YK-11 Pros and Cons for Extra Muscle Growth!

Myostine, Myostane, YK11 is an innovative supplement from the group of SARMs, which helps unlock the genetic code and opens new horizons for muscle growth, fat burning, and improved body composition. YK-11’s action is based on blocking myostatin (myostatin inhibitor), an inhibitor of muscle growth in the human body. When you are on a Myostane solo cycle, anabolic indicators go off the scale.

It is important to note that there are no side effects associated with AAS. Keep reading to learn about all of YK-11’s pros and cons for bodybuilders.

YK-11 was made so that everyone could achieve desirable muscle volume without the use of hormones. It’s happened to everyone: you go to the gym, you follow the diet, you lift heavy, you recover enough, and the muscle grows.

But one day, the process stops, and no training plans, diets, or exercises do not help. The innovative product will help “break through the plateau” for almost any athlete.

YK-11 is a dihydrotestosterone derivative, 5α-DHT. But while DHT, when ingested, simply replaces what our hormonal system produces and accelerates muscle growth, 5α-DHT works as a SARM.

Read the whole YK 11 review to know the pros and cons of using it.

How is YK11 blocking myostatin?

Old-timers of “the iron world” know exactly what a regulatory protein called myostatin is. Those hearing about this peptide for the first time should get to know it better.

Myostatin has a very specific function not only in the human body but also in many mammals. It blocks muscle growth. You heard it right, myostatin blocks muscle fiber growth.

Myostatin’s only function is to slow the growth of muscle mass so that the animal or person does not become a pile of unwanted muscle that cannot be fed and that ligaments and joints cannot hold.

According to comprehensive research published in PNAS (Proceedings of the National Academy of Sciences), [Lee & McPherron, 2008] examining long-term enhancement of skeletal muscle mass by myostatin inhibitors: “Various myostatin inhibitor approaches have been tested in models of muscle disease with varying efficacies, demonstrating a promising therapeutic strategy for musculoskeletal disorders. Single gene administration of myostatin inhibitors in aged animals resulted in sustained increases in lean muscle mass and strength, demonstrating a therapeutic strategy that warrants consideration for clinical trials in human muscle diseases.”

Experiments on animals have shown that turning off myostatin receptors leads to an increase in lean muscle mass. People have been known to have a mutation in the gene encoding myostatin. All of them were characterized by abnormal (strong) development of muscle mass.

What is the selective androgen receptor regulator YK11 doing with myostatin?

The mechanism of action of these SARMs is implemented through receptors for androgens, and the result of YK11’s interaction with these receptors is the production of follistatin, another signaling protein whose task is to deactivate myostatin.

According to research published in the journal Bioorganic & Medicinal Chemistry, [Kanno et al., 2013] on selective androgen receptor modulator YK11 and myogenic differentiation: “YK11 significantly increased the mRNA levels of myogenic regulatory factors (MRFs) compared with DHT, an AR full agonist. YK11 demonstrates unique selective induction of follistatin mRNA, which was not shown by DHT. This mechanism of action—through AR-dependent induction of follistatin expression—enables YK11 to enhance myogenic differentiation and muscle growth distinct from traditional androgen signaling.”

It turns out that YK11 stimulates the synthesis of muscle growth “inhibitor blockers”. That is, it increases the level of a regulator in the muscle that suppresses the activity of another regulator that blocks muscle growth. The result of this double action is obvious: rapid muscle mass gain!

According to Nature research published in 2021, [Muramatsu et al., 2021] on novel myostatin-specific antibody enhanced muscle performance: “Myostatin-targeted therapy maximizes the potential for muscle disease treatment. A novel antibody (GYM329) that specifically binds the latent form of myostatin and inhibits its activation demonstrated superior muscle strength-improvement effects in three different mouse disease models compared to conventional anti-myostatin agents. Treatment resulted in dramatic improvements in muscle mass, strength gains, and muscle performance across Duchenne muscular dystrophy, spinal muscular atrophy, and disuse muscle atrophy models.”

Myostatin is a reliable aid for classic SARMs like Ibutamoren, and Ligandrol. But it can also be taken solo since it has none of the side effects of dihydrotestosterone.

The substance increases the production of protein kinase, the enzyme responsible for strengthening bones. It promotes not only the growth of muscle mass but is also a means of preventing osteoporosis.

The Effects of Myostine (YK11) on Bodybuilding

YK11 is the newest “drug” in the world of sports pharmaceutics, but the results of the first experiments are impressive.

According to comparative research published in Bioorganic & Medicinal Chemistry, [Yatsu et al., 2018] examining YK11 and DHT anabolic effects on osteoblast cells: “Treatment of YK11 and dihydrotestosterone (DHT) accelerated cell proliferation and mineralization in mouse osteoblast cells. YK11-treated cells increased osteoblast-specific differentiation markers such as osteoprotegerin and osteocalcin compared to untreated cells. YK11 activates Akt-signaling via non-genomic signaling of AR, suggesting YK11 has osteogenic activity with strong anabolic effects comparable to androgens.”

