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MK-677 (Ibutamoren)

Aliases: Ibutamoren · Nutrobal · MK-0677

Last verified: 2026-09-23

Clinical trialsModerate evidenceSmall moleculesHigh interest

The short version

MK-677 (ibutamoren) is an oral ghrelin mimetic that raises GH and IGF-1 in humans — confirmed in multiple placebo-controlled studies. But development stalled: the GH effect is real, while the body-composition effect is unconvincing (2 kg of 'lean mass' in 2 months, mostly water; the fracture trial failed). A classic 'biomarker works, clinic doesn't' case. It is popular in the 'biohacking' community regardless; increased appetite, water retention and elevated cortisol are commonly reported.

Identity & type

Molecular type
small-molecule
Sequence / structure
— (nuklearni secretagogue)
Molecular weight
~529 Da
Formula
C27H36N4O5S
Origin
Non-peptide (spiroindoline) growth hormone secretagogue, GHS-R1a agonist; orally active.

Mechanism of action

GHS-R1a agonism → pulsatile GH release; increases appetite (ghrelin effect) and deep sleep.

Dosing & routes

Official / clinical context

No approved official document exists for MK-677 (Ibutamoren). Any protocols mentioned are to be read as information, not as a recommendation.

Regulator-approved labeling and published study designs — never a recommendation.

Community-reported practice

10–25 mg/day orally. Most commonly reported: pronounced appetite, deeper sleep (REM/deep), fuller musculature and water retention in the first 2 weeks; in some users daytime lethargy and elevated blood sugar after months.

Unverified self-reports. Not medical advice. Not endorsement.

Expected effects (community)

Most commonly reported: pronounced appetite, deeper sleep (REM/deep), fuller musculature and water retention in the first 2 weeks; in some users daytime lethargy and elevated blood sugar after months.

Protocol — official vs community

Official / label

No approved product. Studied orally at 10–25 mg daily (frailty, GH deficiency, sarcopenia trials).

  1. 01Start 10 mg daily; most trials used 25 mg daily

Duration: Trials ran 6–24 months; IGF-1 elevation is sustained but plateaued.

Oral ghrelin receptor agonist — no injections, but also no selectivity: hunger, transient cortisol/prolactin effects and insulin resistance accompany chronic use.

Community (anecdotal)

10–25 mg oral daily, usually at night (sleep-quality anecdote + GH pulse timing).

Cycle:
Controversial: many run 12–16 weeks to limit insulin resistance; others run it for months.
Break:
4 weeks minimum between cycles; fasting glucose check is the community-standard harm reduction.

The insulin-sensitizing concern is the most legitimate reason to cycle — chronic IGF-1 elevation + glucose impairment is a real metabolic trade.

Human evidence

Multiple placebo-controlled studies in older and younger adults confirmed GH/IGF-1 increases; fracture (phase IIb) and body-composition endpoints were not met.

Preclinical evidence

Preclinical literature preceded the clinical trials; details vary by compound.

Known risks

  • Increased appetite, water retention, edemacharacterized
  • Mild cortisol and prolactin increasescharacterized
  • Theoretical insulin-resistance risk with chronic usetheoretical

Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.

Unknowns & evidence gaps

  • Clinical benefit for any indication

Frequently asked questions

References

  1. Nass R. et al., MK-677 in healthy men (J Clin Endocrinol Metab, 2008)