MK-677 (Ibutamoren)
The oral growth hormone secretagogue that tricks your body into producing more GH — no needles required.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
10 – 25 mg
10 mg
2-4 weeks initial
25 mg
Studied up to 1-2 years
Compound profile
Scientific & efficacy data
Growth Hormone
Peptide profile
Moderate human trials
MK-677 (Ibutamoren)
10 mg · Once daily
Molecular formula
C27H36N4O5S
- Mol. weight
- 528.7 g/mol
- CAS number
- 159634-47-6
- PubChem
- 178024
- Developed · 1995
- Merck Research Laboratories
Merck & Co.
Amino acid sequence
N/A — Non-peptide small molecule (spiroindoline growth hormone secretagogue)Muscle and body composition
MK-677 effectively builds lean muscle mass and improves body composition in clinical trials. [1][8] Users gain 1-2 kg of lean mass over 8-12 weeks while losing fat, making it excellent for recomposition goals.
Recovery and athletic performance
Growth hormone elevation significantly accelerates muscle recovery, reduces soreness, and improves athletic performance. These benefits compound over weeks, making training more sustainable.
Sleep quality and metabolic health
MK-677 deepens sleep architecture and enhances sleep quality, [6] supporting better recovery and metabolic function. Improvements in insulin sensitivity, LDL cholesterol, and overall energy are documented in clinical research.
Dosing
How much do I take?
10 mg, titrated to 25 mg · once daily
10 – 25 mg
Once daily
Covers all 2 documented dose levels · timing · dose-adjustment guidance.
Suitability
Is this right for me?
Best for building lean muscle mass and strength & improving overall body composition in aging adults
Best for
Older Adults (60+) Seeking Body Composition Improvements
MK-677 was designed for aging populations. It restores GH and IGF-1 to youthful levels, [7] increases lean mass, and improves physical function in people over 60. A 2-year clinical trial showed a 1.1 kg gain in fat-free mass [1] with only modest fat gain—ideal for maintaining strength in older age.
Athletes and Fitness Enthusiasts Wanting Recovery Support
Oral dosing makes MK-677 convenient for athletes. It enhances muscle protein synthesis, speeds recovery after intense training, and supports lean mass building without the hassle of injections.
People with Chronic Wasting or Protein Deficiency
Clinical trials show MK-677 helps treat protein-energy wasting in kidney disease and other conditions. [2] It stimulates appetite (a feature in these populations) and preserves muscle tissue—making it useful for those losing mass despite good nutrition.
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare MK-677 (Ibutamoren) with similar peptides to find the best fit for your goals.
Administration
How do I use it?
Oral (capsule or liquid)
Route
Oral administration — no injection required. Simply swallow the capsule with water or measure the liquid dose with a dropper.
Best sites
Covers step-by-step technique · storage · a sample daily schedule.
Safety
Is it safe?
3 common side effects · 1 serious
MK-677 has been studied in hundreds of humans over 2+ years and is generally well tolerated.
[1][3] Most side effects are mild and manageable, especially with lower starting doses. The lack of injection requirement makes it safer than injectable GH in terms of infection risk and sterility concerns. However, it is not FDA approved and should be viewed as a research compound.
Common side effects · experienced by some users
Increased appetite
Most users experience heightened hunger within the first 1-2 weeks. Appetite typically normalizes after 4-6 weeks as the body adapts. This occurs because MK-677 stimulates ghrelin signaling [1][5].
Management: Eat protein-rich meals to feel fuller longer. Stay hydrated. Consider taking MK-677 in the morning to manage hunger throughout the day. This side effect can be leveraged if you're trying to gain muscle.
Mild water retention or edema
Slight puffiness in hands, feet, or face may appear in weeks 2-4. This is usually mild and resolves with continued use. Related to increased IGF-1 and growth signaling [1].
Management: Increase potassium intake (bananas, sweet potatoes). Reduce sodium if bloating is bothersome. Compression socks may help with ankle swelling. Mild edema is not dangerous but can be uncomfortable.
Elevated fasting glucose
Fasting blood sugar may increase by 5-15 mg/dL, reflecting mild insulin resistance that typically develops with GH elevation. This is reversible and usually mild in healthy individuals [1][7].
Management: Monitor fasting glucose every 4 weeks. Maintain regular exercise and limit refined carbohydrates. If glucose rises > 30 mg/dL or exceeds 130 mg/dL, discontinue and consult a doctor.
Less common
These typically resolve with continued use or dose adjustment.
