Last updated: March 2026
MK-677 (Ibutamoren) is an oral growth hormone secretagogue that mimics ghrelin to stimulate natural GH and IGF-1 release. Not a peptide — it's a small molecule you take by mouth. Once daily, 24-hour half-life, ~40% IGF-1 increase.
MK-677 is a ghrelin receptor (GHSR-1a) agonist. By activating the ghrelin receptor, it stimulates growth hormone secretion from the pituitary gland — WITHOUT requiring deep sleep or exercise. The result is elevated GH and IGF-1 levels throughout the day.
MK-677 crosses the blood-brain barrier and selectively binds to the ghrelin receptor (GHSR-1a). This is the same receptor activated by the "hunger hormone" ghrelin. Unlike native ghrelin which has a half-life of ~30 minutes, MK-677 has a 24-hour half-life, providing sustained receptor activation.
MK-677 amplifies the body's natural GH pulses without disrupting the pulse pattern. Studies show it increases GH pulse amplitude by ~40% while maintaining normal pulse frequency. This leads to elevated 24-hour GH profiles and subsequently increased IGF-1 production from the liver.
Many users report improved sleep quality and increased REM sleep. This makes sense mechanistically — GH is primarily secreted during deep sleep (stages 3-4). By amplifying GH pulses, MK-677 may enhance the physiological GH surge that naturally occurs during sleep.
Since MK-677 mimics ghrelin, increased appetite is a common side effect. This can be beneficial for those trying to build muscle or recover from illness/wasting, but may be undesirable for weight management goals. Appetite effects typically persist throughout use.
MK-677 has been studied in multiple clinical trials for GH deficiency, muscle wasting, and obesity.
⚕️ Always consult a healthcare provider before starting any peptide protocol.
Standard research dosing is 10–25 mg taken orally once daily, ideally before bed. Evening dosing aligns with the body's natural overnight GH secretion window and helps soften the appetite-stimulating effects since most of the hunger drive occurs while asleep.
Clinical research has shown approximately a 50% increase in slow-wave (deep) sleep duration with MK-677 use. Slow-wave sleep is when the bulk of the body's endogenous GH secretion occurs, making this a meaningful additive effect — more deep sleep and more GH during that sleep window.
One important distinction: MK-677 activates the ghrelin receptor tonically — it doesn't produce the discrete, pulsatile GH release that mimics natural physiology. Natural GH is secreted in sharp pulses with low troughs between them. MK-677 produces a more sustained, non-pulsatile elevation. This isn't necessarily harmful, but it's a different signal pattern than injectable secretagogues like CJC-1295 + Ipamorelin deliver.
Significant appetite increase is the most consistent complaint with MK-677 — because it's literally mimicking the hunger hormone. This affects roughly 70% of users. For those in a muscle-building phase, the extra appetite can be useful. For anyone managing weight, it's a serious liability. There is no good way to eliminate this effect without compromising the ghrelin receptor activation that drives GH release.
MK-677 can raise fasting blood glucose and has been shown to elevate cortisol by approximately 2.3× in some studies. Both effects are relevant for anyone with insulin resistance or metabolic concerns. Regular fasting glucose monitoring is advisable during use, and anyone with pre-diabetes should approach MK-677 with significant caution.
A notable concern in the research community involves prolonged ghrelin receptor internalization from chronic MK-677 exposure. When a G-protein coupled receptor is continuously activated, it can internalize (be removed from the cell surface) in ways that may not fully reverse. The clinical significance of this in humans with MK-677 specifically is not yet established, but it is a legitimate reason to cycle and avoid indefinite continuous use.
8 weeks on, 4 weeks off is the most common cycling framework for MK-677. During the off period, blood glucose typically normalizes. Monitor fasting glucose before and during each cycle — if it trends significantly above your baseline, consider reducing dose or extending the break. Monthly cost from research sources runs approximately $40–80, making it one of the more accessible GH secretagogue options.
Combining with injectables: MK-677 can be layered with injectable GH secretagogues (CJC-1295, Ipamorelin, GHRP-2) at reduced doses of each. The rationale is that the GHRH axis (injectable side) and ghrelin axis (MK-677 side) are separate pathways — dual activation can amplify total GH output. When combining, most practitioners reduce MK-677 to 10 mg and cut injectable doses to roughly half to avoid excessive IGF-1 elevation.
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This page is for educational purposes only. It is not medical advice. MK-677 is not FDA approved for human use. It is sold as a research chemical only. Always consult a qualified healthcare provider before starting any supplement or research chemical.