Understanding MK-677: Benefits, Risks, and Potential Applications

In this article, we will take a close look at MK-677, also known as Ibutamoren, a potent, non-peptide agonist of the ghrelin receptor. We will explore its potential benefits in muscle building and fat loss, as well as its potential risks and side effects. We will also delve into the scientific studies that have been conducted on this compound and its potential applications.
Natasha Puttick

Natasha Puttick

Graduate medical student at Barts and London.

A blue image with text saying "MK-677"

What is MK 677?

MK 677, also known as Ibutamoren, is a potent, non-peptide agonist of the ghrelin receptor and a growth hormone secretagogue, mimicking the growth hormone-stimulating action of the endogenous hormone ghrelin.

It has been demonstrated to increase the release of, and produces sustained increases in plasma levels of several hormones including growth hormone and insulin-like growth factor 1 (IGF-1), but without affecting cortisol levels.

It has been suggested to increase lean body mass as well as muscle mass and strength. However, as discussed below potential risks include increased appetite, mild lower extremity edema, and muscle pain. Always consult with a healthcare professional before starting any new supplement regimen.

There is also evidence linking MK-677 and cancer, and MK-677 and brain damage, but the link is complex.


To understand how MK-677 compares to other substances such as follistatin, consider reading our blog comparing MK-677 vs follistatin.

MK 677 for Muscle Building and fat loss

MK-677 has been shown to sustain activation of GH-IGF-1 Axis and increase in lean body mass but no change in total fat mass or visceral fat. It is currently under development as a potential treatment for reduced levels of these hormones, such as in growth hormone deficient children or elderly adults, and human studies have shown it to increase both muscle mass and bone mineral density, making it a promising therapy for the treatment of frailty in the elderly. It also alters metabolism of body fat and so may have application in the treatment of obesity [1, 2, 3].

MK-677 and growing Muscle Mass

MK-677 has been shown to increase fat-free mass, or muscle mass, in certain populations. In a study involving healthy older adults, daily administration of MK-677 significantly increased growth hormone and IGF-I levels, and resulted in a significant increase in fat-free mass over a period of one year [4]. Similarly, in a study involving obese males, MK-677 treatment led to a significant increase in fat-free mass over a period of 8 weeks [5].

MK-677 and Muscle Strength

However, the increase in muscle mass does not necessarily translate to an increase in muscle strength. In the same study involving healthy older adults, the increase in fat-free mass did not result in changes in strength or function [4]. This suggests that while MK-677 may help increase muscle mass, it may not improve muscle strength or physical performance.

MK-677 and Body Fat

MK-677 may also have effects on body fat. In a study involving obese males, MK-677 treatment did not significantly change total and visceral fat, but the LDL-C/HDL-C ratio, a risk factor for cardiovascular disease, was reduced after 8 weeks of treatment [2]. In the study involving healthy older adults, no significant differences were observed in abdominal visceral fat or total fat mass [4].

Other possible benefits of MK-677

MK-677 has also been found to improve sleep quality. In a study involving both young and older adults, high-dose MK-677 treatment resulted in an approximately 50% increase in the duration of stage IV sleep and a more than 20% increase in REM sleep. The frequency of deviations from normal sleep decreased from 42% under placebo to 8% under high-dose MK-677 [3].

In postmenopausal osteoporotic women, MK-677 combined with alendronate, a bone resorption inhibitor, increased bone mineral density at the femoral neck by 4.2% compared to 2.5% for alendronate alone [6].

However, it's important to note that while MK-677 has shown potential benefits in these areas, more research is needed to fully understand its effects and potential side effects.

Possible risks of taking MK-677

Risks of taking MK-677 include impaired glucose homeostasis, decreased insulin sensitivity and impacts on the level of circulating LDL/HDLs.

In a study involving healthy obese males, MK-677 was administered daily for 8 weeks. While the treatment resulted in a sustained increase in serum levels of growth hormone, insulin-like growth factor I, and IGF-binding protein-3, it also led to an impairment of glucose homeostasis at 2 and 8 weeks [3].

Another study involving healthy older adults found that daily administration of MK-677 significantly increased growth hormone and insulin-like growth factor I levels. However, it also led to an increase in fasting blood glucose level and a decrease in insulin sensitivity. The most frequent side effects were an increase in appetite that subsided in a few months and transient, mild lower-extremity edema and muscle pain [1].

In a study involving obese subjects, MK-677 treatment affected circulating lipoproteins. At the end of the study, the LDL-C/HDL-C ratio was decreased - a factor of concern when looking at risk of developing heart disease [2].

It's important to note that these studies were conducted in controlled environments and the participants were closely monitored. If you're considering taking MK-677, it's crucial to consult with a healthcare provider to understand the potential risks and benefits.


While MK-677 may have benefits for bone growth and fat loss, the evidence does not strongly support its use as few comprehensive studies have been done in humans. More research is needed to fully understand the potential benefits and limitations of MK-677 in this context.

Crucially if you are thinking of taking these supplements, please consider the risks carefully and discuss with a licensed medical practitioner as they are often under-researched and the side effects ill understood. Additionally, some peptides are illegal to purchase in certain countries.

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Natasha Puttick

Natasha Puttick

Natasha is a medical student at Barts and the London school of Medicine and Dentistry, with an interest in the social determinants of health. She graduated from the University of Oxford with a BA in Human Sciences and has obtained two publications. Her most recent work investigating clinical vaccine trials has been published in BMJ Public Health.