MK-677

From Retapedia, the free peptide encyclopedia
Medical disclaimer. This article is for informational purposes only and does not constitute medical advice. Consult a qualified clinician before considering any compound discussed below. See Retapedia : Medical disclaimer.

Summary

What it does
MK-677 (Ibutamoren) is used to add lean body mass, improve bone density, and deepen sleep. Reported side effects include more appetite, water retention, higher fasting blood sugar, and a weaker response to insulin; one clinical trial was stopped after serious heart problems in older patients.
How it works
A daily pill that copies ghrelin, the hunger hormone. It switches on the same receptor, so the pituitary gland releases more growth hormone and levels of IGF-1, a growth signal made in response to growth hormone, rise. It is not approved, and development appears to have stopped.
WADA status
Prohibited by the World Anti-Doping Agency (WADA). Drug-tested athletes cannot use it.

MK-677 (Ibutamoren) is a small molecule studied for its effects on growth hormone, muscle gain, and sleep. Oral ghrelin receptor agonist boosting GH/IGF-1 and sleep quality. Causes insulin resistance and glucose issues. Not FDA-approved, development discontinued.

Ibutamoren (MK-677) is a potent, long-acting, orally-active, selective non-peptide agonist of the ghrelin receptor (GHS-R1a) and growth hormone secretagogue. It mimics ghrelin's action by binding to receptors in the hypothalamus and pituitary gland, increasing growth hormone secretion by 50-97% and significantly elevating IGF-1 levels while preserving natural pulsatile GH secretion patterns. Clinical trials in elderly populations demonstrated significant increases in lean body mass (1.1 kg gain vs 0.5 kg loss with placebo over 12 months), improved bone mineral density, and enhanced markers of bone formation.

Natty status
MK-677 is classified as not natty. It is prohibited by WADA and most natural bodybuilding federations. Use places the athlete in the enhanced category. See § Natty status.
Contents [hide]
  1. 1 Overview
  2. 2 Mechanism of action
  3. 3 Reported effects
  4. 4 Dosage and administration
  5. 5 Natty status
  6. 6 Research
  7. 7 Related compounds
  8. 8 Frequently asked questions
  9. 9 References
  10. 10 External links

Overview

Notable for dramatically improving sleep quality with 20-50% increases in REM sleep and 50% increases in slow-wave sleep.

However, ibutamoren consistently impairs glucose metabolism, causing fasting blood glucose elevation, decreased insulin sensitivity, and increased HbA1c in multiple trials, leading to dose reductions or discontinuation.

One clinical trial was terminated due to serious adverse events including cardiovascular concerns and congestive heart failure cases in elderly patients.

Not FDA-approved and development appears discontinued due to safety concerns, particularly cardiovascular risks and metabolic effects.

Common side effects include increased appetite, water retention, insulin resistance, and potential increased cancer risk from elevated IGF-1.

Recommended 8-12 week cycles at 10-25mg daily, typically taken before bed for sleep benefits.

As a growth hormone secretagogue, it is prohibited by the World Anti-Doping Agency (WADA) both in and out of competition.

Mechanism of action

Oral ghrelin receptor agonist that raises growth hormone and IGF-1. Increases lean mass, bone density, and deep sleep. Causes insulin resistance and elevated blood sugar.

Reported effects

Effects reported in the literature and from preclinical models include:

  • Preliminary data have been reported for oral ibutamoren as a growth hormone secretagogue in children with partial growth hormone deficiency. [3] Anecdotal
  • Cryo-EM structures of the human ghrelin receptor bound to ibutamoren revealed the molecular basis of its binding and receptor activation. [5] Preclinical
  • In cell culture, ibutamoren reduced the viability of cancer cell lines with a functional MDM2-p53 pathway but not of lines carrying damaging mutations in that pathway. [6] Preclinical
  • A single 10 mg dose was detectable in a male volunteer's hair at 1.3 pg/mg four weeks later, and a user who took 60 capsules of 10 mg over 90 days tested positive at 224 pg/mg, establishing a minimal detectable dose for doping-control hair tests. [1] Anecdotal
  • A man in his early 30s developed transaminitis after taking MK-677 for 2 months, and liver function tests returned to normal after he stopped the supplement. [4] Anecdotal
  • A 54-year-old man with recent combined use of ibutamoren and the SARM RAD-140 had an atraumatic splenic rupture that needed embolization and splenectomy, with the compounds named only as speculative contributing factors. [2] Anecdotal

Evidence grades: FDA approvedApproved (non-US)Phase IIIPhase IIPhase IPreclinicalAnecdotal

Dosage and administration

⚠
Dosage information is included for encyclopedic purposes only. Retapedia does not provide medical advice. See Retapedia : Medical disclaimer.

