Quick Facts
Plain-English Summary
MK-677 is an orally active ghrelin receptor (GHSR-1a) agonist. Unlike peptide-based GHRPs (e.g., ipamorelin, hexarelin) that require subcutaneous injection and have short half-lives, MK-677 is a once-daily oral compound with a ~24-hour half-life that sustains elevated GH pulsatility and IGF-1 throughout the day. This pharmacokinetic profile made it attractive as a potential treatment for growth hormone deficiency, sarcopenia in the elderly, and catabolic states.
Human clinical trial data exists — a significant differentiator from most research peptides. Studies in elderly patients and GH-deficient adults confirmed robust, sustained IGF-1 elevation (20–40% increases). Improvements in lean mass, bone mineral density, and sleep architecture (particularly REM and slow-wave sleep) were documented in short-to-medium term trials.
However, commercial development was abandoned. A Phase III trial in elderly hip fracture patients was stopped early after an imbalance in congestive heart failure events in the treatment arm. While this population was elderly and frail (not reflective of typical biohacker users), it raised regulatory flags. The compound also consistently increases fasting blood glucose and insulin levels — a relevant concern for anyone with metabolic risk factors.
Metabolic warning: MK-677 reliably elevates fasting glucose and insulin resistance in clinical trials. Users with pre-diabetes, metabolic syndrome, or who are insulin-sensitive should approach with significant caution. This is not a vendor claim — it is documented in peer-reviewed RCTs.
The compound is not a SARM despite being commonly sold alongside them. It does not bind androgen receptors. Its mechanism is exclusively through ghrelin receptor agonism. Long-term safety beyond 12 months remains unknown in published literature.
Mechanism of Action
Proposed mechanisms below are derived from in vitro and rodent studies only. No mechanistic pathway has been validated in a controlled human study.
All mechanistic data is derived from in vitro or rodent studies. Applicability of these pathways in humans is not established.
Animal Data
| Model | Finding | ICPS Status |
|---|---|---|
| Rat — sarcopenia model | MK-677 oral dosing increased lean body mass and muscle cross-sectional area in aged rats; normalized to levels seen in young animals at 8 weeks. Chapman et al. 1996 ↗ | Preclinical |
| Rat — GH deficiency | Restored GH pulsatility and IGF-1 to normal range in hypophysectomized rats with once-daily oral dosing. Confirmed oral bioavailability and receptor selectivity. | Preclinical |
| Dog — bone metabolism | Improved bone mineral density and bone turnover markers after 12-month oral treatment. Supported rationale for human osteoporosis trials. | Preclinical |
No finding from this section has been replicated in a controlled human trial. Animal-to-human translation for peptides is uncertain and cannot be assumed.
Human Trials
| Trial | Population | Status | ICPS Status |
|---|---|---|---|
| RCT — elderly sarcopenia (Chapman et al.) | Adults 60–81 years (n=32) | — | RCT |
| RCT — obese adults (Copinschi et al.) | Healthy obese men (n=24) | — | RCT |
| Phase III — hip fracture (Nass et al.) | Elderly patients post hip fracture (n=595) | — | Halted |
| RCT — GH deficiency adults | Adults with GH deficiency (n=24) | — | RCT |
MK-677 has no FDA, EMA, or Health Canada–approved indications and no published Phase III trial data for any condition as of 2026.
Safety & Side Effects
Consistently documented in trials: increased fasting blood glucose, insulin resistance, increased appetite (expected ghrelin effect), fluid retention, and transient limb edema. These are pharmacological effects, not rare adverse events — they occur in the majority of users at therapeutic doses.
Phase III halt due to congestive heart failure imbalance in elderly frail patients. Not confirmed in younger populations but not investigated either. Sustained GH/IGF-1 elevation may increase cardiac workload. This is an unresolved signal that warrants caution.
- Intense hunger / food cravings
- Water retention / puffiness
- Lethargy or fatigue (first 2–4 weeks)
- Carpal tunnel-like symptoms
- Vivid dreams / deep sleep
- Active or suspected malignancy (IGF-1 is mitogenic)
- Diabetes or pre-diabetes
- Heart failure or cardiac disease history
- Pregnancy or breastfeeding
- Children and adolescents
MK-677 is not approved by the FDA, EMA, or Health Canada for any medical indication. It is classified as a research compound and is not legal for human therapeutic use in most jurisdictions. Procurement and use outside of registered clinical trials carries regulatory and unknown health risks.
References
Research disclaimer. CompoundProfile publishes summaries of available scientific literature for educational purposes only. This page does not constitute medical advice and should not be interpreted as an endorsement of MK-677 for any therapeutic use. Consult a licensed healthcare professional before considering any research compound. All evidence gradings reflect the state of published literature as of August 2026 and are assessed independently by ICPS.
Community Commentary
Selected discussion from r/Peptides · Curated for signal, not volume
MK-677 is the most consistent compound I've used for sleep. Third night in I was getting the most vivid dreams of my life and waking up feeling genuinely rested. Hunger was insane week 1–2 though. Gained about 5 lbs of water in the first week. Worth it for the sleep alone for me but know what you're getting into with the glucose stuff.
Ran bloodwork before and after 3 months of 12.5mg/day. IGF-1 went from 165 to 248 ng/mL. Fasting glucose went from 86 to 97 mg/dL — still normal but trending toward pre-diabetes territory. The trials showed this too. I stopped and glucose returned to baseline in 6 weeks. Not something I'd want to run indefinitely.
PSA: MK-677 is NOT a SARM. It doesn't touch androgen receptors. Vendors mislabel it constantly. It's a ghrelin mimetic. That said it's one of the most studied compounds in this space — actual human RCT data is rare. Read the Nass 2008 paper though, the cardiac halt should be in every discussion about long-term use.
The convenience of oral dosing is the killer feature. I ran GHRP-6/CJC before and the 3x/day injection schedule was brutal to maintain. MK-677 is one pill, incredible sleep, measurable IGF-1 bump. The hunger and water weight are the price you pay. Anyone who says there are no downsides hasn't actually run it.