MK-677
Also known as: Ibutamoren, MK-0677
By GLPeptideSciences Editorial Team · How we evaluate evidence · Reviewed by Dr. George S. Watson, MD, Cardiothoracic Surgeon · Updated 2026-06-02
An orally active ghrelin-receptor agonist (growth hormone secretagogue) that raises GH and IGF-1; a small molecule rather than a peptide, with some human study data.
What it is & how it works
What it is
MK-677, or ibutamoren, is an orally active growth hormone secretagogue — a ghrelin- receptor agonist that prompts the body to release more of its own GH and IGF-1. Notably, it’s a small molecule taken by mouth, not an injected peptide.
How it works
By activating the ghrelin receptor, MK-677 produces a sustained rise in GH and IGF-1. The oral route and long activity are what make it distinct from injectable secretagogues like ipamorelin.
Evidence and cautions
The GH/IGF-1 effect is well documented in humans, but it is not an approved therapy, and the fitness-context benefits people describe are largely anecdotal. The practical cautions — appetite, water retention, and effects on insulin sensitivity — are worth taking seriously.
What it's discussed & studied for
- Growth hormone / IGF-1 support
- Appetite, sleep, body composition (reported)
Discussion of a use is not a claim that it works or is approved.
Research status
Studied in humans across several contexts (it raises GH/IGF-1), but not approved as a therapy. Investigated and discontinued for some indications.
Evidence quality
Mixed. There is real human pharmacology showing it raises GH/IGF-1; outcome claims in fitness contexts are largely anecdotal, and it is not approved.
Dosing discussion
Discussed as a once-daily oral dose because it's orally active. This reflects community convention; it is not approved dosing guidance.
Educational summary of what is discussed in the literature and community — not a dosing recommendation or medical advice.
Safety & harm reduction
Commonly reported: increased appetite, water retention, and effects on insulin sensitivity / blood sugar. These warrant caution, especially with metabolic risk. Not approved.
Sourcing literacy
Orally active and a small molecule, but still unapproved and sold for research use. Verify identity and purity.
Selected literature
FAQ
Is MK-677 a peptide?
No — it's an orally active small molecule that mimics ghrelin. It's grouped with secretagogues because it raises GH the same way peptide secretagogues aim to.
What are the main cautions?
Increased appetite, water retention, and effects on insulin sensitivity and blood sugar are commonly reported. It is not approved.