MK-677, or ibutamoren, is a nonpeptide small molecule studied as a ghrelin-receptor agonist and growth hormone secretagogue. It belongs to a different class from SARMs. Findings on fat-free mass in older adults must be distinguished from strength and fat-loss outcomes.
How does MK-677 differ from SARMs?
MK-677 acts at the ghrelin receptor, which is involved in GH release. SARMs concern the androgen receptor. Being discussed together does not make them the same class. Primary receptor research.
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| Term | Meaning | Keep separate |
|---|---|---|
| MK-677 / Ibutamoren | A nonpeptide GH secretagogue | Different from administering GH itself |
| SARMs | Androgen-receptor modulators | Evidence depends on the individual compound |
| Peptide | A description of amino-acid-chain structure | Not a shared clinical effect across all peptides |
What benefits were found in people?
A randomized trial by Nass and colleagues enrolled 65 healthy adults aged 60–81. MK-677 increased GH/IGF-1 and fat-free mass, but strength and function did not improve and abdominal visceral fat did not differ significantly. These findings do not establish bodybuilding outcomes in younger adults. Read the original trial.
Which adverse effects matter?
FDA describes increased appetite, fluid retention, fatigue, muscle pain and changes in glucose regulation or insulin sensitivity. FDA information on ibutamoren. A separate hip-fracture recovery trial ended early following a potential heart-failure safety signal. That context matters when interpreting risk; it does not establish the same risk for every population. The safety-signal context.
Understand status and prepare questions
FDA states that ibutamoren is not approved by that agency. This describes the United States and does not verify any Thai product registration. FDA’s stated status.
For a clinical discussion, bring the substance name, exposure dates, medicines, symptoms and earlier laboratory reports. Ask which assessment of glucose, fluid retention or other concerns is relevant to your history. This is an evidence guide, not an individualized treatment plan.
Frequently asked questions
Is MK-677 a SARM?
No. MK-677 acts at the ghrelin receptor; SARMs concern the androgen receptor.
Does increased fat-free mass always mean greater strength?
No. They are different outcomes. Strength and function did not improve in the cited older-adult trial.
Can MK-677 affect blood glucose?
Research identifies effects on glucose and insulin sensitivity. A clinician should interpret these alongside your history and results.