MK-677
Ibutamoren
MK-677 (Ibutamoren) is an orally active growth-hormone secretagogue — a non-peptide molecule that raises growth hormone and IGF-1 with a single daily capsule, no injections required. That convenience, plus a long half-life and durable effect, is why it's one of the most popular compounds in the GH-support world. This guide covers how MK-677 works, what the research shows, dosing references, its real side effects, and legal status.
MK-677 quick facts
| Reported research dosing | 10mg-25mg |
| Route | Oral |
| Cycle length | 3-6 Months |
| Frequency | 1x Daily Anytime |
| Half-life | ~24 hrs |
| Forms | Oral |
| Evidence level | Human trials |
Oral convenience, but it drives appetite and water — respect that. Not for everyone.
How MK-677 works
MK-677 is an oral ghrelin-receptor (GHSR-1a) agonist — it mimics the hunger hormone ghrelin to stimulate a pulsatile release of growth hormone and sustain elevated IGF-1 for up to 24 hours. Like the injectable secretagogues, it works with your own axis: GH release still responds to GHRH and somatostatin, so it raises the baseline without shutting your system down the way exogenous HGH does. Its big practical advantage is being oral and long-acting — one daily dose vs multiple injections.
What the research shows
Across human studies, MK-677 has reliably raised GH and IGF-1 without meaningfully raising cortisol. The standout is the Nass et al. 2-year trial, which showed MK-677 maintained its GH-elevating effect over extended use without tolerance — an important finding, since many GH-boosting approaches fade. Research interest spans body composition, bone density, sleep quality and recovery. Note: despite this, MK-677 failed to gain approval for its originally-studied indications, so it remains a research compound.
MK-677 dosing (research reference)
Because of its ~24-hour half-life, the literature references a single daily oral dose as sufficient to keep GH and IGF-1 elevated — a key contrast with short-acting injectable secretagogues that need multiple daily shots. It's oral, so there's no reconstitution involved. This summarizes existing references for education only and is not dosing advice or a recommendation for human use.
Side effects — the honest picture
MK-677 has a few characteristic effects worth knowing. Because it activates the ghrelin receptor, it increases appetite — often the first sign it's 'working,' but a real consideration if you're in a cut. It commonly causes fluid retention, especially in the first 4–6 weeks. And most importantly, it can raise fasting blood sugar and insulin and cause mild insulin resistance in some people — so blood-sugar monitoring is genuinely important, particularly for anyone with metabolic risk factors.
Related compounds & comparisons
MK-677 targets the same GH axis as the injectable secretagogues but from a different angle. Ipamorelin and other GHRPs give sharper, shorter pulses via injection and don't raise appetite the way MK-677 does; CJC-1295 is a GHRH often stacked with those. MK-677's trade-off is oral convenience and a sustained IGF-1 elevation vs more appetite, fluid retention and blood-sugar considerations.
Legal & regulatory status
MK-677 is not FDA-approved for any indication and is sold as a research compound (research use only). It is also banned in competitive sport under WADA. Its status, like other GH-axis compounds, is subject to ongoing regulatory attention. Follow the laws and sport rules that apply to you.
Where to get MK-677
Buy MK-677 at Soma Chems →The evidence for MK-677
Graded by what exists behind each claim.
✅ Clinically validated
- Real human trials, and they are the reason to be careful rather than excited. A two-year randomized trial in healthy older adults raised IGF-1 to young-adult levels and increased fat-free mass by roughly 1.6 kg — the efficacy signal is not in doubt. The same program showed increased fasting glucose and reduced insulin sensitivity.
- Development for frailty was discontinued and a hip-fracture trial stopped early. That is a different kind of failure from a compound that does nothing — it worked, and the metabolic cost was judged not worth it for a frail elderly population on a long-term daily drug. Someone using it in short courses with normal glucose handling is not that population, which is the honest read and also not a license to ignore the finding.
📊 Correlative data
- Very widely used, and the reported experience matches the trials closely: marked appetite increase, water retention and improved sleep depth within days, lethargy and puffiness in a substantial minority.
- Because it is orally active and long-acting, people run it for months, which is precisely the pattern the glucose data argues against.
🧪 Theoretical / extrapolated
- An orally-bioavailable ghrelin-receptor agonist with a ~24-hour half-life. Continuous receptor occupancy is the key mechanistic difference from injectable secretagogues — it produces a sustained elevation rather than a pulse, and sustained GH/IGF-1 signaling is what predicts the insulin resistance the trials found.
- The same continuous ghrelin signaling predicts the appetite effect, which is a feature if you are trying to gain and a serious problem if you are not.
