The Beauty of Modern Science: Ibutamoren (MK-677) - Mind And Muscle

Ibutamoren aka MK-677 has been sold over the counter as a bodybuilding product, or as a research chemical for quite some time now.  SARMs are the new big thing so Mk-677 has been marketed as such, however it is in fact NOT a SARM.  SARMS are selective androgen receptor modulators, which by act they exact same way steroids do; only SARMs are selective and target only specific androgen receptors.  The good thing about SARMs is it’s like taking a mild steroid without getting side effects (immediately anyhow).  The potential side effects of SARMs are relatively unknown, although they could be quite harmless and eventually replace steroids all together.  That being said, MK-677 (Ibutamoren) does not target any androgen receptor in the human body, and is therefore not a SARM.  Simply put, it’s better than a SARM, and it’s in a complete class of it’s own.

MK-677 is an orally active, bio-available compound that exerts effects that were originally though to be completely indistinguishable from Growth Hormone Releasing Peptide (GHRP-6).  This is more commonly known as ghrelin… the hunger hormone??  Ghrelin levels do indeed spike before meals, and the effects of ghrelin and MK-677 happen to make you feel a little hungry.  This is a misnomer however, and their action targets multiple brain regions that are important for metabolic engagement.  So, as a ghrelin agonist (or GHRP-6), MK-677 activates receptors that prepare the body to nourish, grow, repair, and be active.  As well as causing a massive increase in growth hormone levels.

Growth hormone is the real worlds fountain of youth.  It makes you stronger, leaner, healthier, improves skin and hair, and possibly even smarter.  Although, growth hormone has not been studied as a cognitive enhancer in healthy adults, it is naturally highest during life periods with the highest rate of cognitive development; even more importantly it has been found to improve cognition in those with Alzheimer’s disease.  Growth hormone is undoubtedly a staple hormone in our physical development, providing the signal for our muscles to grow and proliferate; creating more muscle cells to mature and strengthen.

Muscle growth and fat loss is the main objective for the majority of people interested in MK-677.  Nice skin and hair definitely doesn’t hurt either, but the real fact here is that MK-677 is a potent growth hormone releasing compound.  It has a 24 hour half-life, making it active for long periods of time, and unlike the majority of growth hormone releasing compounds MK-677 does not increase cortisol levels.


Let’s look at the facts : Scientific Backing



Back in the day they intravenously injected MK-677 at various doses (0.01, 0.025, 0.05 and 0.1 mg/kg).  The results were quite obvious.

  • At baseline growth hormone levels were very low.
  • At very low doses the compound had no effect.
  • With an increase in dosage there is a clear dose response curve
    • Logarithmic not liner
      • Lower doses are similarly ineffective (do not reach the threshold)
      • Higher doses are similarly effective (cap out)
  • MK-677 increases growth hormone levels
    • By a nearly infinite amount technically (considering baseline was nearly zero)
    • To quantify this
      • A proper dose of MK-677 will stimulate natural growth hormone production – even with a single dose

(Smith et. al., 1995)

In another study (one without figures) healthy elderly adults were given 25 mg MK-677/day, and it was found that GH levels increased by 24% without exercising, increased even further with exercise.  The main finding was that this drug can be used in the elderly to boost GH, and that by boosting GH IGF-1 levels would increase to a healthy level for a YOUNG adult.  It was found that IGF-1 did in fact increase to levels found in young adults.  The subjects had no increase in cortisol, but their blood sugar levels did increase (because they were burning fat).

(J Clin Endocrinol Metab. 1996 Dec;81(12):4249-57.
Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects.
Chapman IM1, Bach MA, Van Cauter E, Farmer M, Krupa D, Taylor AM, Schilling LM, Cole KY, Skiles EH, Pezzoli SS, Hartman ML, Veldhuis JD,Gormley GJ, Thorner MO.)

Regardless of the reason they conducted this following study, they found that MK-677 increase the frequency of low amplitude GH pulses, not the amplitude of individual pulses.  I included this citation because there’s a limit to how hard we can push our internal organs, and the fact that MK-677 can be effective without pushing the body past it’s natural set-point is why it’s so well tolerated.

