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MK-677 (Ibutamoren): A Comprehensive Look at the Pros and Cons

MK-677 pros and cons

As we age, our growth hormone levels decrease. 

This is the reason why we lose muscle mass, gain weight, have poor quality sleep, and sometimes get the memory of a 70-year-old. 

If you are a bodybuilder, you know exactly how frustrating that is, especially if you want to boost your athletic performance and increase your gains. 

However, before you take any other supplements that promise to increase your hGH, grow your muscles, and help you lose weight…

Why not take a look at MK-677, a peptide developed in 1995 by Lumos Pharma?

In this article, we weigh MK-677 pros and cons to help you make the right choice

What is MK 677 (Ibutamoren) and How Does it Work?

MK-677 pros and cons

MK-677, also known as ibutamoren or ibutamoren mesylate, is a peptide that belongs to the growth hormone secretagogues group (GHSR). 

It works by mimicking the action of the hunger hormone ghrelin. It binds to one of the growth hormone secretagogue receptors (GHSR) in the brain, helping increase growth hormone (GH) levels. 

It also helps increase insulin-like growth factor 1 (IGF-1). 

IGF-1 is a hormone with a similar function and molecular structure to insulin. 

It boosts growth hormone levels with little to no effect on other hormones, such as cortisol, which can suppress the function of the immune system, brain, and memory. 

If you’re looking to increase your muscle growth without affecting your testosterone, MK-677 is a potent option. 

However, apart from muscle building, MK-677 offers other health benefits that you’ll surely be thankful for. 

MK677 Benefits

Now let’s go over the main benefits of MK-677.

MK-677 pros and cons

Improves Lean Muscle Mass and Strength

MK-677 can boost high levels of GH in the bloodstream by stimulating growth hormone release from the pituitary gland. 

This peak response is usually observed after taking MK-677, which helps in fat loss, muscle growth, and improved body composition.

Moreover, as an anabolic substance, MK-677 is believed to be a powerful peptide to help improve body composition and prevent muscle wasting due to medical conditions and old age.

In fact, men over 50 who took growth hormones, such as MK-677, also increased their muscle strength, especially in the lower body, after 6 months of therapy

 In this context, the use of GH in the healthy elderly should be an option for increasing muscle strength. 

Fourteen healthy men aged 50-70 years were evaluated at baseline for body composition and muscle strength (evaluated by leg press and bench press exercises, which focus primarily on quadriceps—lower body part and pectoralis major—upper body part—muscles, resp.). 

Subjects were randomized into 2 groups: GH therapy (7 subjects) and placebo (7 subjects) and reevaluated after 6 months of therapy. Thirteen subjects completed the study (6 subjects in the placebo group and 7 subjects in the GH group). 

After 6 months of therapy, muscle strength in the bench press responsive muscles did not increase in both groups but showed a statistically significant increase in the leg press responsive muscles in the GH group. 

Patients recovering from hip fractures were able to climb stairs and increase gait speed after 24 weeks of taking MK-677, according to the Archives of Gerontology and Geriatrics.

Previous studies with MK-0677 in hip fracture patients suggested possible benefits to functional recovery. This was a randomized, double-blind study of 123 elderly hip fracture patients assigned to receive 25 mg/day of MK-0677 or placebo. 

At 24 weeks, the mean stair-climbing power increased by 12.5 W in the MK-0677 group (95% confidence interval (CI) = −10.95–35.88; p = 0.292) compared with placebo. 

Gait speed increased by a 0.7-score difference in the means (95% CI = 0.17–1.28; p = 0.011). 

The MK-0677 group experienced fewer falls during the study compared to placebo and a smaller number of patients who had any falls (p = 0.096). 

Aside from muscle building, MK-677 can prevent muscle wasting in people with low levels of protein in their diet. 

In fact, those who took MK-677 helped reverse diet-induced nitrogen-wasting without any side effects.

Compared to the placebo, those who were given the peptide showed no increase in PRL and serum cortisol response.

A double-blind, randomized, placebo-controlled, two-period crossover study was designed to investigate whether MK-677, an orally active nonpeptide mimic of GH-releasing peptide, can reverse diet-induced protein catabolism. 

Eight healthy volunteers (ages 24-39 yrs) were calorically restricted (18 kcal/kg·day) for two 14-day periods. During the last 7 days of each diet period, subjects received either oral MK-677 25 mg or placebo once daily. 

There was a 14- to 21-day washout interval between periods. 