How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →
What MK-677 actually does
MK-677 is not growth hormone and it is not a growth hormone releasing hormone analog. It is a non-peptide agonist at the receptor for a stomach hormone, and every distinctive property of the compound — the oral activity, the 24-hour half-life, the hunger, the fluid retention — follows from that one fact.
The receptor. A receptor in pituitary and hypothalamus that functions in growth hormone release was cloned before its natural ligand was known Howard 1996; three years later that ligand was identified as ghrelin, an acylated peptide from the stomach Kojima 1999. The receptor is GHS-R1a. Unlike the GHRH receptor, which couples to Gs and cAMP, GHS-R1a couples to Gq/11: phospholipase C, inositol trisphosphate, intracellular calcium release. Two different receptors, two different second messengers, one hormone released — which is why a secretagogue and a GHRH analog are synergistic rather than redundant.
How the ligand actually sits in the pocket. A cryo-electron microscopy study resolved the structural basis of human ghrelin receptor signaling by ghrelin and by the synthetic agonist ibutamoren Liu 2021. That is unusually good structural evidence for anything in this Vault: the binding mode of the exact molecule sold as MK-677, in the exact human receptor, resolved rather than modeled.
The property of this receptor that almost nothing else shares. GHS-R1a has very high constitutive activity — it signals with no ligand bound at all — and the endogenous peptide LEAP2 is an antagonist and inverse agonist of it Ge 2018. So the physiological system is not off-until-ghrelin-arrives; it is a tone set by the ratio of two opposing peptides. An exogenous agonist does not switch a system on. It shifts a balance, against an inverse agonist whose concentration changes with nutritional state and which nobody using this compound measures.
What the pituitary then does, and why it matters that it is the pituitary. GHS-R1a agonism amplifies endogenous growth hormone pulses. Because the release is still pituitary, it remains subject to somatostatin and to IGF-1 negative feedback — a ceiling that injected growth hormone bypasses entirely Colldén 2017. That ceiling is the strongest argument for a secretagogue over exogenous GH, and it is also the reason the effect size is smaller.
And the effects that are not growth hormone at all. The ghrelin receptor is expressed in the gut, the pancreas and the cardiovascular system as well as the pituitary Colldén 2017. Appetite stimulation, the fall in insulin sensitivity and the fluid retention are receptor pharmacology at those sites, not side effects of the growth hormone.
Cell, rodent, human — and where it stops
Step one, receptor and structure: settled, and better resolved than most. Receptor cloning Howard 1996, endogenous ligand Kojima 1999, endogenous inverse agonist Ge 2018 and the cryo-EM structure with ibutamoren bound Liu 2021.
Step two, humans, and the trial everybody quotes. Nass 2008 tested an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults and was published in Annals of Internal Medicine — a randomized trial of the actual molecule in the actual population, which is a stronger starting point than most compounds here have. Read what it measured: body composition and clinical outcomes, in older adults, over a defined period. It is not a trial in trained young men and it did not measure strength gains in a gym.
Step three, the therapeutic program, and the honest summary of it. The ghrelin pathway has been reviewed as a therapeutic target across cachexia, sarcopenia and gastrointestinal indications Colldén 2017. MK-677 has been in human trials since the 1990s and has never been approved for any indication anywhere. That is not a conspiracy; it is a statement about the ratio of the effect to the metabolic cost across every program that ran it.
Step four, the adverse-event side, which is a real report and not a theoretical concern. Acute pancreatitis related to a ghrelin receptor agonist has been published Iwai 2022. One case report is one case report — but it is a case report about an organ where the receptor is expressed, which is the difference between a signal and a coincidence.
Where the chain breaks. (1) The pivotal human data is in healthy older adults Nass 2008; the users are mostly young and training, and in that group the endogenous growth hormone pulse is already large, so the headroom a secretagogue can add is smaller. (2) The IGF-1 feedback ceiling means the dose-response flattens, and no trial has mapped where. (3) LEAP2 varies with nutritional state Ge 2018 and is never measured, so identical doses produce different receptor occupancy in different people and in the same person at different times. (4) The insulin-sensitivity cost is a consistent finding across the literature and is the reason the programs stopped, so any personal-use argument has to account for it rather than treat it as an anecdote.
What would have to be true, and how you would know it was not
Three predictions. The first proves the compound is real, the second is the ceiling, and the third is the cost.
