What is MK-677?

What is MK-677?

MK-677 (ibutamoren, also called MK-0677 or LUM-201) is an oral small-molecule, not a peptide. It acts at the ghrelin receptor and stimulates growth-hormone (GH) release. Human studies demonstrate increased GH and insulin-like growth factor 1 (IGF-1), but those laboratory changes do not establish better physical function or a general anti-aging effect (older-adult endocrine study; older-adult clinical trial). FDA says ibutamoren is not approved.

What does the human evidence show?

Research population	Direct observation	Limit
65 healthy older adults	Higher GH/IGF-1 and fat-free mass at the one-year primary assessment	No significant strength or function gain detected, but the trial was underpowered for functional endpoints; no significant visceral- or total-fat reduction
Eight healthy volunteers under brief dietary restriction	Improved nitrogen balance	Surrogate measure, not demonstrated clinical muscle recovery
24 obese men over eight weeks	Higher fat-free mass; oral glucose-tolerance response worsened	No significant total- or visceral-fat reduction; short and small study
161 people after hip fracture	IGF-1 rose	No statistically significant functional-performance benefit

A separate randomized Alzheimer disease trial also raised IGF-1 without slowing clinical progression. These studies cover different populations and outcomes; their participant counts should not be added together to imply one large muscle, sleep, or anti-aging trial.

Is MK-677 still being studied?

Yes. The official registry lists a completed Phase 2 LUM-201 pediatric study with posted results and a recruiting Phase 3 study in children with growth-hormone deficiency, checked in September 2026. An older 68-child analysis explored predictors of growth response in a distinct earlier trial. These pediatric records do not establish treatment benefit in healthy adults, and an active study is not an approval. The former statement that all development was discontinued is outdated.

Safety and regulatory limits

In the 65-person older-adult study, fasting glucose rose and insulin sensitivity fell; increased appetite, transient mild edema, and muscle pain were also reported. FDA warns about potential glucose, fluid-retention and other risks without an incidence estimate. WADA’s 2026 Prohibited List names ibutamoren. This guide is a research summary, not medical or product-selection advice.