During the first week of caloric restriction (i.e. diet alone), daily nitrogen losses were similar for both treatment groups (mean ± SE; MK-677 group −2.67 ± 0.40 g/day vs. placebo group− 2.83 ± 0.26 g/day). 

During the second week (diet and study drug), mean daily nitrogen balance was 0.31 ± 0.21 g/day in the MK-677 treatment group compared with −1.48 ± 0.21 g/day in the placebo group (P < 0.01). 

MK-677 improved nitrogen balance integrated over the 7 days of treatment; area under the curve day 8–14 nitrogen balance response was +2.69 ± 5.0 (SE) for MK-677 and −8.97 ± 5.26 g·day for placebo (P < 0.001). MK-677 produced a peak GH response of 55.9 ± 31.7 μg/L after a single dose (day 1 of treatment) and 22.6 ± 9.3 μg/L after a week of dosing compared with placebo treatment peak GH values of approximately 9 (treatment day 1) and 7 μg/L (treatment day 7). 

Following the initial 7-day caloric restriction, insulin-like growth factor-I (IGF-I) declined from 232 ± 25 to 186 ± 19 ng/mL in the MK-677 group and from 236 ± 19 to 174 ± 23 ng/mL in the placebo group. 

Mean IGF-I concentration increased significantly during MK-677 to 264 ± 31 ng/mL (mean for the last 5 days of treatment) compared with 188 ± 19 ng/mL with placebo (P < 0.01). 

No significant difference in IGF binding protein-2 was found between the MK-677 and placebo treatments. 

Neither the serum cortisol nor the PRL response was significantly greater after 7 days of MK-677 dosing compared with 7 days of placebo. 

MK-677 (25 mg) was generally well tolerated and without clinically significant adverse experiences. 

This goes to show that MK-677 can help with catabolic conditions such as muscle wasting, especially in people with acute or chronic disease states.

Promotes Fat Loss

MK-677 can also help you lose stubborn fat.

In fact, in a study published in The Journal of Clinical Endocrinology and Metabolism (JCEM), obese males who were given an oral treatment of MK-677 for 2 months showed an increase in their basal metabolic rate (BMR), resulting in fat-free mass.

BMR refers to the rate at which the body uses energy while at rest. 

This is because MK-677 helps promote a sustained increase in GH, IGF-I, and IGF-binding protein-3 levels, which play huge roles in weight loss. 

Twenty-four obese males, aged 18-50 yrs, 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. Serum IGF-binding protein-3 was also significantly increased. 

GH and PRL (peak and area under the curve values) were significantly increased after the initial dose of MK-677. 

Significant increases, except 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. 

Fat-free mass increased significantly in the MK-677 treatment group when determined with dual energy x-ray absorptiometry or using a four-compartment model. 

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 but not at 8 weeks. 

Fasting concentrations of glucose and insulin were unchanged, whereas an oral glucose tolerance test showed impairment of glucose homeostasis at 2 and 8 weeks.

If you desire to lose weight and achieve a toned physique, taking MK-677 is a good idea.

Maintains a Healthy Skeletal Frame

If you’re looking to enhance bone strength and health, taking MK-677 can help increase your bone mineral density. 

Increased growth hormone and IGF-1 promote the development of new bone tissue and maintain bone mass, lowering your risk of fractures while promoting overall bone health. 

In a study in the Journal of Bone and Mineral Research, adults 65 years and older who took MK-677 once a day for two weeks showed improvement in bone-building and turnover. 

This means that old bone is removed (resorption) and new bone is formed (formation), helping maintain the strength and integrity of bones. 

Growth hormone (GH) stimulates osteoblasts in vitro. increasing bone turnover and stimulating osteoblast activity when given to elderly subjects. 

Probably a major effect of GH on bone is mediated through stimulation of either circulating or locally produced insulin-like growth factor I (IGF-I). 

We determined the effect of chronic administration of the GH secretagogue, MK-677, on serum IGF-I and markers of bone turnover in 187 elderly adults (65 years or older) enrolled in three randomized, double-blind, placebo-controlled clinical studies lasting 2–9 weeks. 

Urine was collected for determination of N-telopeptide cross-links (NTXs), a marker of bone resorption, and blood was collected for determination of serum osteocalcin and bone-specific alkaline phosphatase (BSAP), as bone formation markers, and serum IGF-I levels pre- and post-treatment. 

