MK-677: Ibutamoren — oral growth-hormone secretagogue
An orally active ghrelin mimetic that raises growth hormone and IGF-1 — investigational, never approved, and known to raise blood sugar in trials.
What is MK-677?
MK-677 (ibutamoren) is an orally active growth-hormone secretagogue — a non-peptide ghrelin mimetic that raises growth hormone (GH) and IGF-1. Unlike the injectable GH peptides, it's taken by mouth, which is part of its appeal. It has been studied in clinical trials but was never approved, and a key finding is that it raises fasting blood glucose.
How MK-677 works (mechanism)
MK-677 activates the ghrelin receptor (GHS-R1a), stimulating pulsatile GH release and increasing IGF-1, with effects sustained by oral dosing. In a 2-year randomised trial in healthy older adults, 25 mg daily increased GH and IGF-1 toward youthful levels and increased fat-free mass — but also produced a sustained increase in fasting blood glucose and insulin resistance [1]. Earlier work showed prolonged oral MK-677 could also affect sleep and GH secretion [3].
Why it's studied / reported uses
Growth hormone, IGF-1 & body composition
MK-677 is studied for raising GH/IGF-1 and increasing fat-free mass; the 2-year Nass trial is the largest controlled human dataset [1][2]. It did not improve strength in that trial.
Appetite & sleep
As a ghrelin mimetic it increases appetite, and older research examined effects on sleep quality [3].
Dosing reported in studies
Route: oral
Ibutamoren, an orally active GH secretagogue studied in clinical trials.
Sources: Nass et al. (2008) — Ann Intern Med · Murphy et al. (1998) — JCEM
Investigational; can increase appetite, water retention and blood glucose. These figures reflect what studies or protocols reported — not a recommendation and not tailored to you.
Calculate a dose in the reconstitution calculator →Safety & side effects
MK-677 is investigational and not FDA-approved. The best-documented concern is a rise in fasting blood glucose and insulin resistance, seen over 2 years at 25 mg/day [1]. Other reported effects include increased appetite, water retention and lethargy. It is prohibited in competitive sport. People with, or at risk of, diabetes should be especially cautious. Consult a licensed physician.
Studies & references
- Effects of an oral ghrelin mimetic (MK-677) on body composition in healthy older adults — 2-year randomised trial — NCBI / PMC2757071 (Nass et al., Ann Intern Med 2008)
- Effects of an oral ghrelin mimetic on body composition (PubMed record) — PubMed 18981485
- MK-677, an orally active GH secretagogue — early clinical study — PubMed 9467534
Frequently asked questions
Is MK-677 FDA-approved?
No. MK-677 (ibutamoren) is investigational and was never approved for any indication. It is also prohibited in competitive sport.
Does MK-677 raise blood sugar?
Yes — in the 2-year Nass trial, 25 mg/day raised fasting glucose and reduced insulin sensitivity. People with or at risk of diabetes should be cautious and consult a doctor.
How is MK-677 dosed in studies?
The most-studied dose is 25 mg once daily (oral); community use often cites 10–25 mg/day (see the dosing section). This is not a recommendation.
Is MK-677 a SARM?
No. It's a growth-hormone secretagogue (ghrelin mimetic), often grouped with SARMs in the sports-supplement world but mechanistically different.
⚠ Research & educational use only. This page is compiled from published research and does not constitute medical advice. MK-677 is investigational and not FDA-approved for any use. Nothing here is a recommendation to use or a prescription. Safe use can only be determined by a licensed physician. Last updated 2026-07-06.