Low dose

  • 10-15mg daily (ideal for sleep, longevity, first-time users)

Moderate dose

  • 20-25mg daily (clinical trial standard, body recomposition)

High dose

  • 30mg+ daily (advanced users, not recommended due to side effects)

Timing

  • Before bed: Maximizes sleep benefits, reduces daytime hunger
  • Morning: Increases appetite throughout day (useful for bulking)

Cycle duration

  • 8-12 weeks recommended, up to 16 weeks for intermediate

Half

  • life: 24 hours (once daily dosing sufficient)

General

  • Monitor fasting glucose and insulin sensitivity during use

Natty status

See also: Peptide § Natty status

MK-677 is classified as not natty. It appears on the WADA prohibited list and is banned by major natural bodybuilding federations.[7] Use of this compound places the athlete in the enhanced category rather than the natural category in competitive contexts.

Research

1 active clinical trial on record — highest phase: Phase 3. 8 registered in total , of which 5 completed
View on ClinicalTrials.gov · fetched Oct 24, 2026

The peptide has been the subject of 12 studies and reference works collected on this site. Additional bibliography is in § External links below.

Other peptides in this catalogue with overlapping mechanisms or status:

Ipamorelin Not natty
Selectively triggers growth hormone release without raising cortisol or prolactin. Human efficacy unproven: a Phase 2 trial failed and body-composition benefits remain preclinical. Subcutaneous injection.
5-Amino-1MQ Not natty
Oral small-molecule NNMT inhibitor that raises NAD+ and S-adenosyl methionine to boost fat-cell energy expenditure. Studied only in rodents for fat loss; no human trials exist.
AOD-9604 Not natty
Growth hormone fragment designed to promote fat breakdown without effects on growth, blood sugar, or IGF-1. A 24-week obesity trial found no significant weight loss over placebo.
Epithalon Not natty
Marketed as an anti-aging peptide. In preclinical studies it boosts telomerase activity, supports the body's own melatonin production, and shows antioxidant effects. Human evidence is minimal.

Frequently asked questions

What is MK-677?

Oral ghrelin receptor agonist boosting GH/IGF-1 and sleep quality. Causes insulin resistance and glucose issues. Not FDA-approved, development discontinued.

What is MK-677 used for?

MK-677 (Ibutamoren) is used to add lean body mass, improve bone density, and deepen sleep. Reported side effects include more appetite, water retention, higher fasting blood sugar, and a weaker response to insulin; one clinical trial was stopped after serious heart problems in older patients.

How does MK-677 work?

A daily pill that copies ghrelin, the hunger hormone. It switches on the same receptor, so the pituitary gland releases more growth hormone and levels of IGF-1, a growth signal made in response to growth hormone, rise. It is not approved, and development appears to have stopped.

Is MK-677 natty?

No. MK-677 is classified as not natty. It is prohibited by WADA and banned by most natural bodybuilding federations. Use places an athlete in the enhanced category.

Is MK-677 banned by WADA?

Yes. MK-677 is prohibited by the World Anti-Doping Agency (WADA), so drug-tested athletes cannot use it. Check the current WADA Prohibited List before competing.

How is MK-677 administered?

MK-677 is typically administered via: oral. Dosage and administration protocols vary; see the Dosage section for details.

References

  1. ^ Hair detection study for doping control
  2. ^ Spontaneous Splenic Rupture in a Patient With Recent Use of Performance-Enhancing Compounds: A Case Report and Literature Review.
  3. ^ New directions in growth hormone treatment in children. Recent review
  4. ^ Hepatotoxicity induced by MK-677. Recent
  5. ^ Structural basis of human ghrelin receptor signaling by ghrelin and the synthetic agonist ibutamoren. Recent
  6. ^ Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines. Recent
  7. a b World Anti-Doping Agency. (2026). Prohibited List 2026.

External links

Categories: Peptides | Performance-enhancing substances | Growth hormone | Muscle gain | Sleep | Bone density

This page was last updated on October 24, 2026, at 02:56 (UTC).

Research last reviewed on October 24, 2026.

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