(J Clin Endocrinol Metab. 1996 Aug;81(8):2776-82.Effects of a 7-day treatment with a novel, orally active, growth hormone (GH) secretagogue, MK-677, on 24-hour GH profiles, insulin-like growth factor I, and adrenocortical function in normal young men.Copinschi G1, Van Onderbergen A, L’Hermite-Balériaux M, Mendel CM, Caufriez A, Leproult R, Bolognese JA, De Smet M, Thorner MO, Van Cauter E.)

In a clinical trial MK-677 was even able to boost growth hormone, and IGF-1 levels GH deficient children.  This is quite remarkable.  Lets put ourselves in a similar scenario; instead of being undersized children, imagine going to the doctor because you’re having difficulty having a kid.  If there was an MK-677 for that, there’d be no injections, no costly specialists, no side-effects from hormonal imbalance; just a single daily dose turns you into the guy you wish you were in high school (until he got that chick pregnant and dropped out).  Point being-all jokes aside-: MK-677 works at any age even if there’s a deficiency.
  • Literature suggests that MK-677 works even in the case of deficiencies because it works through an alternative pathway to the growth hormone releasing hormone pathway
    • Directly releasing growth hormone by intracellular signaling processes
(Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone–insulin-like growth factor I axis in growth hormone–deficient children., Murphy, 2001)

Since the past few references have been lackluster; lets take a look at this gem.

Oral Administration of Growth Hormone (GH) Releasing Peptide-Mimetic MK-677 Stimulates the GH/Insulin-Like Growth Factor-I Axis in Selected GH-Deficient Adults, 2 , , , , , , , , , , and 


  • GH was released at night, measured in the morning, and a few hours later 50% remained
  • If the subject was given MK-677, GH was nearly doubled when measured later in the day.
  • Capture
  • Impressive number considering they had only taken Mk-677 for FOUR days
    • It’s a lot to look at but the “24 hr Mean GH, Mean GH, and IGFs are important.



  •  I wish everything worked this well


  • So not only does it work, but it lowers cortisol and doesn’t effect prolactin.

MK-677 even increases bone density

Oral Administration of the Growth Hormone Secretagogue MK-677 Increases Markers of Bone Turnover in Healthy and Functionally Impaired Elderly Adults* M.G. MURPHY, M.A. BACH, THE MK-677 STUDY GROUP, D. PLOTKIN, J. BOLOGNESE, J. NG, D. KRUPA, K. CERCHIO, and B.J. GERTZ

(IGF-I in early-stage Alzheimer’s diesease: a potential therapeutic target?,  & )

The Literature regarding MK-677 efficacy is enormous, so much the case that it would be redundant to even include more here.

In Summary

  • MK-677
    • Acts as a ghrelin agonist
    • Stimulates brain regions involved with metabolic action
      • Dopamine
      • Opioid
      • Hypothalamus
      • Pituitary
    • Increases growth hormone levels
      • A single dose is effective
      • The longer MK-677 is taken the more effective it becomes
        • Has been used by subjects for up to two years in studies
        • Serum growth hormone increases are greater the longer the compound is used
    • Increases IGF levels
      • Increases muscle mass
        • Create more muscle cells
        • Signals cells to grow
      • Decrease fat mass
        • Similar action to insulin
          • Bring glucose into cells for use
          • Utilize fat stores as energy source
    • Faster healing
    • Firmer, healthier skin
    • Healthier hair
    • Works at any age

Personally, I’ve committed to a one year cycle of MK-677.  I have not taken it every single day, but I have lost 40 pounds, lift more, wake up earlier, have thicker hair, and have not noticed a single side effect.  It’s subtle, yet over time it’s made me feel super human in ways.  I don’t bruise anymore, cuts heal in days, I haven’t been sick, and somehow I have a higher tolerance for pain.  This last bit is just my 2 cents worth, but this compound is certainly one worth looking into.

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