What is MK 677?
MK 677, or Ibutamoren, more commonly known, is a potent centrally active non-peptide growth hormone secretagogue and an agonist of the ghrelin receptor. It mimics the growth hormone-releasing effects of endogenous ghrelin.
It has been shown to release more and cause longer-lasting spikes in growth hormone, insulin-like growth factor 1 (IGF-1), and other hormones while leaving cortisol levels unaffected.
It is supposed to increase lean body mass, muscle mass, and strength. However, as discussed below, possible side effects include:
- Increased appetite
- Mild lower extremity oedema
- Muscle pain
Please consult with your healthcare provider before starting a new supplement regimen.
There is also evidence linking MK-677 and cancer, and MK-677 and brain damage, but the link is complex.
We encourage you to read our other blogs, MK-677 vs. follistatin, to comprehend how MK-677 relates to other substances.
MK 677 for Muscle Building and Fat Loss
MK-677 maintains activation of the GH-IGF-1 Axis to maintain lean body mass but leads to no alterations in total or visceral fat mass. It is under development for treating conditions with naturally reduced levels of these hormones, such as human studies finding that it increases both muscle mass and bone mineral density, making it potentially ideal for treating frailty in the elderly. It also metabolically modifies body fat, so potential areas of fat loss (such as ‘brown fat’) may be targeted, resulting in obesity treatment [1, 2, 3].
MK-677 and Growing Muscle Mass
MK-677 can augment fat-free or muscle mass in some patient populations. In a clinical trial on healthy older adults, daily administration of MK-677 resulted in a significant increase in growth hormone and IGF-I levels and fat-free mass over one year [4]. Another study with obese men found a similar increase in fat-free mass after eight weeks of treatment with MK-677 [5].
MK-677 and Muscle Strength
But greater muscle mass doesn’t necessarily lead to greater muscle strength. In another study in healthy older adults, increases in fat-free mass didn’t translate into changes in strength or function [4]. MK-677 could boost muscle mass, but it’s uncertain whether it will also increase muscle strength or physical performance.
MK-677 and Body Fat
MK-677 can also potentially impact body fat. In the study with obese males mentioned earlier, after 8 weeks of treatment, total and visceral fat remained the same. However, the LDL-C/HDL-C ratio (which indicates the risk of cardiovascular disease) was reduced [2]. In the study looking at healthy older adults, no differences were observed after 12 weeks in abdominal visceral or total fat mass [4].
Other Possible Benefits of MK-677
MK-677 has also been shown to enhance sleep quality. Overall, in the same study of humans, young and older adults on the same doses described previously, high-dose MK-677 treatment induced a roughly 50% increase in stage IV sleep time and a more than 20% increase in REM sleep. Total time spent outside of the regular pattern for sleep decreased from 42% under placebo to 8% under high-dose MK-677 [3].
Likewise, in postmenopausal osteoporotic women, MK-677, used in addition to alendronate, a drug that slows bone resorption, enhanced femoral neck bone mineral density by 4.2% as opposed to 2.5% for alendronate alone [6].
The critical thing to remember is that MK-677 holds promise in these areas, but much more research is necessary to understand its effects and potential side effects.
Possible Risks of Taking MK-677
Adverse effects of MK-677 use include impaired glucose homeostasis, decreased insulin sensitivity, and disturbances in circulating LDL/HDL levels.
In healthy obese males, daily administration of MK-677 for 8 weeks increased serum concentration of growth hormone, insulin-like growth factor I, and IGF-binding protein-3 – but also decreased glucose homeostasis at 2 and 8 weeks [3].
In a second trial, healthy ageing participants also experienced significant increases in growth hormone and IGF-1 with daily administration of MK-677; however, this was accompanied by a rise in fasting blood glucose levels and a fall in insulin sensitivity. The most common side effects were an increased appetite that subsided in a few months and initially mild transient discomforts such as lower-extremity oedema and muscle pain [1].
We noticed how treatment with MK-677 impacted circulating lipoproteins in obese subjects. At the end of the study, the ratio of LDL-C/HDL-C was decreased, which is one of the parameters of concern when considering the risk of cardiovascular disease [2].
Remember that all these studies were done in a controlled environment, and the subjects were closely monitored. If you’re considering taking MK-677, discussing it with a healthcare professional to assess the risks and potential benefits is always a good idea.
Conclusion
Because few broad studies have examined MK-677 in humans, it is unclear whether it will significantly affect bone growth and fat loss. We don’t know how much MK-677 offsets the natural decline in muscle mass and bone quality with age, particularly in humans. In short, we don’t know whether MK‐677 stands up to the hype about its supposed benefits, such as combating the growth hormone decline that causes weight gain as we age.
However, if you are thinking of using any of these supplements, please consider the risk, especially as they are largely under-researched, the side effects are poorly understood, and many peptides are illegal to buy in several countries.