The growth hormone market is full of products claiming to be as effective as the FDA-approved therapy with human growth hormone (HGH).
One of these products is a growth hormone secretagogue (GHS) called Ibutamoren (code names MK-677 and L-163,191). Sellers present it as a newer, safer, more convenient, and much more affordable therapy for low HGH.
Its popularity stems from the fact that there is no need for daily injections like other GHS or HGH. It’s an oral non-peptide HGH stimulant.
Yet, MK-677 is not FDA-approved, and research about its safety and effectiveness is scarce. You can buy the product only illegally and without any guarantee about its contents or possible risks.
In this article, we will break down the evidence so far and weigh in on all pros and cons of MK-677.
What is MK-677 and how does it work?
MK-677 belongs to a class of drugs that stimulate the pituitary gland into producing more HGH.
It is a GHS that mimics the hunger hormone (ghrelin). Ghrelin spikes when you are hungry and triggers the ghrelin receptors in the brain called growth hormone secretagogue receptors (GHS-R).
According to research, activating these receptors will increase your appetite, but also stimulate the pituitary gland to produce HGH which helps counteract low blood sugar while fasting.
Thus, MK-677 triggers the GHS-R by mimicking ghrelin and stimulates natural HGH production. Animal studies report that GH levels rise 30-40 minutes after oral administration of Ibutamoren and the effect continues for several hours.
The half-life of MK-677 is 4-6 hours which is significantly longer than most GHS. It’s orally active due to its non-peptide structure.
Ibutamoren leads to increased frequency in growth hormone pulses. Studies report that it also elevates the levels of insulin-like growth factor-1 (IGF-1). IGF-1 is the mediator of HGH’s anabolic effects.
For example, a trial with 65 elderly people (aged 60-81) showed that 25mg of MK-677 taken by mouth increases mean HGH and IGF-1 levels up to those of healthy young adults. The study also revealed that long-term Ipamorelin intake (up to 2 years) can successfully maintain high HGH and IGF-1 levels.
However, there is a lack of large studies investigating the effects of MK-677 in more diverse population groups. It is still a drug under investigation that’s not approved for marketing in the US.
Thus, any forms of Ibutamoren available on the market are illegal and unregulated.
What are the benefits of MK-677?
MK-677 is mainly investigated for the treatment of growth hormone deficiency (GHD) and muscle wasting. According to a trial in 32 healthy elderly people, ibutamoren leads to a 55% increase in IGF-1 levels at 2 weeks and 88% by 4 weeks.
However, only one study has investigated its effectiveness in patients with GHD. Young adults with childhood-onset GHD took 50mg of MK-677 for 4 days. The participants achieved IGF-1 levels comparable to the reference values for healthy elderly individuals.
Currently, we lack studies on Ibutamoren’s effects in children. One study reports that a week of MK-677 leads to an increase in HGH and IGF-1 levels but the exact effects on long-term growth remain unknown.
A study in younger obese individuals found that 2 months of therapy lead to 6 lbs. of lean mass gain, partially related to water retention. The scientists reported no significant changes in fat mass in the initial study or the follow-up.
The previously mentioned 2-years long trial with 65 elderly people reported 5-7 lbs. of weight gain for the whole period of the study. There were no changes in fat mass or muscle strength despite the increase in HGH secretion.
There are currently no studies investigating the effect of MK-677 on muscle wasting and cachexia
MK-677 also led to a slight reduction in LDL levels and an increase in bone mineral density. However, no significant functional improvements have been reported in patients with bone fractures.
In addition, some healthy people who took MK-677 reported improved deep sleep and decreased sleep latency.
What are the side effects of Ibutamoren?
The most commonly reported side-effect of MK-677 is an increase in appetite, which is a result of triggering the ghrelin receptors. However, the effect appears to be transient and decreases with prolonged use.
Ibutamoren also leads to transient elevation of cortisol, prolactin, and leptin levels, while thyroid hormones increase after 1-2 months of therapy. Furthermore, it may lead to decreased total testosterone (T) without affecting free T levels.
