Primary entity: MK-677 (Ibutamoren)Also known as: Ibutamoren; MK-0677; LUM-201; Nutrabol (folk)Class: performance-adjacent literacy (see page)Cluster: Performance-adjacent
MK-677 (ibutamoren) is an orally active growth hormone secretagogue that agonizes the ghrelin receptor (GHS-R1a), increasing endogenous GH and IGF-1 in studied settings — it is not a selective androgen receptor modulator. It is not a peptide, not FDA-approved as a consumer anti-aging or bodybuilding drug (developmental history includes discontinued Merck work and later Lumos LUM-201 programs for GH deficiency —), and is prohibited by WADA under S2.2.4 growth hormone secretagogues (not under the SARM/anabolic S1 section).
SARMs bind the androgen receptor. Ibutamoren binds the ghrelin / GH secretagogue receptor. USADA and FDA briefing materials explicitly note that MK-677 is often mislabeled as a SARM in online shops. Correct the class before any other comparison.
No FDA-approved ibutamoren consumer product for bodybuilding/anti-aging. WADA: ibutamoren (MK-677) listed under S2.2.4 GHS/mimetics alongside agents such as ipamorelin and anamorelin — prohibited at all times. Some jurisdictions treat supply strictly; Sport Integrity Australia describes ibutamoren as prohibited and notes poison-scheduling themes.
Key takeaways
- Not a SARM and not a peptide — oral GH secretagogue (ghrelin-receptor agonist).
- ≠ Ostarine (MK-2866) — different MK code, different pharmacology.
- Not FDA-approved for consumer physique/anti-aging use.
- WADA S2.2.4 (GHS), not S1.2 SARMs
- No dosage / “GH peaking” charts on this site.
Questions this page answers
Next questions we answer on this page (curiosity / AI-gap map):
- What is MK-677?
- Aliases / LUM-201
- Why shops call it a SARM
- What it is NOT
- Mechanism (ghrelin / GH)
- Evidence ladder
- What has been studied
- Safety literacy
- Regulatory & WADA
- Why no dosages
- Related (CJC / Ipamorelin)
- Who for / not for
Who is this profile for — and who is it not for?
For: readers who saw MK-677 in a “SARM stack” list and need the class correction, plus GH-axis adjacency to peptide secretagogues.
Not for: anyone seeking oral GH protocols, hunger-stack charts, or buy links.
What is MK-677?
Ibutamoren (MK-677 / MK-0677) is a spiropiperidine small molecule that mimics ghrelin at GHS-R1a, stimulating pituitary GH release and raising IGF-1 in clinical research contexts. Later development as LUM-201 targets pediatric GH deficiency pathways — that is a distinct regulated-development story, not permission for gray-market anti-aging use.
Adjacent peptide secretagogues: CJC-1295 / Ipamorelin.
| Chemistry class | Oral GH secretagogue (GHS-R1a agonist) |
|---|---|
| Peptide? | No |
| SARM? | No |
| WADA section | S2.2.4 GHS — (not S1.2) |
| MK confusion | ≠ MK-2866 (ostarine) |
Also known as
- Ibutamoren — drug name.
- MK-677 / MK-0677 — Merck-era codes.
- LUM-201 — Lumos development code for GH-deficiency programs
- Nutrabol
Online nickname— folk/vendor branding. - Mis-tags: “MK-677 SARM,” “ibutamoren peptide.”
False. Receptor: ghrelin/GHS-R1a, not AR. WADA files it under peptide hormones / growth factors / mimetics (S2), not other anabolic agents (S1.2). Shops that shelve it under SARMs are using retail taxonomy, not pharmacology.
How is MK-677 classified?
Investigational oral GHS / ghrelin mimetic — small molecule. Performance-adjacent + GH-axis literacy bridge to GHRP/GHRH peptide pages. Explicitly separated from the SARM set on this site.
What is MK-677 not?
| MK-677 is not… | Why that matters |
|---|---|
| A SARM | Different receptor (GHS-R1a ≠ AR) |
| A peptide | Small-molecule secretagogue |
| Ostarine / MK-2866 | Different MK code and class |
| Injectable GH | Raises endogenous GH/IGF-1 pathways; not recombinant GH vials |
| FDA-approved anti-aging pill | No such consumer approval |
| Something we dose | Refusal |
How is MK-677 thought to work?