1. If GHS-R1a is being occupied, IGF-1 rises and it rises within weeks. IGF-1 is the correct read-out rather than growth hormone, and the reason is mechanical: GH is secreted in pulses and a random daytime GH level is close to meaningless, while IGF-1 is liver-derived, largely protein-bound and stable through the day. Measure IGF-1 at baseline and at 6 weeks. If it has not moved, the compound is not being absorbed, is not what it claims to be, or the dose is below threshold — and no amount of improved sleep quality is evidence against that.
2. The ceiling prediction, which is the one that argues against dose escalation. Pituitary release remains under IGF-1 and somatostatin negative feedback Colldén 2017. So IGF-1 should rise and then plateau, and a higher dose past the plateau should add adverse effects without adding IGF-1. Two IGF-1 measurements at two doses is a within-person dose-response, and it is the single most informative experiment a user can run on themselves.
3. The prediction that cuts against the compound, and it is not subtle. Ghrelin receptor agonism reduces insulin sensitivity. Fasting insulin and HbA1c at baseline and at 12 weeks, with a CMP for fasting glucose. If fasting insulin climbs while IGF-1 climbs, the compound is working exactly as its pharmacology predicts and the trade is visible. A person who measures only IGF-1 will see one half of that trade and conclude the compound is free.
What will fool you. Weight gain in the first fortnight is mostly water — fluid retention is a documented effect and it reads on a scale as progress. A CMP showing a fall in sodium, or ring and shoe tightness, is the better interpretation.
What nobody has tested yet
Four experiments nobody has run.
Nobody has measured LEAP2 in anyone taking MK-677. The endogenous inverse agonist sets the receptor's basal tone Ge 2018, varies with nutritional state, and is never measured. If responders and non-responders differ in LEAP2, that single assay would explain the most consistent complaint about this compound — that it works dramatically for some people and does nothing for others.
Nobody has run a trial in trained young adults. The human evidence is in healthy older adults Nass 2008. The population using it has a different baseline growth hormone axis, and nobody has measured whether the effect survives that difference.
Nobody has tested whether the insulin cost is reversible or cumulative. The falling insulin sensitivity is consistently reported; whether it fully reverses on discontinuation, and whether repeated cycles leave a residue, has never been measured with an oral glucose tolerance test before, during and three months after.
Nobody has separated the sleep effect from the growth hormone effect. Slow-wave sleep and the largest natural growth hormone pulse coincide, and users consistently report deeper sleep. Whether MK-677 improves sleep architecture directly, or whether better sleep is what raises IGF-1, is a question a polysomnograph with overnight growth hormone sampling would answer in one night. The causal direction here has never been established, and it determines whether the compound is a growth hormone drug with a sleep side effect or a sleep drug with a growth hormone consequence.
MK-677 — its own safety story, not its class's
MK-677 has never been approved for any indication anywhere, despite thirty years of clinical development by a major pharmaceutical company. That is the single most informative safety fact on this page and the class block above does not contain it.
The metabolic cost is the reason. Ghrelin receptor agonism lowers insulin sensitivity and raises fasting glucose. In a healthy person that may be a tolerable and reversible shift; in somebody with prediabetes it is the drug pushing in the direction the condition is already going. This is not an idiosyncratic reaction. It is receptor pharmacology at the pancreatic and hepatic ghrelin receptors Colldén 2017, and it will happen in anybody who takes an effective dose.
Fluid retention and its consequences. Raised growth hormone and IGF-1 promote sodium and water retention. That produces peripheral edema, joint stiffness, carpal tunnel symptoms from swelling in a fixed compartment, and a rise in blood pressure. Numbness or tingling in the thumb and first two fingers on a growth hormone secretagogue is a mechanical consequence of the drug rather than a coincidence.
Appetite is the effect, not a side effect. The receptor is the ghrelin receptor Kojima 1999. A person who is surprised by hunger on a ghrelin mimetic has been given the wrong description of what they are taking.
Pancreatitis has been reported with a ghrelin receptor agonist Iwai 2022. Severe persistent upper abdominal pain radiating to the back, with nausea, is a stop-and-be-assessed event rather than a tolerance issue.
The IGF-1 question that has no answer. IGF-1 is mitogenic. Raising it chronically in somebody with an undiagnosed malignancy is a theoretical risk that no trial has been long enough or large enough to quantify. The honest statement is that it is unmeasured, not that it is absent, and it is the reason a personal or family history of cancer changes this decision.
What this page will not do. Recommend a dose. The human evidence is a trial in older adults Nass 2008, the compound is unapproved, and the insulin cost is predictable enough that anybody taking it should be measuring it.
