Ipamorelin vs MK 677: Battle of the Top Peptides

When it comes to enhancing muscle mass, strength, and overall body composition, ipamorelin and mk-677 (also known as ibutamoren) are two popular options. Both of these substances have hormone secretagogue properties, which means they stimulate the release of growth hormone (GH) in the body. However, despite their similar mechanisms of action, there are some notable differences between the two that may influence their effectiveness and suitability for individual users. In this article, we are going to do a comprehensive review of ipamorelin vs mk 677.

Ipamorelin is a peptide and a selective GH-releasing hormone (GHRH) analog. It acts on the growth hormone-releasing hormone (GHRH) receptor in the pituitary gland to increase the secretion of GH. Unlike some other growth hormone secretagogues, ipamorelin doesn’t stimulate an increase in cortisol, prolactin, or testosterone. This selective action makes it an attractive option for those looking to improve their body composition and muscle mass without the negative side effects associated with other substances. When used in conjunction with CJC-1295, a synthetic GH-stimulating hormone analog, results can be even further enhanced. 

On the other hand, MK-677 (ibutamoren) is a non-peptide, orally active synthetic growth hormone secretagogue. It mimics the action of the hunger hormone, ghrelin, by binding to the ghrelin receptor to increase GH and insulin-like growth factor-1 (IGF-1) levels. Studies suggest that MK-677 users may experience fat loss, muscle strength improvements, and better sleep, among other benefits.

Key Differences
  • Ipamorelin is a peptide agonist of the ghrelin receptor, while MK 677 is a non-peptide agonist of the same receptor [1][2].
  • Ipamorelin has been shown to increase bone mineral content in rats, while the effect of MK-677 on BMC in animals is not mentioned in the available literature [2].
  • A clinical study found that ipamorelin was well-tolerated for the management of postoperative ileus, while the efficacy of MK-677 for this condition has not been studied [3].

Ipamorelin vs MK 677

In the world of growth hormone secretagogues, two names often come up: Ipamorelin and MK 677 (Ibutamoren). Both these compounds have gained popularity as potential aids for muscle growth, fat loss, and other health benefits. Let’s dive into the specifics of each to help you understand their differences.

Ipamorelin, a peptide hormone, is often used in conjunction with CJC 1295, another peptide. This combination is known to effectively stimulate the secretion of Growth Hormone (GH). Acting as a GHRP (Growth Hormone Releasing Peptide), Ipamorelin binds to ghrelin receptors and triggers the release of GH from the pituitary gland. Some key points to consider when using Ipamorelin include:

  • Minimal impact on cortisol, prolactin, and testosterone levels
  • Dose-dependent GH release
  • Reduced chance of side effects compared to other GHRP’s like sermorelin

On the other hand, MK 677 or Ibutamoren is a non-peptide, selective Growth Hormone Secretagogue (GHS) that has an effect on the ghrelin receptor. MK 677 bears similarities to SARMs (Selective Androgen Receptor Modulators) in its mechanism but isn’t a SARM itself. It’s orally active, meaning it doesn’t require injections like most peptides. MK 677 has a number of notable characteristics:

  • Significant increases in IGF-1 and GH levels
  • Longer half-life compared to Ipamorelin
  • Potential improvement in sleep quality

In terms of effects on the body, both Ipamorelin and MK 677 can positively impact muscle mass and body composition. Studies suggest that both compounds can help counteract muscle wasting and promote fat loss. However, MK 677 users often report an increase in appetite due to the ghrelin-related hunger hormone effect, which may cause unwanted fat gain if not managed properly.

When comparing Ipamorelin vs MK 677 regarding dosages, Ipamorelin is typically administered at a dose of 100-300 mcg per day, while MK 677’s common dosing lies around 10-25mg daily. Despite the easier administration of MK 677 (oral vs injection), its longer half-life may lead to prolonged GH elevation and, subsequently, undesired side effects.

Neither compound should be taken without consulting a medical professional, as individual responses to these secretagogues can vary. Additionally, the long-term effects of these compounds are not yet fully understood, so caution should be exercised with their use.

Comparing the main benefits and effects of Ipamorelin vs MK 677

Benefits Comparison

Let’s dive into the key differences and similarities between these two hormone secretagogues.


Ipamorelin is a growth hormone-releasing peptide (GHRP) that functions by promoting the secretion of GH from the pituitary gland. It’s often used in conjunction with CJC-1295, a growth hormone-releasing hormone (GHRH) analogue, for more potent effects. Some of the benefits provided by Ipamorelin include:

  • Improved muscle mass and strength
  • Reduced body fat
  • Increased bone density
  • Enhanced sleep quality

One of the significant advantages of Ipamorelin is its selective nature. It stimulates GH secretion without affecting cortisol, prolactin, or testosterone levels. Additionally, Ipamorelin users experience fewer side effects, such as less hunger stimulation compared to other GHRPs.

