Ibutamoren (MK-677, GH secretagogue)
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 | Countermeasures |
|---|---|---|---|---|
| Increased appetite / hungerPronounced increase in hunger, a direct pharmacological effect. | Mild | Very common | Clinical | |
| Lethargy and joint discomfortFatigue, muscle stiffness or joint aches sometimes reported, consistent with elevated GH/IGF-1. | Mild | Common | Observational | |
| Water retention and oedemaFluid retention, puffiness and occasional peripheral oedema are frequently reported in trials and anecdote. | Moderate | 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 |
06 Commonly used with
What ibutamoren is combined with, and why. This is about intent rather than safety — the interactions table below covers what is dangerous. Nothing here is listed without what it costs.
| Compound | Frequency | Purpose & trade-off |
|---|---|---|
| Stacked compounds | ||
| Ostarinerecomp | Ibutamoren is stacked with ostarine for GH-driven recovery, sleep and appetite while ostarine handles the anabolic side of a recomp.Trade-off: Ibutamoren is not suppressive and needs no PCT, but ostarine does, and ibutamoren adds water retention and hunger of its own. | |
| Testolonebulk | Added to a testolone bulk for appetite and recovery support to help sustain a caloric surplus and training volume.Trade-off: Ibutamoren itself requires no PCT, but it worsens water retention and can reduce insulin sensitivity over longer runs. | |
| Ligandrolmass | Combined with ligandrol so GH-mediated recovery and sleep support a mass phase driven by the SARM.Trade-off: Ligandrol brings suppression and a PCT requirement that ibutamoren does not, and ibutamoren's water retention can blur lean gains. | |
| Cardarinerecovery | Paired with cardarine for a non-hormonal combination aimed at recovery, sleep and endurance without any hormonal suppression.Trade-off: Neither is suppressive so no PCT is needed, but cardarine carries the rodent carcinogenicity concern and both lack long-term human data. | |