Sources read for this page
- Colldén G, Tschöp MH, Müller TD. Therapeutic Potential of Targeting the Ghrelin Pathway. International Journal of Molecular Sciences 2017 · PMID 28398233
MK-677 — safety, predicted from mechanism
Predicted from mechanism, not from a human safety trial. How that reasoning works →
What the mechanism predicts
Derived from the molecule, not a trial.
- Everything here follows from one fact: these raise GH and therefore IGF-1. The predicted problems are the known consequences of elevated GH/IGF-1, drawn from acromegaly and clinical GH therapy where it HAS been studied — insulin resistance and rising fasting glucose, fluid retention (puffy hands and face, and the ring that stops fitting), carpal tunnel symptoms from that same fluid pressing on the median nerve, and joint aches.
- The proliferation question is the serious one. IGF-1 is a growth signal, and growth signals do not distinguish between tissue you want to grow and tissue you do not. There is no evidence these compounds cause cancer. There is also a clear mechanistic reason not to run them with an active or recent malignancy, and that reasoning does not require a trial to be sound.
What has actually been reported
- Injection-site reactions, transient flushing, tingling and head-rush on dosing — most commonly with the GHRPs, which also release cortisol and prolactin at higher doses.
- Increased hunger is near-universal with the ghrelin-mimetic ones (GHRP-6, MK-677, Hexarelin). That is the mechanism working, not a side effect — the same receptor drives GH release and appetite.
How to reduce the risk
Same mechanism as the prediction.
- Draw an IGF-1 baseline BEFORE you start. Once you are on, that number is the drug and you have permanently lost the comparison. This is the single highest-value thing on this list and it costs one blood draw.
- Watch fasting glucose and HbA1c, not the scale. Insulin resistance is the most likely thing to move and the one you cannot feel. Re-test at 8–12 weeks. If fasting glucose is climbing, that is your signal to cut the dose or come off — long before anything shows up symptomatically.
- Dose at night, on an empty stomach. GH release is pulsatile and largest during early sleep; food, and carbohydrate in particular, blunts the pulse through insulin. This is not a ritual — it is the same mechanism working with you rather than against you.
- Don't run a secretagogue through a high-carbohydrate surplus. The predicted problem is insulin resistance; adding a large carb load is pushing the same lever from the other end.
- Cycle rather than run continuously. Most of the predicted problems — fluid retention, carpal tunnel, glucose drift — are dose-and-duration dependent and reverse on cessation. Time off is the cheapest safety intervention available.
- If fluid retention is the issue, it usually resolves on a dose reduction long before it needs anything else. Reach for the dose before you reach for a diuretic.
What it does to your bloodwork
A fact about the assay.
- IGF-1 drawn on-cycle is not your baseline — it is the drug working, and it will read high. If you want a real baseline, draw before starting or after a proper washout.
- Watch fasting glucose and HbA1c, because insulin resistance is the most likely thing to move and the one you will not feel.
- GHRP-6 and Hexarelin can raise prolactin and cortisol; if you are chasing an unexplained prolactin result, this is a candidate.
What it overlaps with
- Stacking two secretagogues that work by the same route is redundancy, not synergy. A GHRH analog (CJC-1295, Sermorelin, Tesamorelin) plus a ghrelin mimetic (Ipamorelin, GHRP-2, GHRP-6) is the deliberate pairing — two different levers on the same axis. Two GHRH analogs together is paying twice for one lever.
Don't run this if
- Active or recent malignancy — the IGF-1 reasoning above.
- Diabetes or poor glycemic control, unless you are monitoring fasting glucose and HbA1c and know what you are looking at.
- Untreated diabetic retinopathy.
The honest unknown
- Nobody has run long-term studies of intermittent secretagogue use in healthy adults. The specific unmeasured thing is what years of repeatedly pushing IGF-1 above your natural set point does — not whether a single cycle is tolerable, which it evidently is.
Not medical advice. If you take prescription medication or have a diagnosed condition, check this with a pharmacist or doctor.
Fasted — and pre-bed is the best of the windows
Food is the problem here, and specifically carbohydrate and fat. Both trigger somatostatin release, and somatostatin is the brake on growth hormone — eating before the injection pharmacologically cancels it. Two clear hours either side.
Pre-bed is the strongest window because the largest natural GH pulse happens in the first hours of deep sleep, so you are stacking with it rather than asking the pituitary for something it is not primed for. Fasted pre-training is the second-best, for the same reason in a different rhythm.
From half-life and route, not a dosing trial.
MK-677 — interference & stacking
Predicted from mechanism, not from an interaction study. How mechanism-predicted claims are made →
What MK-677 moves on your bloodwork
Expected direction, not a measured one.
