg vs −0.2 kg and +1.2 kg vs −0.03 kg against placebo. No strength or function test was reported. An exploratory secondary analysis of those trials, restricted to participants whose visceral fat had already responded, found small increases in CT-measured trunk-muscle area (total area +0.44 to +0.46 cm², lean area +0.64 to +1.08 cm²) and density in 193 responders versus 148 placebo participants; a responder-only analysis in HIV patients is a long way from a hypertrophy trial in healthy adults. Label warnings include neoplasms, elevated IGF-1, fluid retention and glucose intolerance. The pooled phase-3 abstract reports visceral fat, lipids and IGF-1 but no lean-mass figure; the label is the source used here.

MK-677 (ibutamoren)

Not a peptide. PubChem records ibutamoren as a spiro-indole sulfonamide small molecule, C27H36N4O5S; WADA files it under "growth hormone secretagogues and their mimetics." The best trial is Nass 2008: 65 healthy adults aged 60–81, randomized, two years with the primary endpoints read at twelve months. Fat-free mass rose 1.1 kg against a 0.5 kg loss on placebo, and the authors' own sentence: "Increased fat-free mass did not result in changes in strength or function" — with their caveat that the study was not powered to detect functional change. Body weight rose 2.7 kg vs 0.8 kg, fasting glucose rose 5 mg/dL, insulin sensitivity fell, and appetite increase, edema and muscle pain were reported. NIH funded the study; Merck supplied the drug and placebo. On the FDA compounding page, ibutamoren is category 2 under both 503A and 503B "due to the potential for congestive heart failure," citing a hip-fracture trial stopped early on that signal.

CJC-1295

PubMed holds two clinical-trial records, both from 2006 and both in healthy adults, and neither measured muscle. Teichman and colleagues reported two randomized, placebo-controlled dose trials in which GH rose two- to ten-fold and IGF-1 1.5- to three-fold; Ionescu and Frohman reported an uncontrolled single-injection study of GH pulsatility. Three of the six Teichman authors were at ConjuChem, the developer, per the journal's author list. On the FDA page, CJC-1295 now sits in the "nominated but withdrawn" table, with the agency's retained note of serious adverse events "including increased heart rate and systemic vasodilatory reaction" and "limited" clinical data; it is on no approved compounding list. A 1: no human muscle-relevant outcome has ever been published.

Ipamorelin

The foundational paper is a Novo Nordisk pharmacology study in cell preparations, anesthetized rats and swine; it contains no human data. The only randomized human trial ran in 117 bowel-resection patients for post-operative ileus and found no significant difference from placebo on any efficacy measure. The other human record is a 1999 pharmacokinetic study in healthy male volunteers, eight per dose level, that measured drug and GH concentrations only. FDA keeps ipamorelin acetate in category 2 for 503B compounding, citing a published report of "serious adverse events including death" in that gastric-motility setting. That is the entire human record of the compound that headlines the vendor roundups Google's AI Overview cites.

Sermorelin

At least one page in the same results — Gameday Men's Health's roundup, organic result seven for this query when checked September 5, 2026 — labels sermorelin "FDA-approved for GH deficiency." It was, until June 18, 2009; it is not today. The Federal Register records that both Geref approvals (pediatric GH deficiency and diagnostic use) were withdrawn effective June 18, 2009 at the manufacturer's request; any sermorelin dispensed today is compounded. Its 29 clinical-trial records are mostly GH-secretion, diagnostic and pediatric-growth studies, and no title mentions muscle, strength or body composition; one abstract does. Khorram and colleagues gave a Nle27-substituted GHRH(1-29) analogue — a modified molecule, not sermorelin itself — nightly for four months to 19 adults aged 55–71 in a single-blind, placebo-controlled trial, and found lean body mass up in the 9 men but not the 10 women, with no strength test. A second study, indexed under GHRH(1-29) rather than sermorelin, gave sermorelin itself to 11 healthy men aged 64–76 for six weeks with no control group: 2 of 6 strength measures improved and DXA muscle did not change (Vittone 1997). Older adults, tiny samples, one study uncontrolled and the other a different molecule: that is a 1 with its data disclosed, matching the hub's score, not a dash.