Ghrelin-receptor agonism → GH pulse amplification → IGF-1 increases in studied human settings. Appetite (ghrelin-pathway) and metabolic effects appear in research narratives. Mechanism literacy ≠ approved indication.
What human vs animal vs label evidence exists?
| Evidence type | What exists (summary) | Maturity |
|---|---|---|
| Human clinical historical | Multiple clinical pharmacology / body-composition and GH-axis studies in various populations historically | Human Incomplete / not approved consumer label |
| Ongoing/related development | LUM-201 GH-deficiency programs | Human Developmental |
| Approved U.S. consumer label | None for ibutamoren bodybuilding/anti-aging | None |
| Forum sleep/hunger lore | Anecdote | None |
This page does not invent IGF-1 percentage claims.
What has MK-677 been studied for?
GH/IGF-1 axis, body composition, aging-related and deficiency-related developmental themes historically. Recreational “oral GH” use is not an approved labeled use.
What safety topics come up?
Research and secondary literature discuss appetite increase, edema/water retention themes, insulin-sensitivity concerns, and cortisol/prolactin monitoring discussions in clinical contexts — not a home protocol. Long-term gray-market safety is unestablished. Not medical advice.
What is MK-677's regulatory status?
- U.S.: No approved ibutamoren product for general anti-aging/bodybuilding. FDA PCAC materials have discussed ibutamoren in compounding contexts historically — recommendation ≠ approval
- WADA: S2.2.4 growth hormone secretagogues — ibutamoren (MK-677) named
- Mislabeling: Often sold in “SARM” bottles — class error with enforcement implications for athletes.
Why doesn't this page include a dosage chart?
“MK-677 dosage for height / anti-aging / recomp” queries are protocol-seeking. Refusal.
Related lab literacy
Oral small molecule — peptide reconstitution N/A. GH-axis peptide literacy: CJC-1295 / Ipamorelin.
Related compounds and comparisons
- CJC-1295 / Ipamorelin — peptide GHRH/GHRP secretagogue literacy (different entities).
- Ostarine — MK-2866 SARM (disambiguation).
- RAD-140 / LGD-4033 — true SARMs often co-shelved incorrectly with MK-677.
Frequently asked questions
Is MK-677 a SARM?
No. It is a ghrelin-receptor agonist / GH secretagogue.
Is MK-677 a peptide?
No. It is a small molecule.
Is MK-677 the same as ostarine?
No. Ostarine is MK-2866, a SARM.
Where does WADA list it?
Under S2.2.4 growth hormone secretagogues — not S1.2 SARMs.
Is it FDA approved?
Not as an approved consumer anti-aging/bodybuilding drug.
Why no dosage chart?
YMYL refusal for unapproved endocrine self-experimentation.
Not a SARM, not a peptide, WADA S2-relevant, not medical advice. Disclaimer..
Sources
The sources below were checked against PubMed, DailyMed, or the official agency page on November 10, 2026 (America/Phoenix). Links go to the publisher, PubMed, or the agency record.
- Primary — human Nass R, Pezzoli SS, Oliveri MC, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008. doi:10.7326/0003-4819-149-9-200811040-00003. PMID: 18981485.
- Primary — human Adunsky A, Chandler J, Heyden N, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011. doi:10.1016/j.archger.2010.10.004. PMID: 21067829. The primary functional-performance analysis did not show a clear benefit versus placebo.
- Anti-doping World Anti-Doping Agency. The World Anti-Doping Code International Standard Prohibited List 2026. Accessed November 10, 2026. Confirm the current list and GlobalDRO before relying on sport status. The 2026 list names ibutamoren (MK-677) under S2 as a growth-hormone secretagogue. It is not a SARM.
- Written by
- Peptide Tutorials Staff — a group of independent researchers & writers (not clinicians)
- Published · Updated
- Oct 7, 2026 · Oct 7, 2026 · Regulatory and sport-status wording checked November 10, 2026 against current FDA labels and the 2026 WADA Prohibited List · How we source & update
Educational disclaimer: Educational only. MK-677 (ibutamoren) is not a SARM and not a peptide. Not FDA-approved for consumer physique use. No dosing or buy links. We don't sell peptides. Read our full disclaimers.