Oral growth hormone enhancer MK-677 (ibutamoren)

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Nelson Vergel

Founder, ExcelMale.com
J Clin Endocrinol Metab. 1998 Feb;83(2):362-9.

Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure.

Svensson J1, Lönn L, Jansson JO, Murphy G, Wyss D, Krupa D, Cerchio K, Polvino W, Gertz B, Boseaus I, Sjöström L, Bengtsson BA.


Obesity is associated with blunted GH secretion, unfavorable body composition, and increased cardiovascular mortality. The objective of this study was to investigate the effects of oral treatment with the GH secretagogue MK-677 on GH secretion and body composition in otherwise healthy obese males. The study was randomized, double blind, parallel, and placebo controlled. Twenty-four obese males, aged 18-50 yr, with body mass indexes greater than 30 kg/m2 and waist/hip ratios greater than 0.95, were treated with MK-677 25 mg (n = 12) or placebo (n = 12) daily for 8 weeks. Serum insulin-like growth factor I (IGF-I) increased approximately 40% with MK-677 treatment (P < 0.001 vs. placebo). Serum IGF-binding protein-3 was also significantly increased (P < or = 0.001 vs. placebo). GH and PRL (peak and area under the curve values) were significantly increased after the initial dose of MK-677. Significant increases, with the exception of peak PRL, persisted at 2 and 8 weeks of treatment. The increases in GH and PRL after the initial dose were significantly greater than the increase seen after multiple doses. Serum and urinary concentrations of cortisol were not increased at 2 and 8 weeks (P = NS, vs. placebo). Fat-free mass increased significantly in the MK-677 treatment group when determined with dual energy x-ray absorptiometry (P < 0.01) or using a four-compartment model (P < 0.05). Total and visceral fat were not significantly changed with active therapy. The basal metabolic rate was significantly increased at 2 weeks of MK-677 treatment (P = 0.01) but not at 8 weeks (P = 0.1). Fasting concentrations of glucose and insulin were unchanged, whereas an oral glucose tolerance test showed impairment of glucose homeostasis at 2 and 8 weeks. We conclude that 2-month treatment with MK-677 in healthy obese males caused a sustained increase in serum levels of GH, IGF-I, and IGF-binding protein-3. The effects on cortisol secretion were transient. Changes in body composition and energy expenditure were of an anabolic nature, with a sustained increase in fat-free mass and a transient increase in basal metabolic rate. Further studies are needed to evaluate whether a higher dose of MK-677 or a more prolonged treatment period can promote a reduction in body fat.

For a list of studies and abstracts: Click here

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Defy Medical TRT clinic doctor


This is fascinating! Thank you Nelson.

Do you or does anyone else know of a good source for MK-677. I know several research chem sites offer it, but is there any one that stands out, or that anyone has used that they recommend?


Active Member
I have a friend who's bought sarms from www.sarmsx.com and says they're legit and work. I'm really curious about sarms too, especially GW-501516 and SR9009 for their endurance capabilities, but concerned about their oral bio-availability and long term safety.
"IGF-1 levels (the most accurate method of determining GH levels within the body) "

Not true.

The 24 urine GH assay is, beyond a doubt, the most accurate measure of GH status.


I tried mk-677 for a month and gained 10 lbs of water weight...freaked me out so stopped taking.

Wow - 10 lbs in a month is a LOT of water weight! I would have stopped it at that point as well. Did you notice any positives? I know 30 days is not really long enough for something like this to do much of anything, but I am curious none the less.


nothing of note other than water weight...it did drop off pretty quick once I stopped. Due to tennis elbow I think I am going to give it another go and will let you know if it helps heal elbow or not

Nelson Vergel

Founder, ExcelMale.com
Be careful. Growth hormone releasing peptides (just like growth hormone) are known for causing joint/muscle aches. Not a problem with ibutamoren since it bumps your cortisol during the first few weeks.
Be careful. Growth hormone releasing peptides (just like growth hormone) are known for causing joint/muscle aches.

I had terrible cramping, at night, as well as numbness in the hand, both primarily on the right side. Most nights is was bordering unbearable as in enough to wake me, then during the day the numbness was bothersome. This was with GRHP2/6/Ipam alone and in combinations 1-3 times a day. I had to quit without any tangible benefit for about 90 days I used those. I say that as water weight was mentioned and it's a known side effect with these peptides, too.
The one time I had it and couldn't shake it my Dr gave me a Cortisone(?) shot, 24hrs later I was good-to-go, though I've struggled with it for many months because I have a physical job and can't escape lifting/climbing and things like that so everyday it was a real bitch to deal with.


New Member
Just want to revisit this..

I have been researching this site and several others on MK-667 for the last few days and wondering several things.

1. I've read the study Nelson posted above but has anyone had any personal success with long term MK-667 use and if so could you share?
2. Could you share/recommend a reputable source or brand? I hate sending money to a supplier for a product that doesn’t have reviews.



Active Member
I'm doing daily MK-2866 for past 3 months, 20mg oral dose. Very effective at recover and repair, my shoulders swear by it. For years I had a severe impingement, and any attempts at shoulder presses would wreck them for a week. MK and now I've added S-4 have made a huge difference in my life. I can now do 185lb military presses. But you're right most of the sarms out there are bullshit. If it's a pill or capsule it's bullshit.


Wow, that is terrific! Especially impressive for rehabing your past injuries.

I have been using LGD-4033 for just over a month and it has done absolutely nothing at all, so I guess that I will give the MK-2866 a shot and hope for the best.


Thought I would contribute from a non human test subject friend ;)
MK-677 10mg 1st month then 20mg two months in three month IGF-1 went from
Insulin-Like Growth Factor I 215 73-243 ng/mL
Insulin-Like Growth Factor I 287 HIGH 73-243 ng/mL
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