GHRP-2, GHRP-6 and hexarelin

The 2018 review covering these growth-hormone-releasing peptides found "few studies examining clinically significant endpoints such as body composition, exercise tolerance, and quality of life" and safety data "limited due to the overall short durations and small sizes of most studies." FDA lists GHRP-6 in 503B category 2 for cortisol and blood-glucose effects, and GHRP-2 for reports of "death of critically ill study subjects, infection and pancreatitis, though causality has not been established."

IGF-1 LR3

Zero. No clinical-trial record exists under any of its names. WADA lists IGF-1 "and its analogues" under S2.3, and FDA has no compounding listing for it. Any ranking that places IGF-1 LR3 anywhere on a human evidence scale is extrapolating from cell culture.

BPC-157 and TB-500

Marketed for recovery rather than growth, but on most competing lists, so they get a row. A 2025 systematic review of BPC-157 in orthopaedic sports medicine found 36 studies, 35 of them preclinical; the one clinical report was a retrospective knee series in which 7 of 12 patients described relief lasting over six months, and "no clinical safety data were found." A separate 2025 review counts three published human studies totalling 28 people, none measuring muscle, speed or strength. The nine thymosin-β4 trial records are dry-eye, venous-ulcer, cardiac, renal-transplant-biomarker and healthy-volunteer studies, plus one review the filter catches; none has a skeletal-muscle endpoint. FDA's retained note says it "has not identified any human exposure data" for the TB-500 fragment. Both compounding nominations were withdrawn. WADA names BPC-157 under S0 and TB-500 under S2.3.

Why "lean mass" on a scan is not muscle

Every growth-hormone-axis number on this page is a lean-mass or fat-free-mass figure, and the rubric treats those as biomarkers for a reason. Liu and colleagues pooled 27 study samples of growth hormone given to 303 fit young adults: lean body mass rose 2.1 kg, "but strength and exercise capacity did not seem to improve," and recipients reported more soft-tissue edema and fatigue. MK-677 shows the same split. Fluid, connective tissue and organ mass all count as lean on a DXA scan, so until a trial pairs the scan with a barbell or a biopsy, a lean-mass gain is a hormone result, not a muscle result. There is a second gap: Healthline's medically reviewed explainer notes that no study has examined growth-hormone secretagogues in well-trained people, and the populations behind every number here are older adults, HIV patients, surgical patients or healthy volunteers. A ranking for lifters is being extrapolated from people who do not lift.

Why MuscleLedger does not publish a "best peptide stack"

A common version of this question asks for a stack. Google's AI Overview for both this page's query and the stack version (checked September 5, 2026) names CJC-1295 with ipamorelin as the stack, and the pages it cites — Peptidepedia, Musculoskeletal Key and Innerbody among them — do the same. We decline, for three reasons already on the table. No human trial has ever tested that combination, or any combination of these compounds, for muscle; the "standard stack" is vendor copy repeated until it reads as consensus. One half of it is in FDA's category 2 with a death cited in the agency's reasoning; the other half carries an FDA note of cardiovascular adverse events. And every compound involved is prohibited at all times under WADA S2.2.4, so a stack recommendation is a doping recommendation for any tested athlete. Our about page states the policy: research compounds are covered as research, never as instructions.

What would move a row

Creatine and protein are at ceiling; only a large, well-controlled null result would move them. Collagen needs a lab outside the Gelita and Collagen Research Institute orbit to show a strength or fibre-size difference; two such trials would take it to 4. Tesamorelin and MK-677 each need a randomized trial in healthy, trained adults with a one-repetition-maximum or muscle cross-sectional-area endpoint; the same study, run for any row scored 1, would be the first human muscle data behind it. For BPC-157 and TB-500 the bar is lower and still unmet: one controlled human trial with any muscle or recovery endpoint. The FDA page, the WADA List and the PubMed counts are re-checked at each refresh; the dates in the table header say when that last happened. Mechanism and side-effect detail per compound lives on our peptides for muscle growth hub; this page is the ranking, that one is the explainer.