When comparing the effects of identical doses of testosterone and YK11 in laboratory conditions, it was found that anabolic processes in muscle cells were greater when YK11 was used. In other words, YK11 is at least as strong as testosterone in anabolic activity without the side effects of AAS.

Even a solo cycle of YK11 increases muscle, which is demonstrated by the increased anabolic markers in the muscle tissue. Experiments have shown that blocking myostatin receptors leads to a dramatic increase in lean mass with no increase in fat tissue. Moreover, myostatin blockers have a lipolytic effect, which is manifested in accelerated fat burning.

According to Nature Scientific Reports, [Gangopadhyay et al., 2013] examining systemic administration of follistatin and muscle growth: “Daily subcutaneous injection of mice with recombinant follistatin288 showed dose-dependent increases in body lean mass and significant increases in muscle mass within thirteen weeks. The data indicate increased muscle mass caused by increased average size of muscle fibers. A dose-dependent increase in lean mass occurred, together with an associated significant decrease in body fat mass, demonstrating metabolic changes and muscle fiber type switching through myosin heavy chain remodeling at the molecular level.”

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Using Myostane in bodybuilding, fitness, and strength athletics:

• mass gain;
• slimming;
• cutting;
• getting ready for a competition;

Warning! Myostine is not suitable for the prevention of sports injuries. Myostatin blockage leads to accelerated growth of skeletal muscles, which precedes strengthening of joint and ligament apparatus, and this can increase the risk of injury.

The Pros of YK11 SARM

• Rapid muscle mass gain
• There is no water retention.
• Results without “rollback” after the cycle;
• Increased strength, endurance, and maximum power;
• There was no increase in estrogen levels or risk of gynecomastia.
• It does not inhibit the synthesis of endogenous testosterone;

No side effects are common with testosterone, dihydrotestosterone, and their synthetic derivatives.

The Cons of Taking YK-11 SARM

Here are the main disadvantages of using the SARM:

• There is limited research on YK-11’s long-term effects on human health.
• It may cause liver damage and other adverse effects. According to clinical case reports published in the Journal of Hepatology, [Koller et al., 2021] on liver injury associated with SARMs: “Reports document two cases of liver injury in young men who used ligandrol and/or ostarine for a few weeks. The precise mechanisms of liver injury caused by SARMs remain unclear, but extensive metabolism and exposure to high doses likely generate metabolites susceptible to haptenization and secondary immune response. Hepatocytes and cholangiocytes were targeted by the immune response, with mixed-type injury patterns observed.”
• It is not approved for human use by the FDA.
• It may cause suppression of natural testosterone production.
• It may cause acne and other skin issues.

The Right Dosage: How to Take Myostatin Inhibitor?

The recommended YK 11 dosage is 2 capsules per day, divided into two doses of 1 capsule. The cycle duration is 4 to 8 weeks.

Is YK-11 SARM and Anabolic Steroid?

YK-11 is a selective androgen receptor modulator (SARM) that selectively binds to androgen receptors in muscle and bone tissue, increasing muscle mass and bone density. It works by stimulating the production of follistatin, a protein that inhibits myostatin and limits muscle growth.

On the other hand, anabolic steroids are synthetic versions of the male hormone testosterone that promote muscle growth, bone density, and strength. They bind to androgen receptors in various tissues, including muscle, bone, and the liver, leading to increased protein synthesis and muscle mass.

The main difference between YK-11 and anabolic steroid is that YK-11 is more selective in its action, targeting only muscle and bone tissue, while anabolic steroids affect various tissues in the body. YK-11 has fewer side effects than anabolic steroids, making it a safer alternative for bodybuilding and athletic performance enhancement.

The Studies

YK-11 is a synthetic steroidal selective androgen receptor modulator (SARM) that has been studied for its potential to prevent muscle loss and decrease fat mass. It has also been described as having myostatin inhibitor-like properties.

According to a 2024 study published in Nutrients, [Dahleh et al., 2024] examining YK11 effects on hippocampal neurochemistry and memory: “YK11, at anabolic doses, significantly alters hippocampal neurochemistry, leading to impairments in memory consolidation. The study found that YK11 displayed high binding affinity with AR in the hippocampus, influencing neurochemical function and modulating aversive memory consolidation. YK11 increased pro-inflammatory IL-1β and IL-6 cytokines while reducing anti-inflammatory IL-10 levels, raising concerns about the misuse risks of SARMs among athletes.”

While it has shown promise in animal studies as a potential treatment for sepsis-induced muscle wasting, there needs to be more scientific data on its metabolism because it is an experimental drug candidate and a non-approved substance for humans.

However, there are concerns about the lack of testing and licensed researchers studying YK-11.

There are 14 trials of thymosin beta 4 in the clinical trials database (ClinicalTrials.gov).