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MK-677 (Ibutamoren)

MK-677, or Ibutamoren, is a non-peptide growth hormone secretagogue that works by mimicking the action of ghrelin, the hunger hormone. As an orally active compound, Ibutamoren has a longer half-life than Ipamorelin and is known for boosting IGF-1 levels and GH levels. The benefits associated with MK-677 include:

  • Increased muscle mass and strength
  • Fat loss and improved body composition
  • Better deep sleep quality and longer restful periods
  • Decrease in sleep latency
  • Positive effects on bone mineral density and overall bone health

Long-term use of MK677 has been shown to help in the treatment of growth hormone deficiency, Alzheimer’s disease, and muscle wasting conditions. Although generally well-tolerated, MK-677 users should be aware of potential side effects such as increased hunger and blood insulin levels.

Comparing the Two

When comparing Ipamorelin and MK-677, several factors need to be considered. Some notable differences between the two compounds are:

TypePeptide (GHRP)Non-peptide
Secretion MechanismGHRH/GHRPGhrelin Receptor Agonist

Regarding their effects on muscle mass, body fat, and sleep quality, both Ipamorelin and MK-677 show positive outcomes. However, their method of action and administration route differs, making them suitable for different needs and preferences.

To sum it up, while both compounds offer similar benefits, Ipamorelin tends to be more selective and have fewer side effects, whereas MK-677 has a longer half-life and is easier to administer. It’s important to keep in mind that both compounds should only be used under the supervision of a medical doctor and after a thorough checkup to ensure safety and compatibility.

Comparing the potential side effects of Ipamorelin vs MK 677

Side Effects

When comparing two popular growth hormone secretagogues, Ipamorelin and MK677 (also known as Ibutamoren), it’s essential to understand the potential side effects. Both compounds stimulate the secretion of growth hormone (GH) and Insulin-like Growth Factor-1 (IGF-1), which can provide benefits such as improved muscle strength, body composition, and bone density. However, ipamorelin and MK-677 may differ in how they affect other hormonal levels and their potential adverse effects on the body.

Ipamorelin Side Effects

Ipamorelin is a peptide that functions as a ghrelin receptor agonist and selectively binds to Growth Hormone Releasing Hormone (GHRH) receptors. Compared to other growth hormone-releasing peptides (GHRP) such as CJC-1295 w DAC or sermorelin, ipamorelin has a far more selective mechanism of action, with a lower likelihood of causing side effects like a significant increase in cortisol, prolactin, or ghrelin levels.

Common side effects of Ipamorelin may include:

  • Mild increases in hunger or appetite
  • Water retention
  • Injection site irritation

MK-677 Side Effects

MK-677, also known as Ibutamoren, is a non-peptide, orally-active growth hormone secretagogue that closely mimics the action of ghrelin. It can significantly increase GH and IGF-1 levels but may also cause increases in cortisol, prolactin, and ghrelin levels. Consequently, users may experience more noticeable side effects, especially with prolonged use.

Some common side effects associated with MK-677 include:

  • Increased hunger (due to ghrelin stimulation)
  • Water retention and bloating
  • Sleepiness or lethargy, especially when taken in the evening
  • Transient elevation in cholesterol levels

A notable difference between these two compounds is the half-life. Ipamorelin’s shorter half-life necessitates more frequent dosing, while MK-677’s longer half-life allows for once daily administration, typically at a 10mg or 5mg dose. This can make MK-677 more convenient for users but may also increase the risk of prolonged side effects.

Given the differences in side effect profiles, individuals may prefer one compound over the other depending on their specific needs and goals. As with any supplement or medication, it’s critical to consult with a medical doctor before starting any regimen involving ipamorelin, MK-677, or other growth hormone secretagogues. Regular checkups and monitoring of hormone levels can help ensure the safe and effective use of these compounds for muscle growth, fat loss, and other potential benefits.

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When to choose Ipamorelin over MK 677 and vica versa

Ideal Use Cases

When comparing ipamorelin and MK-677 (ibutamoren), it’s essential to understand the differences in their use cases to determine which peptide is better suited for your needs. Both peptides can stimulate the secretion of human growth hormone (HGH), but their specific effects on the body, dosages, and mechanisms of action vary. In this section, we’ll explore the ideal scenarios in which each compound may excel.


