YK-11 Review: Is It A SARM Or Prohormone?

By: Rob Miller
1 User Reviews
Fact Checked On: 11-21-2020

Home » SARMS » YK-11 Review: Is It A SARM Or Prohormone?


What is YK-11
YK-11 as a S.A.R.M.
YK-11 as a Prohormone
YK-11 as a Myostatin Inhibitor
Is YK-11 Legal to Buy and Use
How Does YK-11 Work
Side Effects of YK-11
What Does Science Say about YK-11
Highlighted Benefits of YK-11
How to Use YK-11
Stacking Methods with YK-11

Note: This is just a review. Click Here to buy YK-11 legally online.

Do you want to pack on muscle mass?

Not interested in wasting money on any more useless supplements?

Ready to put on lean muscle mass while promoting fat loss?

It can be tough to keep up with all of the muscle building options out there. From prohormones to S.A.R.M.s to steroids, the market is flooded with a variety of muscle-focused supplements; however, not of these supplements are able to deliver on their promises.

Many of them claim to be miracle cures to any number of workout recovery problems or simply be the ultimate and most essential tool to pack on bulk that you have been missing out on all this time.

YK-11 is a relatively new muscle building compound that has been famously falsely categorized as a S.A.R.M. and a prohormone. Despite what you may read, YK-11 is neither of these things and yet it shows an immense amount of potential for being a powerful tool to build mass while reducing fat.

Let’s take a look at what YK-11 is, how it compares with other anabolic supplements, and how you can use it to achieve muscle mass and fat loss.

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1.  What is YK-11?

yk-11 reviews

This is the question that can lead you down a rabbit hole on a Google search bar.

Is YK-11 a selective androgen receptor modulator? No.

Is YK-11 a prohormone? No.

What exactly is YK-11?

Due to its properties and the way it works once it is inside your body, YK-11 can be appropriately classified as a Myostatin Inhibitor. Let’s first jump into why it’s not a S.A.R.M. or a prohormone.

2.  YK-11 as a S.A.R.M.

What is YK-11

A selective androgen receptor modulator, best known as a S.A.R.M., is a compound that targets specific androgen receptor sites in the body and promotes anabolic benefits with minimal androgenic side effects.

YK-11 is not a S.A.R.M. but I can see why it is usually classified as such. YK-11 does attach itself to androgen receptors; however, it does not promote the release of anabolic or androgenic agents. Instead, once attached YK-11 promotes the release of Follistatin. More on the relationship between Follistatin and Myostatin below.

3.  YK-11 as a Prohormone

YK-11 as a Prohormone

A prohormone is ingested into the body where it will be given the missing compound to turn it into an active androgenic agent. Most prohormones will promote both anabolic benefits such as muscle growth while also triggering androgenic side effects such as acne and aggression. Prohormones also are known for causing testosterone suppression and requiring a post-cycle therapy supplement to offset these effects.

YK-11 does not require a missing compound in order to be activated. Rather, once inside the body, it connects to an androgen receptor and it promotes the release of the compound, Follistatin. It does have some side effects, which I’ll expand on below, but nothing as severe as a prohormone.

Prohormones and YK-11 have completely different mechanisms for activation along with a different level of anabolic versus androgenic effects. In summary, YK-11 is NOT a prohormone.

4.  YK-11 as a Myostatin Inhibitor

YK-11 as a Myostatin Inhibitor
Source: moreplatesmoredates.com

YK-11 is a myostatin inhibitor. First, let’s breakdown what myostatin is and its role in muscle building.

Everyone has a genetic muscle building limit. If we didn’t have a genetic wall in place, our bodies would continue to gain muscle mass to the point of not being able to physically move because the mass would be so big, assuming the right conditions were met for hypertrophy, of course.

Myostatin is in charge of being that muscle building wall. Men and women are able to max out their genetic potential and once they reach that point, even with the best diet and training program, myostatin will step in.

Myostatin inhibitors are able to disarm the compound and allow your body to continue making progress. More on how YK-11 acts as a myostatin inhibitor below.