A long-term trial (lasting 2 years with 65 elderly) report musculoskeletal pain, water retention, increased blood sugar, and insulin resistance. Currently, the medication has not been used in patients with cancer and the risks remain unknown.
One study of MK-677 was terminated early due to a safety signal of congestive heart failure in a limited number of patients.
Due to its illegal status, there is also a high chance of counterfeit, diluted, and contaminated products. In fact, most illegal sellers wrongly label it as a SARM (selective androgen receptor modulator) – a class of drugs with similar anabolic properties to anabolic steroids.
What results to expect from MK-677?
MK-677 users share that they have experienced benefits such as improved recovery from training, improved muscle pump, and better sleep.
Many of them also took it in an attempt to heal sports traumas. Some users suggest that it helped them recover their joints and tendons after training injuries.
Most of the MK-677 users report variable results in muscle gain, fat gain, and water retention. That might be due to the illegal status of the medication and the lack of quality regulation.
Manufacturers can dilute it or add various substances, so you never know what effects to expect.
The main negative effects reported were headaches, hunger and sugar cravings, sleepiness, and water retention. Most users recommend taking Ibutamoren in the evening, due to the sleep-promoting effects as well as in an attempt to avoid extra hunger and weight gain.
On the other hand, when you start legal HGH therapy, you will be monitored by a medical doctor. An experienced endocrinologist will assess your results and the risk of side effects on every checkup.
If there are any concerns, your physician can make the necessary changes to ensure the safety and effectiveness of your treatment.
MK-677 vs HGH
Currently, scientists have investigated only the short-term effects of MK-677 on the HGH levels in GHD patients. Whether the drug has the potential to manage the symptoms of growth hormone deficiency remains largely unknown.
As most GHS, MK-677 might be completely ineffective in patients with a severely damaged pituitary gland that’s no longer able to produce HGH
Furthermore, it is not likely to help GHD patients manage symptoms such as abdominal obesity. Unfortunately, this is one of the main symptoms of the condition and often leads to long-term complications.
On the other hand, HGH therapy involves injecting exogenous recombinant growth hormone, and its effectiveness does not depend on the level of pituitary function. A large number of studies support its effectiveness in managing all symptoms of GHD.
Currently, it’s the only FDA-approved medication for treating the condition.
In terms of side effects, both HGH and MK-677 may increase water retention, blood sugar levels, and insulin resistance. However, Ibutamoren shows additional side effects, including sleepiness, increased hunger, sugar cravings, and transitory hormonal changes.
MK-677 vs Ipamorelin
Similarly, to MK-677, Ipamorelin is also a GHS that triggers the ghrelin receptor. However, it has a peptide structure and a significantly shorter half-life (about 2 hours). That’s why it must be injected subcutaneously, 2-3 times per day.
Ipamorelin effects and results appear to be more selective as it does not affect other hormones such as cortisol, prolactin, or leptin.
Ipamorelin also leads to a significant rise in hunger and food cravings, but unlike MK-677, it causes both lean mass and fat gain. Thus, you are much more likely to gain fat instead of losing it while on Ipamorelin.
MK-677 vs GHRP
The most notable growth hormone-releasing peptides (GHRP) include GHRP-2 and GHRP-6. They are also GHS which act by activating the ghrelin receptor.
The GHRP-2 has a half-life of about 30 minutes while GHRP-6’s half-life is 2-3 hours. Due to their peptide structure, they need to be injected several times daily.
GHRP-6 is the first growth hormone-releasing peptide developed and MK-677 is derived from its molecule.
Both GHRP-6 and GHRP-2 have been studied extensively compared to Ibutamoren
GHRP-2 has shown effectiveness in increasing growth velocity in GHD children. Besides, it is considered more potent than GHRP-6 in increasing mean HGH levels and IGF-1 levels.
GHRP-6 and GHRP-2 have similar effects to Ibutamoren as they lead to a significant increase in water retention, hunger, and weight gain. They are less selective than MK-677 and increase cortisol levels.