All compounds

MK-677

Also sold as ibutamoren, ibutamoren mesylate, MK-0677, nutrobal. Orally active growth hormone secretagogue (ghrelin receptor agonist).

Works as advertised, real trade-offs (2 of 5)

MK-677 is unusual on this site: it was studied properly in humans for two years, it did increase lean mass, and the same trial found it raised blood glucose and worsened insulin sensitivity without improving strength or function.

What it is

MK-677, sold as ibutamoren, is an orally active growth hormone secretagogue developed by Merck. It mimics ghrelin — the hormone that signals hunger — at the receptor that also triggers growth hormone release.

The clinical ambition was reasonable: growth hormone declines with age, injectable growth hormone is expensive and awkward, and a pill that raised your own production could plausibly help with age-related muscle loss, frailty and bone density.

It was tested seriously. Merck ran real trials, including a two-year randomised controlled trial in healthy older adults, and trials in Alzheimer’s disease, sleep and bone metabolism. It was never approved, and the trials are the reason why — not because they were never done, but because of what they found.

MK-677 is not a SARM and does not touch the androgen receptor. It is grouped with SARMs by the shops that sell it and by almost everyone who discusses it, and that grouping is wrong in a way that matters: MK-677 does not suppress your testosterone, and the risk you are accepting is entirely different.

It is also the compound on this site, apart from creatine, where you can actually look up what happened when people took it for a long time.

What it actually does

Two effects, and both are pronounced.

It raises growth hormone and IGF-1. Not by adding external hormone but by prompting your own pituitary to release more, and unlike injected growth hormone it preserves the natural pulsing pattern. IGF-1 rises substantially and stays raised.

It makes you extremely hungry. This is not a side effect — it is the same receptor doing the same job. MK-677 is a ghrelin mimetic, and ghrelin’s day job is hunger. People describe an appetite that is genuinely difficult to manage.

The downstream effects people notice: weight goes up, some of it lean mass and a lot of it water, particularly early. Sleep quality improves, which is a real finding with trial evidence behind it and is the effect many long-term users say they value most. Skin, hair and nails often improve.

Two things it is widely believed to do that the trials did not find: make you stronger, and make you better at things. Hold onto that distinction.

What the evidence actually shows

This is the most substantial human evidence base of anything on this site other than creatine, and it is unusually informative because the trial that matters ran for two years.

The two-year randomised trial in healthy older adults found that MK-677 raised growth hormone and IGF-1 to the levels of much younger adults, and increased lean body mass. That is the headline the marketing uses, and it is true.

The rest of the same trial is the part that does not get quoted. The increase in lean mass did not translate into increased strength or improved physical function. And MK-677 increased fasting blood glucose and reduced insulin sensitivity. Some participants developed changes consistent with prediabetes. There was also fluid retention, and some participants experienced heart failure symptoms — in an older population, but worth knowing.

The Alzheimer’s trial found no effect on disease progression. The sleep work found genuine improvement in sleep quality, which is the most solidly supported benefit here. The bone trials found increased bone turnover markers, and combining it with alendronate in postmenopausal osteoporosis did not deliver the outcome that would have made it a bone drug.⁵

What that adds up to: MK-677 does exactly what it says to your hormone levels and your body composition, and the clinical benefits that were supposed to follow did not materialise, while a measurable metabolic cost did. That is not a compound that failed to work. It is a compound that worked and turned out not to be worth it for the indication it was aimed at.

The unresolved question is IGF-1 and cancer. IGF-1 is a growth signal, and higher circulating IGF-1 is associated in epidemiology with higher risk of some cancers. Nobody has shown that raising IGF-1 with MK-677 causes cancer, and we are not going to imply that they have. But raising a growth signal substantially, for years, in a healthy person, is a decision made without data. That is a real gap, not a rhetorical one.

Most trial participants were older adults. Almost nobody taking MK-677 today resembles them.

The risk profile

Works as advertised, real trade-offs (2 of 5) — It does the thing people take it for, and it costs something specific and known.

What going wrong looks like from the inside

The thing that will actually bother you and the thing that actually matters are different, and that gap is the trap.

What you will notice is hunger and water. The appetite is not subtle — people describe waking in the night to eat, and finding that their usual discipline simply stops working. Combined with fluid retention, the number on the scale rises quickly, and it is easy to read that as the compound working. Some of it is muscle. A good deal of it is water, and it goes when you stop. Puffiness in the face and hands, and stiff or tingling fingers in the morning, are the common complaints.

What matters is the thing you cannot feel. Rising fasting glucose and falling insulin sensitivity produce no sensation. There is no symptom until there is a diagnosis. In a two-year trial in supervised participants this was measured; in you, taking it from a website, it is measured only if you go and get it measured.

That risk is not evenly distributed, and this is the practical point of this page. If you are lean, young and metabolically healthy, a modest shift in insulin sensitivity is probably absorbed without consequence. If you are carrying extra weight, have a family history of type 2 diabetes, have had gestational diabetes, or are already prediabetic, MK-677 is pushing on precisely the thing that is already under strain — and the appetite effect makes you eat more at the same time. That combination is how someone crosses a line they did not know they were near.

The one thing to actually do: get fasting glucose and HbA1c checked before starting and again a few months in. It is a routine, cheap blood test that any doctor will order, and it converts the invisible risk into a number you can see. Almost nobody does this.

The other honest note: lethargy. A significant number of people find MK-677 makes them tired and heavy-feeling during the day, despite the better sleep. If that happens, it is common and it is a reasonable reason to stop.

Interactions and combinations

MK-677 is not a central nervous system depressant, and the combination risk that dominates the phenibut, kratom and tianeptine pages does not apply.

The interaction that matters is anything affecting blood sugar. If you take metformin, insulin or any other diabetes medication, MK-677 works against it and this needs a prescriber’s input, not a forum’s. If you are on a corticosteroid, which also raises blood glucose, the two together push harder in the same direction.

It is routinely stacked with SARMs, and the stacking is worth separating out mentally. SARMs bring liver risk and testosterone suppression; MK-677 brings neither. MK-677 brings glucose and IGF-1 questions; SARMs do not. Assuming one page’s risks apply to the other compound is the standard error.

If you have active cancer or a history of it, the IGF-1 question stops being theoretical enough to wave away, and this is a conversation for an oncologist.

MK-677 is prohibited in tested sport and is detectable.

If you’re already using it

There is no withdrawal. Stopping is straightforward, and most of the water weight and the appetite go with it — as, in time, do the lean-mass gains, which were partly dependent on the compound.

Get fasting glucose and HbA1c checked. This is the single useful action on this page, it is cheap, and it turns the one risk you cannot feel into information. If either has moved meaningfully, that is a reason to stop and a reason to talk to a doctor, not a reason to push through.

If you notice the classic signs of high blood sugar — unusual thirst, urinating far more than normal, blurred vision, wounds healing slowly — stop and get tested promptly.

Do not fight the appetite with stimulants. That is a common approach and it swaps a metabolic problem for a cardiovascular one.

Tell your doctor what you took by name. “MK-677, ibutamoren — a growth hormone secretagogue, a ghrelin receptor agonist” is the phrase that gets understood. It matters most if you are ever investigated for a glucose abnormality, because this is a genuine and reversible cause that nobody will otherwise think of.

This page has not yet been reviewed by a clinician. It was written from the published literature and every claim is cited, but no named medical professional has checked it. We say so here rather than let a missing byline read as an implicit one.

Last reviewed 7 September 2026. Found something wrong? Corrections are published, not silently edited.