MK-677
Ibutamoren — orally-active ghrelin receptor agonist
MK-677 (ibutamoren) is an oral, non-peptide drug that mimics ghrelin to raise growth hormone and IGF-1. It has been tested in human trials — including a 2-year trial in healthy older adults and a trial in Alzheimer's disease that found no effect on disease progression — but it is not approved for any use. Known downsides include increased appetite, fluid retention and higher blood sugar.
Quick reference
How MK-677 is dosed in practice
MK-677 is taken by mouth once a day, usually 10–25 mg. Many people take it at bedtime; the small sleep study that tested it used bedtime dosing.
Starting at 10 mg and moving up only if appetite, swelling and blood sugar stay manageable is common. Many run it for 8–12 weeks, then take about 4 weeks off, mainly to limit the effects on appetite and blood sugar.
Where the numbers come from: the human trials used 25 mg once daily — the top of the range. Lower amounts are practitioner convention. MK-677 is not an approved drug, so there's no label; if you have diabetes or prediabetes, check fasting glucose before and during use.
Work out the units to draw with the reconstitution calculator and how long a vial lasts with the vial duration calculator.
How MK-677 works
MK-677 activates the ghrelin receptor (GHS-R1a), which triggers growth hormone pulses from the pituitary — the same receptor as injectable ipamorelin, but MK-677 works by mouth. In a trial in healthy adults aged 60–81, 25 mg daily raised GH and IGF-1 into the range seen in young adults.
Trade-offs: because it mimics ghrelin (the hunger hormone), MK-677 increases appetite; in that trial, the appetite increase faded over a few months. It also caused mild, transient leg swelling and muscle pain, weight gain (2.7 kg vs 0.8 kg on placebo in the first year), a small rise in fasting blood sugar, lower insulin sensitivity and a small rise in cortisol.
Sleep: in a small study (8 young and 6 older adults), 25 mg at bedtime increased deep (stage IV) sleep by about 50% and REM sleep by more than 20% in the young adults, and REM sleep by nearly 50% in the older adults.
Over a year, MK-677 increased lean (fat-free) mass by about 1 kg but did not improve strength or function. In the DoseCraft framework it is filed under ATP Shortage (sleep and IGF-1) and, indirectly, Inflammation (sleep quality).
Safety + side-effect profile
Known effects come from human trials of up to 2 years at 25 mg a day. The appetite increase and fluid retention are the most common reasons people stop.
Blood sugar: fasting glucose rose and insulin sensitivity fell in trials. Avoid, or get medical advice first, with: diabetes or prediabetes, heart failure (fluid retention can worsen it), active cancer (GH and IGF-1 promote cell growth), pregnancy, breastfeeding.
Interaction notes: don't combine with other GH secretagogues (CJC-1295 + Ipamorelin, sermorelin, tesamorelin) without medical supervision. If you take diabetes medicines, blood sugar needs monitoring and doses may need adjusting.
- • Increased appetite (in a trial, it faded over a few months)
- • Fluid retention and mild leg or ankle swelling
- • Muscle aches
- • Higher fasting blood sugar
- • Deeper sleep and vivid dreams
- • Small rise in cortisol
Frequently asked
What is MK-677?
MK-677 (ibutamoren) is an oral ghrelin-receptor agonist originally developed by Merck. It raises growth hormone and IGF-1 and has been tested in human trials, but it is not approved for any use. It is usually taken once daily, often at bedtime.
What is the typical MK-677 dose?
Most protocols use 10–25 mg by mouth once daily, usually at bedtime. Human trials used 25 mg once daily. Starting at 10 mg and increasing only if appetite, swelling and blood sugar stay manageable is common.
MK-677 vs CJC-1295 + Ipamorelin — which is better?
MK-677 is oral and has human trials of up to 2 years; in those trials it increased appetite and raised blood sugar and cortisol. CJC-1295 + Ipamorelin is injected and has little human data; ipamorelin did not raise cortisol in animal studies. Neither is approved for body composition or anti-aging.
How much weight will I gain on MK-677 from water retention?
In the 2-year trial in older adults, people on 25 mg gained about 2.7 kg in the first year (vs 0.8 kg on placebo). That gain was a mix of lean mass and some limb fat, alongside fluid retention; mild leg swelling was common and transient.
Does MK-677 cause permanent insulin resistance?
There's no evidence it's permanent, but what happens after stopping isn't well studied. In trials, fasting glucose rose (by about 5 mg/dL on average) and insulin sensitivity fell while people took it. If you have diabetes or prediabetes, avoid it or use it only with medical supervision, and check fasting glucose before and during use.
How long until I see results?
In trials, GH and IGF-1 rose with daily dosing, and lean mass increased by about 1 kg over a year without better strength or function. Sleep changes were measured after 1–2 weeks in a small study. IGF-1 is usually rechecked after 4–6 weeks.
Should I cycle MK-677?
There's no trial evidence on cycling — the 2-year trial dosed continuously. The common convention is 8–12 weeks on, 4 weeks off, mainly to limit effects on appetite and blood sugar.
Are there long-term safety concerns?
The longest trial ran 2 years in healthy older adults and reported no serious adverse effects, but fasting glucose and cortisol rose, insulin sensitivity fell, and increased appetite, swelling and muscle pain were common. Effects beyond 2 years, and in younger users, are unknown.
Related compounds
Often researched, stacked, or compared with MK-677.
Cited research
Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med, 2008.
Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology, 2008.
Page updated · How we grade evidence
Build your MK-677 protocol with Coach
Coach personalizes the dose, stack, and cycle for your specific goals — and saves the result as a cited PDF you can bring to your doctor. Free for 14 days.
Start 14-Day Free TrialNo credit card · cancel anytime