Peptides for muscle growth, ranked by human evidence

People searching for peptides for muscle growth usually want one thing: a compound that reliably adds muscle. The honest answer is that no peptide is FDA approved for muscle growth, only a handful have any human lean mass data, and every compound on this list is banned for tested athletes. The ones with the most human evidence either are not peptides, were abandoned over safety signals, or measured hormone levels rather than muscle.

This ranking follows our evidence grades. For muscle loss from illness or aging, our muscle wasting page covers the medical condition; for soreness and injury, see muscle recovery.

How we ranked muscle building peptides

We ordered the list by three criteria, in this order:

1. Evidence grade. Human randomized trials first, then animal-only work. Grades come from each compound's record.
2. How close the human data are to muscle. A trial that measured lean mass ranks above one that measured growth hormone levels, which ranks above one in an unrelated condition.
3. Lawful access. Within a tier, a compound with a lawful prescription route ranks above one with none.

We also give each entry's WADA status, because for tested athletes that answer is the same across the board. Statuses were verified on September 22, 2026.

The ranking at a glance

• Human trials with a lean mass result: 1 MK-677, 2 ACE-031, 3 sermorelin, 4 tesamorelin (lean body mass only, not muscle or strength).
• Human trials without a muscle result: 5 CJC-1295.
• Animal only for muscle: 6 follistatin-344, 7 ipamorelin, 8 IGF-1 LR3, 9 PEG-MGF, 10 BPC-157 (recovery).
• WADA: all ten prohibited.

1. MK-677 (ibutamoren)

• GradeEvidence: Human RCT
• StatusRegulatory: FDA Category 2, cannot be compounded
• WADAWADA: Prohibited

MK-677 is an oral ghrelin mimetic, a small molecule rather than a peptide, but it is sold alongside peptides and searched as one. In a 2-year randomized trial of 65 healthy older adults, fat-free mass rose 1.1 kg on MK-677 and fell 0.5 kg on placebo at 1 year, but it did not improve strength or function, and it raised fasting glucose, reduced insulin sensitivity, and caused more swelling and muscle pain. [1] In 24 obese men over 8 weeks, fat-free mass rose by about 3 kg with no change in fat mass. [2]

A trial in older adults recovering from hip fracture was stopped early after a possible heart failure signal. [3] FDA cited that risk when it placed ibutamoren in Category 2, where it remains, so no licensed pharmacy may compound it. [4] Compare it on ipamorelin vs MK-677 and sermorelin vs MK-677.

2. ACE-031 (ramatercept)

• GradeEvidence: Human RCT
• StatusRegulatory: Abandoned investigational drug
• WADAWADA: Prohibited

ACE-031 is a large fusion protein that blocks myostatin and related signals. In 48 healthy postmenopausal women, a single injection at the higher doses raised total lean mass by roughly 1 kg and thigh muscle volume by about 5% at day 29. [5] In boys with Duchenne muscular dystrophy, lean mass showed a non-significant upward trend, and the trial was stopped early for nosebleeds and small dilated blood vessels in the skin. [6] Development ended, it was never submitted for approval, and anything sold under the name is unverified. See follistatin-344 vs ACE-031.

3. Sermorelin

• GradeEvidence: Human RCT
• StatusRegulatory: No approved product; compounded under a contested reading
• WADAWADA: Prohibited

Sermorelin is a short version of the body's growth hormone releasing hormone. In a small trial of 19 adults aged 55 to 71, 16 weeks of nightly injections raised growth hormone and IGF-1, increased skin thickness, and improved lean body mass and insulin sensitivity in men only. [7] That is the closest thing to a muscle result for any growth hormone releasing peptide, and it is small and old.

The approved product, Geref, was discontinued, and FDA later determined it was not withdrawn for safety or effectiveness reasons. [8] Many 503A pharmacies compound sermorelin on the basis of that former approval, but whether that is lawful depends on how a state board reads it. See the sermorelin cost page and tesamorelin vs sermorelin vs ipamorelin.

4. Tesamorelin

• GradeEvidence: Human RCT
• StatusRegulatory: FDA approved for HIV lipodystrophy
• WADAWADA: Prohibited

Tesamorelin is the only compound on this list with a clear lawful prescription path. It is approved to reduce excess abdominal fat in adults with HIV and lipodystrophy. [10] Its phase 3 trials were built around visceral fat, which fell by 24 square centimeters at 26 weeks versus a small rise on placebo. [9] Lean body mass rose about 1.2 to 1.3 kg on the label trials, which did not separate muscle from water and did not measure strength. [10] Egrifta WR by prescription is the only lawful product: tesamorelin became a biologic in 2020, and biologics cannot be compounded under 503A. [11] [32] Use for muscle is off-label with no trial support. Our post on whether tesamorelin builds muscle goes deeper, and prices are on the tesamorelin cost page.

