MK-677
Ibutamoren — orally-active ghrelin receptor agonist
An orally-active ghrelin receptor agonist developed by Merck. Drives GH pulse amplification and IGF-1 elevation similar to Ipamorelin but with a different convenience profile — daily oral pill instead of injection. Trade-off: pronounced hunger increase and water retention vs the injectable peptide alternatives.
Quick reference
How MK-677 works
MK-677 binds the ghrelin receptor (GHS-R1a) and triggers GH pulse amplification — same downstream pathway as injectable Ipamorelin, but with oral bioavailability that no injectable ghrelin-receptor peptide has matched. This is the convenience advantage.
Trade-offs vs Ipamorelin: the ghrelin arm includes hunger / appetite stimulation (Ipamorelin is the only ghrelin agonist that selectively bypasses this), water retention (often 3-5 lbs in first 2 weeks), and mild prolactin / cortisol elevation at higher doses. For a non-injection-tolerant user, these trade-offs are often acceptable; for a tested athlete or someone with hunger control issues, injectable Ipamorelin is the better choice.
Sleep depth improvement is one of the most consistently-reported benefits — most users describe deeper N3 sleep and more vivid dreams within 5-7 days. This is mechanistically similar to Ipamorelin's effect (REM sleep is GH-pulse-coupled).
In the DoseCraft framework, MK-677 targets ATP Shortage (improved sleep + IGF-1 → mitochondrial recovery) and indirectly Inflammation (better sleep reduces systemic inflammatory load).
Safety + side-effect profile
Generally well-tolerated for short-term use. The hunger and water-retention effects are the most-reported barriers to ongoing use.
Not documented at standard doses: hepatotoxicity, significant cardiovascular changes. Contraindications: type 2 diabetes (MK-677 transiently impairs insulin sensitivity), congestive heart failure (water retention can worsen volume status), pregnancy, lactation, active cancer therapy.
Interaction notes: do not stack with CJC-1295 + Ipamorelin or other GH secretagogues simultaneously — diminishing returns and theoretical receptor desensitization. Caution with diuretics (water retention may mask dehydration). Avoid late-night high-fat meals near dosing — slows absorption.
Insulin sensitivity caveat: MK-677 transiently reduces insulin sensitivity during active dosing. Most users normalize within 4 weeks of stopping. Monitor fasting glucose in long-term users; consider cycling rather than continuous dosing for metabolic safety.
- • Pronounced hunger increase, especially first 2-3 weeks
- • Water retention (typically 3-5 lbs in first 2 weeks, plateaus)
- • Vivid dreams + deeper sleep (intended effect)
- • Transient mild lethargy first 5-7 days
- • Occasional hand / foot tingling at higher doses (water-retention related)
- • Fasting glucose elevation in some users (transient)
Frequently asked
What is MK-677?
MK-677 (Ibutamoren) is an orally-active ghrelin receptor agonist developed by Merck. Drives GH pulse amplification and IGF-1 elevation. Available as capsule or liquid, typically dosed once daily before bed.
What is the typical MK-677 dose?
Standard practitioner protocol: 10-25 mg orally daily, before bed. Lower end (10 mg) for sleep + mild IGF-1 boost; higher end (25 mg) for full GH-axis activation. Take on an empty stomach when possible (high-fat meals slow absorption).
MK-677 vs CJC-1295 + Ipamorelin — which is better?
MK-677 wins on convenience (oral vs injectable). CJC + Ipa wins on side-effect profile (Ipamorelin selectively bypasses the hunger / cortisol effects that MK-677 has). For a non-injection-tolerant user, MK-677 is reasonable. For maximum efficacy with minimal side effects, CJC-1295 + Ipamorelin is the practitioner standard.
How much weight will I gain on MK-677 from water retention?
Typically 3-5 lbs in the first 2 weeks, then plateaus. This is intracellular water (driven by IGF-1) — not bloat. It mostly disperses within 1-2 weeks of cessation. Don't confuse this with fat gain.
Does MK-677 cause permanent insulin resistance?
No. MK-677 transiently reduces insulin sensitivity during active dosing. Most users normalize fasting glucose and HOMA-IR within 4 weeks of stopping. For long-term users, cycling (8-12 weeks on, 4 weeks off) preserves insulin sensitivity. Type 2 diabetics should generally avoid it.
How long until I see results?
Sleep quality improvements within 5-7 days. IGF-1 elevation measurable on bloodwork at 4-6 weeks. Body composition changes (lean mass gain, mild fat loss in some, weight gain from water in most) take 8-12 weeks. Skin / hair / nail benefits often visible at 6-8 weeks.
Should I cycle MK-677?
Yes. Standard cycling: 8-12 weeks on, 4 weeks off. Continuous use beyond 16 weeks risks pituitary desensitization and ongoing insulin sensitivity reduction. Cycling allows full endocrine recovery.
Are there long-term safety concerns?
Long-term safety data is limited (most published trials are 12-24 weeks). Documented at standard doses: hunger, water retention, transient insulin resistance, occasional fasting glucose elevation. Not documented at standard doses: hepatotoxicity, hormonal disruption beyond the GH-axis, cardiovascular adverse events.
Related compounds
Often researched, stacked, or compared with MK-677.
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