Stop and seek help if
- Fasting glucose becomes elevated and uncontrollable (> 130 mg/dL despite diet changes)
- Severe allergic reaction such as itching, swelling, or breathing difficulty
- Joint pain or carpal tunnel symptoms worsen and persist beyond 3 weeks
- Blood pressure elevation becomes problematic (systolic > 150 mmHg)
- Suspicion of liver or kidney dysfunction (yellowing of skin, dark urine)
- Planned surgery or medical procedure (discontinue 2 weeks before)
This list is for informational purposes and does not replace medical advice. Stop use and consult a healthcare provider immediately if you experience any concerning symptoms. Individual responses vary, and a doctor can help determine if MK-677 is appropriate for your health profile.
With other peptides
- Safe:Sermorelin or GH-releasing peptides (GHRP-6, GHRP-2) — Synergistic effect — both stimulate GH release. Stacking may amplify GH and IGF-1 elevation but increases side effect risk.
- Safe:Testosterone or SARMs — Complementary anabolic effects. MK-677 enhances protein synthesis; testosterone boosts muscle growth. Combination is effective but requires monitoring.
With medications
- Caution:Insulin or insulin secretagogues (metformin, sulfonylureas) — Risk of hypoglycemia. MK-677 raises blood glucose; combining with insulin-lowering drugs can cause dangerously low blood sugar.
- Safe:Thyroid medications (levothyroxine) — MK-677 may increase metabolic rate slightly. Thyroid dose may need adjustment. Monitor TSH every 4-6 weeks.
- Safe:Blood pressure medications — MK-677 may mildly elevate blood pressure. ACE inhibitors or ARBs may need dose adjustment. Monitor BP regularly.
- Safe:Estrogen or hormonal birth control — Theoretical risk of interaction via hormone signaling. Use with medical supervision if taking hormonal medications.
With supplements
- Safe:Creatine monohydrate — Synergistic for muscle gains. No safety concerns. Combination is common among athletes.
- Safe:Whey protein or BCAAs — Complementary for muscle protein synthesis. MK-677 boosts anabolism; protein provides building blocks. Safe and synergistic.
- Safe:Melatonin or sleep supplements — MK-677 enhances sleep; melatonin adds to this. Safe combination for better recovery. No contraindications.
Effectiveness
How do I know it's working?
Moderate human trials · first signs week 1-2
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
Research compound
Onset of effects
Moderate
(1-2 weeks)
How it works
MK-677 is a small molecule—not a peptide—that tricks your body into releasing more growth hormone.
It binds to ghrelin receptors in your brain, mimicking the hunger hormone ghrelin. This triggers your pituitary gland to release more GH, which then stimulates your liver to produce IGF-1, a powerful growth factor.
Unlike injected growth hormone, MK-677 works by sending a signal to your body's own GH factory, making the process feel more natural. The best part: you just swallow a capsule once a day [5][7].
The deeper mechanism
MK-677 is a selective, non-peptide ghrelin receptor (GHSR) agonist with a spiroindoline core structure. [5] It crosses the blood-brain barrier and binds to growth hormone secretagogue receptors on arcuate nucleus neurons with nanomolar affinity (IC50 ~1.3 nM).
[5] This receptor activation depolarizes neurons and increases GnRH and neuropeptide Y signaling, which stimulates GH-releasing hormone (GHRH) release from the hypothalamus. Elevated GHRH then stimulates somatotroph cells in the anterior pituitary to pulse GH secretion.
MK-677 amplifies both the baseline GH secretion and the amplitude of GH pulses [7] without suppressing somatostatin, allowing sustained elevation. Elevated GH acts on hepatocytes to increase IGF-1 production via JAK2-STAT5 signaling.
IGF-1 then activates mTOR and PI3K pathways in muscle tissue, promoting protein synthesis, hypertrophy, and anti-catabolic effects. The half-life of MK-677 is 4-6 hours, but IGF-1 elevation persists ~24 hours due to IGF-1's longer half-life (15-20 hours), permitting once-daily dosing.
MK-677 also has mild appetite-stimulating effects independent of GH, likely through direct hypothalamic ghrelin receptor signaling.