Is YK-11 Legal to Buy and Use

YK-11 seems to be somewhere in the gray area of legality. It all depends on what form of YK-11 you’re after.

If you want official medical grade YK-11, you must be involved with a research laboratory currently conducting studies on the compound.

If you aren’t a research scientist, not to worry. You can purchase unregulated YK-11 online. As I’ve mentioned in several other articles, unregulated supplements don’t always contain what is advertised. The best way to purchase an unregulated supplement is to do your research and visit popular forums. Ask users directly what brand they would recommend and see if the same brand keeps getting mentioned. I have two that I recommend below.

Can YK-11 be used in a bodybuilding setting where testing is regularly conducted?

There is no clear answer on this. YK-11 is a myostatin inhibitor so it doesn’t promote sex steroid hormone increases like an illegal steroid; however, some of its side effects are similar to that of a low-level prohormone. Even the most veteran users found in forums aren’t exactly sure.

If you personally have had experience with YK-11 and a bodybuilding drug test, please let me know in the comments below about what happened when you were tested. I’d love to hear from you.

You can check out the full list of banned supplements on the World Anti-Doping Agency website.

6.  How Does YK-11 Work?

How Does YK-11 Work

As I alluded to several times above, the way YK-11 works is through attaching itself to androgen receptors in the body. Once attached, it begins to promote the production of a compound called follistatin.

Follistatin is the worst nightmare of myostatin. Remember how myostatin suppresses muscle growth after you’ve reached a certain point? Well, follistatin puts myostatin back in its place, allowing your body to continue building lean muscle tissue.

7.  Side Effects of YK-11

Side Effects of YK-11
Source: sameer saeed

Most likely due to its infancy in the fitness industry as a muscle building compound, it’s not clear what side effects are to be expected with YK-11.

Those who falsely label it as a S.A.R.M. claim it has no side effects.

Those who say it’s a prohormone cite low-level prohormone side effects such as hair loss and acne as common side effects.

Finally, those who correctly announce it as a myostatin inhibitor are also on the fence. We know that YK-11 is pretty powerful stuff even though it’s not an anabolic steroid. Many reviewers compare it to being more anabolic than DHT (dihydrotestosterone) and some reviewers claim it has a methyl-ester attached to it.

For the sake of this review, I’ll write down the potential side effects that were most commonly cited in forums and reviews. Used correctly, YK-11 MAY promote the following side effects:

  • Acne
  • Hair loss
  • Low level liver toxicity
  • Slight increase in blood pressure

All of these potential side effects are easily remedied by using a post-cycle support supplement.

8.  What Does Science Say about YK-11

Since YK-11 is still in the spotlight of studies that are yet to be concluded, I’ll be basing this section off of the few studies that have been made available along with the general consensus of user reviews in the most popular bodybuilding forums.

Promotes Follistatin Production and Release

YK-11 Follistatin Production and Release

  • If there is one thing we can definitely say about YK-11 is that it’s serious when it comes to making sure follistatin gets sent to the front lines. Studies show that YK-11 is an effective way to increase the levels of follistatin in your body. Science also tells us that follistatin blocks the anabolic inhibiting effects of myostatin. (Source)

Promotes Lean Muscle Gains

YK-11 Lean Muscle Gains

  • Continuing with the idea above, since myostatin levels are pushed way down, your body is free to continue gaining lean muscle tissue. No, you won’t gain 20 pounds of muscle like you would with an anabolic steroid; however, your gains won’t be too shabby either. Many users claim that they have put on an additional 5 to 8 pounds of muscle mass with YK-11, which is incredible. Naturally, it might have taken that same user months or even a year to see those gains. (Source)

Anabolic Effects Protect Muscle

YK-11 Anabolic Effects Protect Muscle

  • If your goal is to get really lean, you always are at risk for muscle breakdown from things like a caloric deficit diet or extreme cardio. YK-11 is a protein sparing agent that also promotes lean tissue growth. What you essentially have then is a myostatin inhibitor that allows you to, at the very least, preserve the muscle you’ve built while you lean out.

