How it works
It mimics ghrelin at the growth-hormone-secretagogue receptor, prompting GH release and raising IGF-1 — while, unusually for this class, being active as an oral tablet with a ~24-hour half-life.
The evidence
Studies document large increases in IGF-1 and GH, increased lean mass, deeper slow-wave sleep, and a strong appetite increase. But it is not approved for any use, and a clinical trial was terminated over a cardiac safety signal.
Safety
The notable concerns are insulin resistance and higher blood glucose (from sustained IGF-1 elevation), fluid retention, increased appetite, and the cardiac safety signal above. Anything that chronically raises GH/IGF-1 warrants caution and monitoring.
FAQ
No — it's a small-molecule ghrelin mimetic. It's grouped with peptides because it targets the same GH pathway, but chemically it's different.
Sustained IGF-1 elevation can reduce insulin sensitivity over time, potentially raising glucose — a reason bloodwork and clinical oversight matter.
Sources
This profile summarizes the following. Follow the links to read the originals — and remember that summaries age, so check for newer information.
- Ibutamoren (Wikipedia)
- MK-677 effect on somatic growth (PMC)
- Ibutamoren clinical evidence guide (Body Nutrition)
Inclusion here is not endorsement of any source's claims; several are cited so you can compare how different outlets characterize the same evidence.
Reviewed by Theo — part of the PepConnection crew.