Dose response data was initially obtained in healthy elderly subjects who received oral doses of 10 mg or 25 mg of MK-677 or placebo for 2 weeks (n = 10–12/group). Treatment with 10 mg and 25 mg of MK-677 for 2 weeks increased mean urine NTXs 10% and 17%, respectively (p < 0.05 vs. placebo). 

Additionally, 50 healthy elderly subjects received either placebo (n = 20) for 4 weeks or 25 mg of MK-677 (n = 30) daily for 2 weeks followed by 50 mg daily for 2 weeks. MK-677 increased mean serum osteocalcin by 8% (p < 0.05 vs. placebo).

In both studies, MK-677 increased serum IGF-I levels significantly (55-94%). 

Subsequently, the biological effects of MK-677 were studied in 105 elderly subjects who met objective criteria for functional impairment. 

Subjects were randomized to receive oral doses of placebo for 9 weeks or either 5, 10, or 25 mg of MK-677 daily for an initial 2 weeks, followed by 25 mg of MK-677 daily for the next 7 weeks (n = 63 on MK-677 and n = 28 on placebo completed 9 weeks of therapy). 

Treatment with MK-677 (all MK-677 groups combined) for 9 weeks increased mean serum osteocalcin by 29.4%, BSAP by 10.4% (p < 0.001 vs. placebo), and mean urinary NTX excretion by 22.6% (p < 0.05 vs. placebo). 

The change from baseline serum osteocalcin correlated with the change from baseline serum IGF-I in the MK-677 group (r = 0.37; p < 0.01). In conclusion, once-daily dosing with MK-677, an orally active GH secretagogue, stimulates bone turnover in elderly subjects based on elevations in biochemical markers of bone resorption and formation.

This suggests that taking MK-677 consistently for years can result in improved bone mineral densities over time.

This is especially helpful in people over 50 years of age who are overweight or experiencing menopausal symptoms.

Improves Sleep Quality

As we age, we are at high risk of sleep problems that can impact our quality of life. 

Supplementing with the peptide MK-677 can boost the release of growth hormone, which helps promote good sleep quality and quantity.

It works by regulating the sleep-wake cycle and increasing the time spent in deep, restorative sleep stages.

Moreover, since GH can help in muscle repair, people who take MK-677 feel more recovered and energized when they wake up. 

This has been shown in several studies, including the one published in the Journal of Neuroendocrinology. 

Test subjects between 18 and 30 years who received MK-677 treatment for 14 days reported improvement in their sleep quality.

This is because the peptide helped increase the rapid eye movement (REM) sleep duration of the participants by 50%

Eight young subjects (18-30 years) followed a double-blind, placebo-controlled, three-period crossover design. Each subject participated in three 7-day treatment periods (with bedtime drug administration), presented in random (Latin square) order, and separated by at least 14 days. 

Doses were 5 and 25 mg MK-677 and matching placebo. 

Six older subjects, aged 65-71 years, each participated in two 14-day treatment periods (with bedtime drug administration) separated by a 14-day washout. 

Doses were 2 and 25 mg MK-677 during the first and second periods, respectively. 

Baseline sleep and hormonal data were obtained on the 2 days preceding the beginning of the first 14-day treatment period. In young subjects, high-dose MK-677 treatment resulted in an approximately 50% increase in the duration of stage IV and in a more than 20% increase in REM sleep as compared to placebo (p < 0.05). 

The frequency of deviations from normal sleep decreased from 42% under placebo to 8% under high-dose MK-677 (p < 0.03). 

In older adults, treatment with MK-677 was associated with a nearly 50% increase in REM sleep (p < 0.05) and a decrease in REM latency (p < 0.02). 

The frequency of deviations from normal sleep also decreased (p < 0.02). The present findings suggest that MK-677 may simultaneously improve sleep quality and correct the relative hyposomatotropism of senescence.

Therefore, if you want to improve your slumber for better recovery, MK-677 is a great option for a sleep peptide

Combats Aging and May Increase Longevity

Growth hormone naturally begins to decline as we age.

If you’re getting older, taking MK-677 can help support healthy amounts of GH and IGF-1 throughout the years. 

In fact, men and women over 65 years old who were given ibutamoren MK 677 daily had boosted GH and IGF-1 levels similar to healthy young adults, without experiencing any adverse side effects.

With placebo, mean (95% Cl) FFM decreased -0.5 kg; however, FFM increased 1.1 kg with MK-677.

Body cell mass as reflected by intracellular water decreased -1.0 kg with placebo but increased 0.8 kg with MK-677 (P=0.021). 

