SARMGrowth hormone secretagogueGhrelin agonistNon-steroidalOral

Ibutamoren (MK-677, GH secretagogue)

Also known as MK-677 · MK677 · Nutrobal · Ibutamoren mesylate

Written by enwyReviewed 15 Jul 20262 sources0 comments

Ibutamoren (MK-677) is a non-peptide growth hormone secretagogue, not a SARM, that raises GH and IGF-1 by mimicking ghrelin. It is the most human-studied compound in this group, with trials in older adults, GH-deficient patients and others. Its hallmark effects are increased appetite, water retention and higher IGF-1; it does not suppress testosterone, so no steroid profile applies.

01 Overview

MK-677 orally stimulates the ghrelin receptor to increase pulsatile GH release and raise IGF-1, without the injections of GH or peptides. Human trials have examined effects on body composition, bone, sleep and IGF-1 in the elderly and in catabolic states, generally showing increased lean mass and IGF-1 but limited functional benefit.

Common and well-documented effects are strong hunger, fluid retention, mild oedema and occasional lethargy. There is concern about worsening insulin sensitivity and blood glucose with prolonged use. It is not androgenic and does not affect the HPG axis. It remains unapproved, prohibited in sport, and sold as a research chemical.

02 Mechanism

Ghrelin-receptor (GHSR) agonist that increases pulsatile growth hormone secretion and downstream IGF-1, without acting on the androgen receptor.

03 Dosing

Tier	Dose	Route	Notes
Light	10–15 mg/day	Oral	Lower anecdotal range; often taken at night.
Common	20–25 mg/day	Oral	Doses around 25 mg were used in trials to raise IGF-1.

04 Effects

Effect	Magnitude	Evidence
Increased GH and IGF-1Human trials consistently show increased GH secretion and higher IGF-1 levels.	IGF-1 raised substantially	Clinical
Increased lean body massTrials in older adults showed increases in lean mass, though functional gains were limited.	modest	Clinical
Increased appetiteMarked hunger via ghrelin-receptor activation; useful for bulking but unwanted for others.		Clinical
Improved sleep qualitySome studies and users report improved slow-wave sleep.		Observational

05 Side effects

Effect	Severity	Frequency	Evidence
Water retention and oedemaFluid retention, puffiness and occasional peripheral oedema are frequently reported in trials and anecdote.	Moderate	Very common	Clinical
Increased appetite / hungerPronounced increase in hunger, a direct pharmacological effect.	Mild	Very common	Clinical
Impaired insulin sensitivity / raised blood glucoseGH elevation can reduce insulin sensitivity and raise fasting glucose, a concern with prolonged use.	Moderate	Common	Clinical
Lethargy and joint discomfortFatigue, muscle stiffness or joint aches sometimes reported, consistent with elevated GH/IGF-1.	Mild	Common	Observational

06 Legal status

United States

Not FDA-approved; unlawful as dietary supplement

as of

Prohibited at all times by WADA

as of

07 References

MK-677 (ibutamoren) increases GH and IGF-1 in older adultsAnn Intern Med, 2008

Ibutamoren clinical literaturePubMed

08 Discussion0 comments

Create account

Discussion is moderated. No sourcing, vendor names or price talk — those comments are removed, and repeat posts are banned.

This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.