5. CJC-1295

• GradeEvidence: Human RCT for hormone levels only
• StatusRegulatory: No lawful path
• WADAWADA: Prohibited

CJC-1295 is a long-acting growth hormone releasing hormone analog. In healthy adults, single injections raised growth hormone 2 to 10 fold for 6 days or more and IGF-1 1.5 to 3 fold for 9 to 11 days. [12] A second study found that pulses of growth hormone persisted during continuous stimulation. [13] No trial has measured muscle, strength, or any clinical outcome, and development was discontinued. Its Category 2 nomination was withdrawn, but it is not on the bulks list, so there is no lawful basis to compound it. [4] The popular pairing with ipamorelin has never been tested as a combination; see the CJC-1295 and ipamorelin blend page and CJC-1295 vs ipamorelin.

6. Follistatin-344

• GradeEvidence: Animal only for the peptide
• StatusRegulatory: No lawful path
• WADAWADA: Prohibited

Follistatin-344 binds myostatin. Delivered as gene therapy, it increased muscle size and strength in monkeys. [14] The only human data are also gene therapy, not the injected peptide sold online: in 6 patients with Becker muscular dystrophy, 4 improved their 6-minute walk distance over a year, [15] and a similar open-label trial in 6 patients with inclusion body myositis reported walking gains. [16] No human trial of injected follistatin-344 exists.

7. Ipamorelin

• GradeEvidence: Human pharmacology only; animal only for muscle
• StatusRegulatory: No lawful path
• WADAWADA: Prohibited

Ipamorelin was described in 1998 as a selective growth hormone secretagogue based on animal work. [17] Its only randomized human trial tested bowel recovery after surgery in 114 patients and found no significant benefit. [18] One small human pharmacology study showed a single IV infusion releases growth hormone in healthy men, [31] but no human trial has measured body composition or muscle. The nominators withdrew it from Category 2, but it is not on the bulks list, so it cannot lawfully be compounded. [4]

8. IGF-1 LR3

• GradeEvidence: Animal only
• StatusRegulatory: Never listed
• WADAWADA: Prohibited

IGF-1 LR3 is an engineered IGF-1 analog. In catabolic rats it was more anabolic than native IGF-1. [19] There is no human study. The closest approved drug, mecasermin, is native IGF-1 for children with severe IGF-1 deficiency, and its label lists low blood sugar as the most common adverse reaction. [20] IGF-1 LR3 has never been placed on the bulks list and cannot lawfully be compounded.

9. PEG-MGF

• GradeEvidence: Animal only
• StatusRegulatory: Removed from Category 2, no active nomination
• WADAWADA: Prohibited

PEG-MGF is a pegylated copy of part of mechano growth factor, an IGF-1 splice variant. In cell culture, the MGF peptide drove myoblast proliferation. [21] In people, the natural gene product rose in thigh muscle after heavy resistance exercise in younger adults but not in older adults, [22] which says something about training, not about the injected product. No study has given PEG-MGF to a person. See IGF-1 LR3 vs PEG-MGF.

10. BPC-157 (for recovery)

• GradeEvidence: Animal only
• StatusRegulatory: Under review
• WADAWADA: Prohibited

BPC-157 is marketed for recovery rather than growth. Its best evidence is rat tendon work, [23] and human data are three small uncontrolled pilot reports with no control group; no randomized trial has reported. [30] In July 2026 the Pharmacy Compounding Advisory Committee recommended it for the 503A bulks list, but FDA has not published a final rule; follow it on the BPC-157 regulatory tracker. [25] The popular pairing with TB-500 has no combination trial; see the Wolverine stack page.

Which muscle peptides are banned for tested athletes?

All of them. WADA prohibits growth hormone releasing factors and secretagogues such as MK-677, sermorelin, tesamorelin, CJC-1295, and ipamorelin, along with IGF-1 analogues and mechano growth factors, under S2; myostatin inhibitors such as follistatin and ACE-031 under S4; and unapproved substances such as BPC-157 under S0. [29] Research chemical products are also a common source of contamination and mislabeling, which matters for anyone subject to testing.

Are muscle growth peptides legal?

Mostly no. Tesamorelin has a lawful prescription route as Egrifta WR (it cannot be compounded, because it is a biologic), sermorelin is compounded under a contested reading, and BPC-157 is waiting on an FDA rule. Everything else on this list has no active nomination, is not on the 503A bulks list, and is not a component of an approved drug. [26] The peptide legality hub explains the categories and the state rules.

What actually has human evidence for muscle growth

Training and diet. A meta-analysis of resistance training studies found a graded dose-response: more weekly sets were associated with larger gains in muscle size. [27] A second meta-analysis found that protein supplementation added about 0.3 kg of fat-free mass during training, with little further benefit above about 1.6 g of protein per kg of body weight per day. [28] Neither is exciting, but both rest on many human trials, which is more than any compound above can claim.

For muscle loss caused by illness, age, or disuse, the evidence and standard care are on our muscle wasting page. For soreness and injury, see muscle recovery.

The takeaway

The best peptides for muscle growth, judged by human evidence, are not very good. The strongest lean mass data sit with a non-peptide that FDA flags for heart risk and an abandoned drug that caused bleeding. The growth hormone peptides raise hormone levels but have not shown muscle or strength gains in trials. We will re-rank this list when a published human trial changes a grade.