There were no significant differences in AVF or total fat mass. However, the average increase in limb fat in the MK-677 group (1.1 kg) was greater than with placebo (0.24 kg).

Body weight increased 0.8 kg with placebo and 2.7 kg with MK-677.

Fasting blood glucose increased by an average of 0.3 mmol/L (5 mg/dL) with MK-677 and insulin sensitivity declined. 

The most frequent side effects were an increase in appetite that subsided within a few months and transient, mild lower extremity edema and muscle pain. 

Low-density lipoprotein cholesterol decreased -0.14 mmol/L [-5.4 mg/dL] with MK-677.

Changes in bone mineral density consistent with increased bone remodeling occurred in MK-677-treated subjects. 

This goes to show that taking MK-677 consistently can help reverse some signs and symptoms associated with aging.

May Have Nootropic Effects

Similarly, ibutamoren MK 677 has been shown to have benefits to your brain. 

This is because the peptide MK-677 has the same attributes as ghrelin, such as binding with receptors in the brain. 

With this, MK-677 could be able to provide similar results on the brain as ghrelin.

Similarly, since MK-677 can help improve sleep quality, it can also help boost cognitive performance and brain health compared to those who don’t get restful sleep.

Moreover, it can boost IGF-1, which can help participants achieve high scores on cognitive tests, according to one study. 

Our findings demonstrate that sleep evoked by intracerebroventricular administration of GHRH during the dark phase is accompanied by significant increases in the number of GABAergic neurons in the MnPN and VLPO that express Fos protein IR. 

Antagonism of GHRH, with either intracerebroventricular administration of OCT or a competitive GHRH receptor antagonist during the light phase, caused suppression of sleep and reduced Fos+GAD immunoreactive cell counts in the MnPN and VLPO. 

In all of these conditions, increases or decreases in Fos+GAD-immunoreactive cell counts were accompanied by increases or decreases in sleep. 

Thus, the effects of drug administration on MnPN and VLPO neurons may have resulted in changes in sleep-wake amount. 

However, we found that intracerebroventricular GHRH administration significantly increased Fos expression in VLPO and MnPN GABAergic neurons when animals were not permitted to sleep. 

…the prevalence, distribution, and neurotransmitter phenotype of sleep-activated neurons in the medial preoptic nucleus are unknown. 

However, it is possible that sleep-wake effects of intracerebroventricularly-administered GHRH and GHRH antagonists involve changes in medial preoptic neuronal activity, as well as actions in the MnPN and VLPO.

While there aren’t any more studies supporting MK-677’s nootropic effect, scientists believe that indirect mechanisms, such as ibutamoren MK 677’s sleep benefits, could help provide a rationale for the way MK-677 could help improve cognitive health and functioning. 

Potential Side Effects of MK-677

MK-677 pros and cons

MK-677 is generally safe to use and has no recorded adverse side effects. 

However, people who reported joint pain, lethargy, increased appetite, and insulin resistance are those who took MK-677 at the wrong dosage or more prolonged use than prescribed.

This leads to unnaturally high levels of growth hormone in the body, resulting in several unwanted side effects. 

For example, if you have diabetes and are vulnerable to insulin sensitivity, MK-677 may not be the best peptide for you. 

Similarly, if you’re not planning to bulk up or gain weight, having an increased appetite might not be ideal. 

Moreover, people also reported water retention after taking MK-677 for a long time. This can lead to problems in the cardiovascular system over time. Therefore, if you have a heart condition, this could put your life at risk. 

However, you don’t have to worry. As long as you take peptide MK-677 properly at the right dosage and for the right amount of time, you will experience minimal to zero side effects at all. 

How to Safely Use Ibutamoren MK-677

MK677 is best administered sublingually, under the tongue, or through subcutaneous injection. 

You can use the sublingual dropper bottle liquid. 

Simply squeeze the right number of drops under your tongue, let it absorb for a few minutes, then swallow. 

What is the Optimal MK-677 Dosage?

You can take 10-25 mg of MK-677 once per day.

You may also want to split the dose into two or three smaller doses. 

When just starting with MK-677, take low doses at first, then gradually increase the dosage over time until you find the best dosage for you.

It’s best to talk to your doctor so they can provide you with the optimal and safest dosage for your needs.

This is because there are several criteria for identifying the right amount to take, including your weight, age, health status, and goals. 

You see, older adults need a lower dosage compared to younger adults. 

Similarly, if you have diabetes, it’s best to start with lower doses of MK-677 and gradually increase over time.

Lastly, if you’re looking to use the peptide for muscle growth, you will need a higher dosage. 