- IGF-1 (Insulin-like Growth Factor 1) — ↑ expected to rise
This is the point. IGF-1 rising is the compound doing its job — it is the stable downstream readout of a GH pulse.
What to do: Test it before you start and again at 6–8 weeks. It is the only number that tells you whether the product was real and the dose was enough. - Growth Hormone, Serum — ✕ unreliable here
A random GH level is close to meaningless here. GH is secreted in pulses during deep sleep and sits undetectable between them, so a daytime draw catches a trough almost every time — including when the compound is working perfectly.
What to do: Do not use GH to judge a secretagogue. Read IGF-1 instead. - Fasting Insulin — ↑ expected to rise
GH is a counter-regulatory hormone: it opposes insulin. Fasting insulin and glucose drifting up is the predicted trade-off, not a surprise.
What to do: Check fasting insulin and HbA1c at baseline and again at 8–12 weeks. This is the marker that decides whether you keep running it. - HbA1c (Hemoglobin A1c) — ↑ expected to rise
Same mechanism, longer window — a slow drift rather than a jump.
What to do: Pair it with fasting insulin; either alone can mislead. - Free T4 (Thyroxine) — ↓ expected to fall
GH accelerates the peripheral conversion of T4 to T3, so free T4 can fall while free T3 holds or rises. Read alone it looks like new hypothyroidism, and it usually isn't.
What to do: Run a full thyroid panel rather than TSH alone before concluding anything.
Everything above follows from one fact: these raise GH and therefore IGF-1. Nothing here needs a trial of the specific molecule.
Everything on this page, in an order
This one is free and stays free. What Skool adds is the rest of the shelf — 278 compounds and 371 supplements with the protocol, the stack order and the bloodwork to run beside it.
Join Skool — $10/mo →Bloodwork to run alongside MK-677
Baseline first, then again at 8–12 weeks.
| Marker | What it’s watching for |
|---|---|
| Fasting Insulin | MK-677 worsens insulin sensitivity. This is the trade, not a rumor |
| HbA1c (Hemoglobin A1c) | The three-month confirmation of that trade |
| IGF-1 (Insulin-like Growth Factor 1) | What you're dosing against |
| Comprehensive Metabolic Panel (CMP) | Fasting glucose, liver and kidney |
| Complete Blood Count (CBC) with Differential | Baseline before a compound usually run for months |
The “Running GH Peptides or MK-677” panel covers these in one order — 9 markers, $132.30 with the discount applied.
Check results you already have → · All 103 markers A–Z
MK-677 — frequently asked questions
What is MK-677 (Ibutamoren)?
MK-677 is an orally active, non-peptide growth-hormone secretagogue that mimics ghrelin to raise growth hormone and IGF-1 with a single daily capsule — no injections needed.
How does MK-677 work?
It binds the ghrelin receptor (GHSR-1a) to stimulate pulsatile GH release and sustain elevated IGF-1 for up to 24 hours, while preserving your own GH feedback axis rather than replacing it like injected HGH.
Does MK-677 build tolerance?
The 2-year Nass et al. trial found MK-677 maintained its GH-elevating effect over extended use without tolerance — a notable finding versus GH approaches that fade over time.
How is MK-677 dosed?
Its ~24-hour half-life means the literature references a single daily oral dose to keep GH and IGF-1 elevated. It's oral, so no reconstitution is needed. This is educational, not dosing advice.
What are the side effects of MK-677?
Most commonly increased appetite and fluid retention (especially the first 4–6 weeks), and — importantly — it can raise fasting blood sugar and insulin and cause mild insulin resistance in some people, so blood-sugar monitoring matters.
MK-677 vs ipamorelin — what's the difference?
MK-677 is oral, long-acting and raises appetite/IGF-1 for ~24 hours; ipamorelin is an injectable that gives sharper, cleaner GH pulses without much appetite change. Different trade-offs, same GH axis.
Is MK-677 FDA-approved?
No. MK-677 is not FDA-approved for any indication and is sold as a research compound. It's also banned in competitive sport under WADA.
References & further reading
MK-677 inside a finished plan
One arm of 2 Protocol Blueprints, free to read in full.
What MK-677 is used for
MK-677 appears under 3 goals in the goal router.
Related GH & Growth compounds
Where this goes next
MK-677 is the gh / igf-1 arm of this plan. The page above is the free breakdown of one compound; the plan it belongs to — the dosing, the order to correct things in, the week-by-week schedule and what to retest — is a lesson inside Skool.