References

1. Dahleh, M.M.M., et al. (2024) – “From Gains to Gaps? How Selective Androgen Receptor Modulators Affect Brain and Behavior” published in Nutrients. The 5-week experimental study found that YK11, at anabolic doses, significantly altered hippocampal neurochemistry leading to impairments in memory consolidation. YK11 increased pro-inflammatory IL-1β and IL-6 cytokines while reducing anti-inflammatory IL-10 levels, raising concerns about SARM misuse risks and challenging perceptions of minimal side effects. [Dahleh et al., 2024]
2. Gangopadhyay, S.S., et al. (2013) – “Systemic Administration of Follistatin288 Increases Muscle Mass and Reduces Fat Mass in Mice” published in Nature Scientific Reports. The study documented that daily subcutaneous injection of mice with recombinant follistatin288 resulted in dose-dependent increases in body lean mass and significant increases in muscle mass within thirteen weeks, with increased muscle mass caused by increased average size of muscle fibers and associated significant decrease in body fat mass. [Gangopadhyay et al., 2013]
3. Kanno, Y., et al. (2013) – “Selective Androgen Receptor Modulator, YK11, Regulates Myogenic Gene Expression” published in Bioorganic & Medicinal Chemistry. The study demonstrated that YK11 significantly increased the mRNA levels of myogenic regulatory factors (MRFs) compared with DHT, an AR full agonist. YK11 demonstrated unique selective induction of follistatin mRNA, which was not shown by DHT, indicating a distinct mechanism of action through AR-dependent induction of follistatin expression enabling enhanced myogenic differentiation. [Kanno et al., 2013]
4. Koller, T., et al. (2021) – “Liver Injury Associated with the Use of Selective Androgen Receptor Modulators (SARMs)” published in the Journal of Hepatology. The clinical case report documents two cases of liver injury in young men who used ligandrol and/or ostarine for a few weeks. The study notes that precise mechanisms of liver injury caused by SARMs remain unclear, but extensive metabolism and exposure to high doses likely generate metabolites susceptible to haptenization and secondary immune response, with hepatocytes and cholangiocytes targeted by immune response. [Koller et al., 2021]
5. Lee, S.J., & McPherron, A.C. (2008) – “Long-Term Enhancement of Skeletal Muscle Mass and Strength by Single Gene Administration of Myostatin Inhibitors” published in Proceedings of the National Academy of Sciences (PNAS). The comprehensive study demonstrated that various myostatin inhibitor approaches tested in models of muscle disease show varying efficacies with promising therapeutic strategy for musculoskeletal disorders. Single gene administration of myostatin inhibitors in aged animals resulted in sustained increases in lean muscle mass and strength. [Lee & McPherron, 2008]
6. Muramatsu, H., et al. (2021) – “Novel Myostatin-Specific Antibody Enhances Muscle Growth and Strength” published in Nature Scientific Reports. The study describes a novel antibody therapeutic approach (GYM329) that specifically binds the latent form of myostatin and inhibits its activation. GYM329 and its murine functional equivalent exhibited superior muscle strength-improvement effects in three different mouse disease models (Duchenne muscular dystrophy, spinal muscular atrophy, and disuse muscle atrophy) compared to conventional anti-myostatin agents. [Muramatsu et al., 2021]
7. Yatsu, T., et al. (2018) – “Selective Androgen Receptor Modulator, YK11, Up-Regulates Osteoblastic Differentiation and Mineralization: Comparison with Dihydrotestosterone” published in Bioorganic & Medicinal Chemistry. The study demonstrated that YK11 and DHT treatment accelerated cell proliferation and mineralization in mouse osteoblast cells, with YK11-treated cells showing increased osteoblast-specific differentiation markers such as osteoprotegerin and osteocalcin. YK11 activated Akt-signaling via non-genomic AR signaling similar to DHT, suggesting strong anabolic effects. [Yatsu et al., 2018]
8. World Anti-Doping Agency (2025) – “2025 Prohibited List” published by WADA. The official WADA 2025 Prohibited List classifies YK-11 as a prohibited anabolic agent under the category of “Anabolic Agents.” The prohibition states: “All SARMs, including but not limited to S-23 and YK-11, are prohibited at all times (in- and out-of-competition).” YK-11 is banned because it is designed to enhance physical capabilities. [WADA, 2025]

Research Team

The BoostHormone Research Team is a collective of fitness researchers, nutrition specialists, and health science professionals dedicated to providing evidence-based information about hormone optimization and performance enhancement.

With expertise in sports nutrition, endocrinology, and supplement science, our team analyzes peer-reviewed research and clinical studies to deliver honest, science-backed insights. We cut through industry hype to provide the accurate information you need to make informed decisions about your health and performance.

Our mission: translate complex scientific research into practical, actionable guidance – always prioritizing your safety and long-term wellness. Read Our Editorial Guidelines.

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