Sources

• Kreider RB et al. ISSN position stand: safety and efficacy of creatine supplementation. J Int Soc Sports Nutr 2017. PMC5469049. Preparation supported by the Council for Responsible Nutrition; author industry disclosures.
• USADA. What do athletes need to know about creatine? usada.org.
• Morton RW et al. Br J Sports Med 2018;52:376–384. PMID 28698222. One author reports National Dairy Council support.
• Zdzieblik D et al. Br J Nutr 2015;114:1237–45. PMC4594048; corrigendum Br J Nutr 2025;134:440, PMC12580965. Gelita AG supplied product and paid participant and analysis costs; co-author patent application disclosed.
• Kirmse M et al. Nutrients 2019;11:1154. PMC6566878. Authors at Ruhr University Bochum and the German Sport University Cologne. Funded by the Collagen Research Institute; product supplied by Gelita AG.
• Jendricke P et al. Nutrients 2019;11:892. PMC6521629 (PMID 31010031). Acknowledgments state the study was in part funded by GELITA GmbH, which also supplied the product, although the Funding line reads "no external funding."
• EGRIFTA SV (tesamorelin) prescribing information, Theratechnologies. DailyMed.
• Falutz J et al. J Clin Endocrinol Metab 2010;95:4291–304. PMID 20554713. Abstract consulted; full text paywalled.
• Adrian S et al. J Frailty Aging 2019;8:154–159. PMID 31237318. Exploratory secondary analysis, responders only (193 tesamorelin vs 148 placebo).
• Nass R et al. Ann Intern Med 2008;149:601–11. PMID 18981485. 2-year modified-crossover RCT, 1-year primary endpoints. NIH-funded; drug supplied by Merck.
• Liu H et al. Ann Intern Med 2008;148:747–58. PMID 18347346.
• Teichman SL et al. J Clin Endocrinol Metab 2006;91:799–805. PMID 16352683; author affiliations at doi 10.1210/jc.2005-1536. Three of six authors at ConjuChem, Inc.
• Ionescu M, Frohman LA. J Clin Endocrinol Metab 2006;91:4792–7. PMID 17018654.
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• Khorram O, Laughlin GA, Yen SS. J Clin Endocrinol Metab 1997;82:1472–9. PMID 9141536. [Nle27]GHRH(1-29)-NH2 analogue; 10 women, 9 men; single-blind, placebo-controlled.
• Vittone J et al. Metabolism 1997;46:89–96. PMID 9005976. GHRH(1-29), 11 men, six weeks, no control group.
• Sigalos JT, Pastuszak AW. Sex Med Rev 2018;6:45–53. PMC5632578.
• Vasireddi N et al. HSS J 2025;21:485–495. PMID 40756949. Author device-industry disclosures.
• Regeneration or Risk? A narrative review of BPC-157. 2025. PMC12446177. No funding declared.
• PubChem CID 178024, ibutamoren. pubchem.ncbi.nlm.nih.gov.
• FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (content current as of April 22, 2026). fda.gov.
• Federal Register, March 4, 2013. Determination that Geref (sermorelin acetate) was not withdrawn for reasons of safety or effectiveness. govinfo.gov.
• WADA. The 2026 Prohibited List, valid January 1, 2026. wada-ama.org.
• Healthline. Peptides for bodybuilding, updated July 27, 2026. healthline.com. Secondary source, cited for its statement on trained populations.
• Gameday Men's Health. Best peptides for muscle maintenance, dated October 20, 2025. gamedaymenshealth.com. Accessed September 5, 2026; table cell reads "FDA-approved for GH deficiency."
• Google US search results and AI Overview for "best peptides for muscle growth" and "best peptide stack for muscle growth," captured through the DataForSEO SERP API on September 5, 2026. AI Overview references included Rite Aid, Peptidepedia, Musculoskeletal Key, Innerbody, Reddit and YouTube; Gameday Men's Health at organic position seven; Healthline at organic position five.
• NCBI E-utilities esearch, PubMed, September 5, 2026, with publication-type filters Clinical Trial or Randomized Controlled Trial. Method record: esearch example for CJC-1295. Pooled queries: (GHRP-2 OR GHRP-6 OR hexarelin OR pralmorelin) = 165; ("thymosin beta 4" OR "thymosin beta-4" OR "thymosin β4") = 9; sermorelin = 29 (includes PMID 9141536).