What to expect
Week 1-2
What you might notice
- Increased appetite (the most common early sign)
- Slightly better sleep quality
- Mild energy boost or fatigue (varies)
What's normal
- Appetite increase is expected and normal — it means MK-677 is working
- Mild water retention may start appearing
- No dramatic changes in strength or body composition yet
What's next
- Blood tests will show elevated IGF-1 levels (confirm efficacy)
- GH pulses increase but remain below peak levels
- Continue consistent dosing; effects compound over weeks
Week 3-4
What you might notice
- Improved recovery after workouts
- Appetite normalizing or becoming manageable
- More defined muscle pumps during training
- Noticeably better sleep architecture
What's normal
- Joint aches may appear (growth signaling outpacing adaptation)
- Mild carpal tunnel symptoms in some users
- Slight increase in body weight (mostly water and muscle)
What's next
- Switch from starting dose to standard dose if tolerating well
- Body composition changes begin (lean mass > fat gain)
- Second blood test often shows stronger IGF-1 elevation
Week 5-8
What you might notice
- Visible increase in muscle definition and fullness
- Reduced body fat percentage (if diet is dialed in)
- Measurable strength gains in major lifts
- Improved athletic performance and endurance
- Consistently better sleep and mood
What's normal
- Fasting glucose may be elevated but typically mild
- Joint pain usually resolves by now
- Water retention stabilizes at a low level
- Appetite levels out to a new baseline
What's next
- Peak IGF-1 elevation is established
- Continued lean mass gains and fat loss acceleration
- Third blood test confirms sustained elevation
Week 9-12
What you might notice
- Marked improvements in body composition
- Peak muscle hardness and vascularity
- Strength levels at or near cycle peak
- Excellent recovery even from high training volume
- Stable, elevated baseline energy
What's normal
- Side effects remain minimal or absent
- Fasting glucose plateau (important to monitor)
- Body adapted to appetite stimulation
- Sleep quality remains enhanced
What's next
- Consider cycle completion or continuation based on goals
- If extending cycle, take a 4-6 week break before restarting
- Final blood work confirms efficacy and safety profile
Signs it's working
Laboratory markers
- Serum IGF-1 elevation of 50-100% above baseline (measured via blood test)
- Growth hormone pulse frequency and amplitude increase on 24-hour GH testing
- Fasting glucose modest increase (typically 5-15 mg/dL, reversible)
Physical and performance improvements
- Lean muscle mass gain of 1-2 kg over 8-12 weeks
- Measurable strength increases in major lifts (5-15% improvement)
- Improved muscle recovery and reduced soreness after training
- Body fat loss or body recomposition favoring muscle over fat
Quality of life markers
- Improved sleep quality and deeper restorative sleep
- Increased energy and overall sense of well-being
- Enhanced appetite (useful for those needing to gain mass)
- Improved mood and cognitive function
Not seeing results? Common reasons
- Dose too low: Starting at 10 mg may show muted results. If no improvements by week 4, consider increasing to 25 mg.
- Inconsistent timing: Varying dose times by hours disrupts GH pulse patterns. Lock in a consistent daily time to maximize effect.
- Poor diet or inadequate protein: MK-677 boosts growth signals, but muscle synthesis requires protein. Ensure 1-1.2g protein per pound of body weight.
- Insufficient sleep: MK-677 enhances sleep, but you must provide adequate sleep duration (7-9 hours). Poor sleep blunts gains.
- High stress or cortisol: Stress hormone cortisol opposes growth signaling. Manage stress with exercise, meditation, or other techniques.
- Underlying metabolic issues: Uncontrolled diabetes, thyroid dysfunction, or severe metabolic syndrome can blunt MK-677 effectiveness. Get bloodwork done.
Key research
Questions
Frequently asked
Is MK-677 a peptide?
No. MK-677 is a small-molecule peptidomimetic—it mimics what a peptide does without being one. It's a spiroindoline compound that activates ghrelin receptors. [5] The key advantage: it's orally active (swallow a capsule), whereas real ghrelin peptides would be destroyed by stomach acid and require injection.
How quickly does MK-677 work?
IGF-1 and growth hormone start rising within hours of the first dose, [8] but noticeable changes in muscle, strength, and body composition take 3-4 weeks. The biggest improvements appear by week 8-12. Patience is key—this is not an overnight transformation.
Do I need to inject MK-677?
No injections required. MK-677 is taken orally as a capsule or liquid suspension. You simply swallow it once daily with water. [7] This is one of its greatest advantages—convenience and no injection-related risks like infection or abscesses.
Will MK-677 raise my blood sugar?
Can I stack MK-677 with testosterone or other compounds?
Yes. MK-677 pairs well with testosterone, SARMs, or other growth-promoting compounds. The combination is synergistic for muscle building. However, stacking increases monitoring requirements (more bloodwork, more side effect risk). Stack only if you have experience and access to bloodwork.
Is MK-677 legal?
MK-677 is not FDA approved and is classified as an investigational new drug. It is legal to possess in the United States for research purposes but illegal to sell as a dietary supplement or for human consumption. It exists in a gray legal area. Research local and national regulations before purchasing.
How long should I cycle MK-677?
Typical cycles are 8-12 weeks. Some users extend to 16 weeks without major issues. After a cycle, take a 4-6 week break to allow your natural GH/IGF-1 to normalize. This prevents downregulation of receptors and maintains long-term effectiveness.
Further reading
History & related research
History · since 1997
The Pill That Acts Like a Peptide
MK-677 is not a peptide — it's a small molecule that tricks your body into releasing growth hormone like a peptide would. Developed in Merck's labs in the mid-1990s, it was the first oral compound ever made to hit the ghrelin sensor (the hunger hormone receptor).
Read the full history of MK-677 (Ibutamoren)Ready for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for MK-677 (Ibutamoren), on one page.