Ipamorelin is a GH releasing peptide (GHRP) often used in combination with CJC-1295 to boost the secretion of insulin like growth factor 1 (IGF-1). Offering minimal side effects such as suppressed cortisol and prolactin levels, ipamorelin is an attractive option for users who prioritize safety. Here are some ideal use cases for ipamorelin:

  • Muscle mass: As a potent growth hormone releaser, ipamorelin promotes muscle growth, helping users reach their muscle mass objectives.
  • Reduced body fat mass: By stimulating the secretion of GH and IGF-1, ipamorelin can lead to reductions in body fat without affecting muscle mass.
  • Short-term use: Due to its relatively short half-life (2 hours), ipamorelin is best suited for short-term use. It’s typically taken multiple times per day in doses ranging from 100 to 300 mcg.
  • Stacking CJC 1295 and Ipamorelin: Ipamorelin’s effects can be enhanced when combined with CJC-1295, a growth hormone-releasing hormone (GHRH) analog. Together, these peptides stimulate a more significant GH release, leading to improved muscle growth, fat loss, and overall body composition.

MK-677 (Ibutamoren)

Contrary to ipamorelin, MK-677 is a growth hormone secretagogue, meaning it stimulates the release of GH by mimicking the hunger hormone, ghrelin. It also promotes IGF-1 production, but through different mechanisms and a longer half-life (24 to 48 hours), making it an orally active compound. Here are some ideal use cases for MK-677:

  • Bone density: Studies suggest that MK-677 might lead to increase in bone density, making it potentially useful for individuals with weakened bones or osteoporosis.
  • Restful sleep: Users often report better sleep quality when taking ibutamoren in the evening due to the hormone’s effects on melatonin and cortisol levels.
  • Long-term use: Given its longer half-life, MK-677 can be taken less frequently. A typical dose ranges from 10 to 25 mg per day and can be administered as a long-term therapy.
  • Treatment of growth hormone deficiency: Ibutamoren may have potential as a treatment for GH deficiency, with some studies showing its ability to improve growth in children.

While both MK677 and ipamorelin have their strengths, it’s vital to consult with a medical professional before using either peptide to ensure safety and monitor the effects on your body. Always perform regular checkups and blood tests during treatment.

Our final take on comparing Ipamorelin vs MK 677

Final Take

When comparing Ipamorelin and MK 677, it’s important to consider the differences between them and the desired effects on the body. Ipamorelin, a peptide growth hormone releasing hormone (GHRH) analogue, and MK 677, also known as Ibutamoren, a non-peptide growth hormone secretagogue, both aim to increase HGH and IGF-1 levels.


  • Less hunger stimulation compared to MK 677 (due to limited impact on ghrelin)
  • Lower chance of increasing cortisol, prolactin, and other hormones, resulting in fewer side effects
  • Typically administered through injections
  • Shorter half-life compared to MK 677 (2-3 hours)
  • Most users report less intense effects on muscle strength and body composition

MK 677

  • Stimulates hunger (due to its effects on the hunger hormone, ghrelin)
  • Higher possibility of influencing cortisol, prolactin, and other hormone levels, resulting in more side effects
  • Administered orally
  • Longer half-life compared to Ipamorelin (24 hours)
  • Most users report faster and more dramatic effects on muscle pump strength, body composition, and fat loss

Here’s a table to better visualize the differences between them:

PropertyIpamorelinMK 677
Method ofInjectionOral
Half-Life2-3 Hours24 Hours
Hunger StimulationLessMore
Growth HormoneMore Selective and │Potent 
Influence on OtherMinimalWider Impact

Based on this comparison, many users may favor MK 677 for its oral administration, longer half-life, and stronger effects on muscle strength and fat loss. However, some individuals may prefer Ipamorelin for its more selective impact on growth hormone secretion without affecting other hormones as much.

Ultimately, it’s essential to consider factors such as personal preference, risk tolerance, and desired effects when deciding between Ipamorelin and MK 677. It’s also crucial to consult with a medical doctor before starting any new supplementation or treatment, particularly for those with existing medical conditions or hormone imbalances.

Frequently Asked Questions


What are the differences between Ipamorelin and MK 677 in terms of IGF-1 production?

Ipamorelin is a peptide that selectively increases IGF-1 levels by stimulating the release of growth hormone from the pituitary gland. MK 677, also known as Ibutamoren, is an orally active growth hormone secretagogue that mimics the action of ghrelin and also increases IGF-1 levels. Both Ipamorelin and MK 677 can lead to increased IGF-1 production, but they act through different mechanisms and pathways.

How does Ibutamoren (MK677) affect body composition as compared to Ipamorelin?

Both Ipamorelin and MK 677 have been studied for their effects on body composition. Studies suggest that Ibutamoren (MK 677) may have a more significant impact on body composition by increasing lean body mass and potentially reducing fat mass. On the other hand, Ipamorelin has also shown positive effects on body composition, but its results may be less pronounced than that of MK 677.

Can Ipamorelin and CJC 1295 be used together with MK 677?

