MK-677 (Ibutamoren)

Overview

MK-677 (ibutamoren) is NOT a peptide — it is an orally active, non-peptide small molecule that mimics the hormone ghrelin at the GHS-R1a receptor and acts as a growth hormone secretagogue, producing sustained increases in growth hormone and IGF-1. It is not FDA-approved for any indication; despite reaching clinical trials (including for conditions such as frailty and growth hormone deficiency), it was never approved and development for general use was not completed. Human studies confirm it reliably raises IGF-1 and can increase lean body mass, but it has also been linked to increased appetite, fluid retention, and reduced insulin sensitivity / higher blood glucose. Marketed claims about muscle building, anti-aging, and sleep should be read against the lack of approval and the unresolved safety questions.

Commonly Reported Uses

These are uses commonly discussed or marketed by users and vendors — not a list of proven or approved benefits, and not a recommendation.

• Increasing growth hormone / IGF-1 and lean body mass (marketed claim; not FDA-approved)
• Muscle growth and bodybuilding (marketed claim; not an approved use)
• Anti-aging and body-composition support (marketed claim; not an approved use)
• Sleep quality (some human signal; not an approved use)

What to Track

Data points you and your clinician might monitor. For observation only — not a diagnostic protocol.

• Labs — IGF-1 (expected to rise) plus fasting glucose / HbA1c and fasting insulin, since insulin sensitivity can worsen
• InBody/DEXA — skeletal muscle mass and body-fat %; note that early weight gain can include water
• Smart scale — weight trend, interpreted with fluid retention in mind
• WHOOP — sleep stages and recovery score
• Subjective daily check-ins — appetite, swelling/edema, lethargy

Sources & References

1. [1]Ibutamoren — Wikipedia
2. [2]Ibutamoren (MK-0677) — PubChem
3. [3]List of drugs banned by the World Anti-Doping Agency — Wikipedia