Supports Hard Muscle Look

YK-11 Supports Hard Muscle Look

  • When you’re leaning out, the end goal is what is known as a hard muscle look. You see this look in fitness bodybuilding. It’s where there is a great deal of definition and the muscle looks flexed, even when it isn’t. Many users of YK-11 claim that it is an ideal muscle hardener. Combine that with its anabolic properties and you may have the perfect shredding supplement.

9.  Highlighted Benefits of YK-11

Highlighted Benefits of YK-11

  • Increase in follistatin levels
  • Blocks myostatin
  • Protects from muscle breakdown
  • Promotes lean size gains
  • Ideal for cut or mass gains
  • No water retention
  • Increase in muscular strength
  • Supports a fuller pump during workouts

10.  How to Use YK-11

How to Use YK-11

The dosage you’ll use will be dependent upon your fitness goals. If you’re trying to bulk up, you’ll use much more than if you’re trying to get lean and cut. Here’s a recommended cycle chart but be sure to check the label of the product as well. Dosages may vary from brand to brand.

Goal: Muscle Mass (Bulk)

  • Week 1: 5 mg
  • Week 2: 10 mg
  • Week 3: 15 mg
  • Week 4: 20 mg
  • Week 5: 25 mg
  • Week 6: 30 mg
  • Week 7: 30 mg
  • Week 8: 30 mg

Goal: Lean Muscle Mass (Cutting)

  • Week 1: 5 mg
  • Week 2: 5 mg
  • Week 3: 5 mg
  • Week 4: 10 mg
  • Week 5: 10 mg
  • Week 6: 10 mg
  • Week 7: 15 mg
  • Week 8: 15 mg

11.  Stacking Methods with YK-11

Stacking Methods with YK-11

Here is a recommended stacked cycle chart when you stack with Testolone, which is considered one of the best stackable compounds. Keep in mind that the stack below is for bulk muscle mass:

Week 1:

  • YK-11: 5 mg
  • Testolone: 5 mg

Week 2:

  • YK-11: 10 mg
  • Testolone: 5 mg

Week 3:

  • YK-11: 15 mg
  • Testolone: 10 mg

Week 4:

  • YK-11: 20 mg
  • Testolone: 10 mg

Week 5:

  • YK-11: 25 mg
  • Testolone: 10 mg

Week 6:

  • YK-11: 30 mg
  • Testolone: 15 mg

Week 7:

  • YK-11: 30 mg
  • Testolone: 15 mg

Week 8:

  • YK-11: 30 mg
  • Testolone: 15 mg

Popular Brands of YK-11

Popular Brands of YK-11

Here are the brands that users have reported to be of great quality:

12.  Conclusion

Whether you’re trying to get large or get lean, your body can only do so much. Once you reach your genetic limit, you’ll need something extra to push you to the next level. YK-11, a powerful myostatin inhibitor, may be exactly what you need when you want to level up.

Promoting the production of follistatin, YK-11 may be able to successfully block the muscle inhibitor known as myostatin. While it’s still a baby in the world of fitness research, few studies and many user reviews show great promise for this ingredient.

At the end of the day, it should pose no harm and taking it yourself and at least giving it a try has the potential to help you shed excess weight and replace it with lean muscle.

Have you used YK-11? Leave your review below!


  1. Kanno Y, Ota R, Someya K, Kusakabe T, Kato K, Inouye Y. Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression. Biol Pharm Bull. 2013;36(9):1460-5.
  2. Biol Pharm Bull. 2011;34(3):318-23.(17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11) is a partial agonist of the androgen receptor.Kanno Y, Hikosaka R, Zhang SY, Inoue Y, Nakahama T, Kato K, Yamaguchi A, Tominaga N, Kohra S, Arizono K, Inouye Y.

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Author: Rob Miller

Supplement Critique

Rob Miller founded SupplementCritique.com over 7 years ago, and has been the chief editor ever since. He has a diploma in Advanced Dietary Supplements Advisor, and worked at GNC for 3 years. He KNOWS supplements, both inside and out. Rob currently resides in Jupiter, FL, with his wife of 4 years.  Learn more about him in his Bio here. Follow him on Twitter , Facebook, LinkedIn, or find him on Google +.

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