Yes, Ipamorelin and CJC 1295 can be used together with MK 677. Some users combine these peptides to maximize the benefits of IGF-1 and growth hormone secretion, which can potentially lead to improved muscle growth, increased bone density, and better overall body composition. However, it is essential to follow the recommended dosages and consult a healthcare professional before combining these peptides to minimize any potential side effects or interactions.

How do Ipamorelin and MK 677 impact bone density?

Both Ipamorelin and MK 677 have shown potential benefits in improving bone density. Ipamorelin has been found to increase growth hormone and IGF-1 levels, which are essential for promoting bone growth and improving bone density. Similarly, MK 677 has demonstrated positive effects on bone turnover markers in animal studies, suggesting its potential to support bone health as well.

How safe are Ipamorelin and MK 677 compared to other oral growth hormone supplements?

While more research is needed to determine the long-term safety of Ipamorelin and MK 677 fully, current studies suggest that these peptides are generally well-tolerated and may be considered safer than other oral growth hormone supplements. Ipamorelin is known for having minimal side effects and a lower risk of triggering an increase in cortisol and prolactin levels compared to other growth hormone-releasing peptides.

Is it possible to use Ipamorelin as a substitute for TRT (Testosterone Replacement Therapy)?

While Ipamorelin can lead to increased IGF-1 and growth hormone levels, it does not directly affect testosterone levels. As a result, Ipamorelin should not be considered a substitute for TRT for those with low testosterone levels or experiencing symptoms of low testosterone. Consulting a healthcare professional is recommended to explore proper treatment options for testosterone replacement therapy.

How do insulin levels and pancreas function relate to the use of Ipamorelin and MK 677?

Both Ipamorelin and MK 677 can impact insulin levels as they influence the secretion of growth hormones. Insulin is produced by the pancreas, and growth hormone can affect how the body processes insulin, potentially leading to changes in insulin sensitivity. However, more research is needed to determine the exact relationship between Ipamorelin, MK 677, and their effects on insulin levels and pancreas function.

Does GRF 1-29 have any advantages over Ipamorelin and MK 677?

GRF 1-29, also known as Sermorelin, is another peptide that stimulates growth hormone secretion. While it shares some similar effects with Ipamorelin and MK 677, such as promoting muscle growth and improved body composition, GRF 1-29 has a shorter half-life and may require more frequent dosing. Choosing between GRF 1-29, Ipamorelin, or MK 677 may depend on individual preferences, goals, and any potential side effects experienced with each peptide.

At what stage of a fitness program should one consider using Ipamorelin or MK 677?

There is no specific stage at which one should consider using Ipamorelin or MK 677. The decision to use these peptides might depend on individual goals, such as muscle growth, fat loss, or improved bone density. It is important to have a solid exercise regimen and a nutrition plan in place before considering adding peptides like Ipamorelin or MK 677 to one’s fitness program. Consulting a healthcare professional is also advised before starting any new supplements or peptides.

Is there a difference in HGH levels after using Ipamorelin vs. MK 677?

Both Ipamorelin and MK 677 are designed to stimulate HGH secretion, leading to increased HGH levels in the body. However, the degree of increase in HGH levels may vary depending on the individual and the dosage used. Some studies suggest that MK 677 may cause a more significant and sustained rise in HGH levels compared to Ipamorelin, but more research is needed to compare the efficacy of these peptides directly.


  1. Philip, M., Khader, K., Subhahar, M., Perwad, Z., Karatt, T. (2021). Characterization Of Equine Liver Microsome‐generated Metabolites Of Growth Hormone Secretagogue Small Molecule Ibutamoren. Rapid Commun Mass Spectrom, 23(35).
  2. Svensson, J., Lall, S., Dickson, S., Bengtsson, B., Rømer, J., Ahnfelt-Rønne, I., … & Jansson, J. (2000). The Gh Secretagogues Ipamorelin and Gh-releasing Peptide-6 Increase Bone Mineral Content In Adult Female Rats. Journal of Endocrinology, 3(165), 569-577.
  3. Beck, D., Sweeney, W., McCarter, M. (2014). Prospective, Randomized, Controlled, Proof-of-concept Study Of the Ghrelin Mimetic Ipamorelin For The Management Of Postoperative Ileus In Bowel Resection Patients. Int J Colorectal Dis, 12(29), 1527-1534.
Chris Jackson
Chris Jackson

Chris Jackson, co-founder of Sarms.io, is a renowned fitness blogger, physique model, and evolutionary bioscience researcher specializing in SARMs (Selective Androgen Receptor Modulators). His extensive work, characterized by cutting-edge research and practical training advice, has made Sarms.io a leading source for accurate, credible information on performance enhancers. With a dedication to improving the understanding and application of SARMs in optimizing human performance, his contributions have not only expanded public awareness but also shaped the conversation around these substances. Chris's pursuit of knowledge and commitment to sharing it continue to inspire many in their fitness journeys.

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