Therefore, how much you should take differs from person to person.

What Is a Good MK-677 Cycle Length?

When it comes to MK-677 cycles, there’s no one-size-fits-all answer.


Because there hasn’t been extensive human research on it yet.

However, from what we know anecdotally and from limited studies, people have used MK-677 continuously for up to 6 months without any noticeable side effects, sticking to around 30 mg per day.

To see the long-term MK677 benefits, you’d ideally use it continuously at lower doses. 

A popular cycle length for MK-677, especially when used alone, is around 10 weeks, followed by a four-week break to see how you feel before starting another cycle.

While the typical cycle lasts 8 to 12 weeks, some people push it to 16 weeks.

Just be careful, as going longer can lead to more side effects and less muscle growth.

It’s important to stick to the recommended dosages and cycle lengths to stay safe and get the most out of MK-677. 

After a cycle, take a break to let your body recover before thinking about starting the next one.

Comparing MK-677 vs. Growth Hormone Secretagogue Alternatives

MK-677 vs. CJC-1295

MK-677 pros and cons

MK-677 and CJC-1295 peptides can help boost growth hormone (GH) levels in your body.

However, they do so via different methods.

MK-677 works by mimicking the action of the hormone ghrelin, which can help boost GH levels by up to 300%.

On the other hand, the peptide CJC-1295 is a synthetic growth hormone-releasing hormone (GHRH).

This means that it’s produced by the hypothalamus and stimulates the pituitary gland to release GH by up to 200%.

Compared to CJC-1295, MK-677 can boost more insulin-like growth factor 1 (IGF-1) levels. 

However, CJC-1295 has a longer half-life compared to MK-677. This means that the former stays in the body for a longer time and has a more sustained release of GH.

Overall, both MK-677 and CJC-1295 are effective at boosting healthy GH levels. 

MK-677 vs. Ipamorelin

MK-677 and ipamorelin are both growth hormone secretagogues (GHS), meaning that they stimulate the pituitary gland to secrete growth hormone (GH). However, they do this differently. 

MK-677 is a non-peptide GHS – a small molecule that you can take orally. 

Ipamorelin, on the other hand, is a peptide GHS.

It is a chain of amino acids that binds to the growth hormone secretagogue receptor (GHSR). When this happens, it can help increase GH levels by up to 200%.

Compared to ipamorelin, MK-677 can increase insulin-like growth factor 1 (IGF-1) levels better.

This means that it can help in muscle building, bone health, and fat loss. 

However, ipamorelin has a longer half-life than MK-677.

MK-677 vs. Tesamorelin

MK-677 and tesamorelin can both increase growth hormone (GH) levels but in different ways. 

MK-677 mimics the action of the hormone ghrelin, while tesamorelin is produced by the hypothalamus and stimulates the pituitary gland to release GH by up to 200%.

Tesamorelin does not increase IGF-1 levels like MK-677 does, but it has a longer half-life than MK-677. 

Therefore, it stays in the body for longer, giving you a more consistent release of GH.

MK-677 vs. Sermorelin

MK-677 and sermorelin can both help boost your growth hormone (GH) levels. 

MK-677 works by mimicking the action of the hormone ghrelin, while sermorelin is produced by the hypothalamus and stimulates the pituitary gland, increasing GH levels by up to 200%.

Both peptides also increase insulin-like growth factor 1 (IGF-1) levels; however, MK-677 can boost it better. 

Between the two peptides, sermorelin has a longer half-life than MK-677.

Conclusion and Key Takeaways

MK-677 pros and cons

If you’re looking to build and grow your muscles and lose stubborn fat at the same time, MK-677 is a good option but IMO, not the best one as proven in the comparisons above with Ipamorelin, Tesamorelin and CJC-1295.

MK-677 has also been shown in multiple studies to improve sleep, decrease muscle wasting, and help with anti-aging.

But make sure to use MK-677 peptide as prescribed to avoid unwanted side effects.

For the best and purest MK-677 peptide, we recommend Limitless Life Nootropics, as they have some of the best formulations of MK-677 peptides on the market. 

That’s not to mention Limitless offers the BEST deals on both price and peptide purity.

Use code JAY15 at the checkout cart for 15% off!


But before you start injecting these two peptides into your body recklessly, make sure you first read the Top 10 Mistakes People Make When Starting Therapeutic Peptides FREE PDF!

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We’re excited to discuss biohacking, health, and life optimization through peptide therapy with you. See you on the other side!


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