YK-11: Is it a powerful SARM or a steroid?

YK-11 is it a SARM or steroid

YK-11 is an unusual SARM (Selective Androgen Receptor Modulator).  YK11 was created in 2011 by Japanese researcher Yuichiro Kanno, by directly altering the chemical structure of DHT (a hormone that occurs naturally in the body) – a stronger form of testosterone.

Although it is commonly grouped with SARMs due to its ability to selectively bind to androgen receptors in muscle and bone tissue, YK11’s chemical structure and mode of action set it apart from traditional SARMs such as MK-2866, LGD-4033 and RAD-140.

YK-11 is believed to act as a partial agonist of the androgen receptor, leading to increased anabolic activity in muscle and bone tissue. Additionally, YK-11 has been found to inhibit the production of myostatin. Myostatin is a protein that basically limits the amount of muscle growth. By lowering the amount of myostatin, muscle growth is enhanced.

So, besides being a steroidal SARM, YK-11 myostatin inhibitor.

YK-11 molecular structure

Benefits of YK-11

While research on YK-11 is limited, there is a fair amount of anecdotal evidence and user reports. Based on this information, we know that the main benefits of YK11 include increased muscle growth, enhanced fat loss, improved bone health and faster recovery.

Increased Muscle Growth

YK-11’s primary draw for bodybuilders and athletes is its potential to promote muscle growth. By binding to androgen receptors and inhibiting myostatin, YK-11 creates an anabolic environment that encourages the development of lean muscle mass. Users of YK-11 report significant gains in muscle size and strength, although more research is needed to confirm these anecdotal claims.

Enhanced Fat Loss

Like other SARMs, YK-11 has a positive impact on body composition by promoting fat loss. By increasing lean muscle mass, YK-11 can indirectly boost metabolism, leading to a more efficient calorie-burning process and thus promoting fat loss.

Improved Bone Health

YK-11’s ability to bind to androgen receptors in bone tissue will probably lead to improved bone health by increasing bone mineral density and promoting bone turnover. This can be particularly beneficial for athletes and older individuals who are at risk of developing osteoporosis and other bone-related disorders.

Faster Recovery

By stimulating muscle growth and inhibiting myostatin, YK 11 may also contribute to faster recovery times following workouts. Enhanced recovery can allow for more intense and frequent training sessions, ultimately leading to improved performance and progress.

Side Effects of YK-11

As with any compound, YK-11 may cause side effects in some users. It’s essential to be aware of these potential side effects and monitor your body’s response to YK-11 closely. Some common side effects include:

Testosterone Suppression

Although YK-11 is believed to have a selective effect on androgen receptors, it may still lead to testosterone suppression in some users. This can result in symptoms such as fatigue, decreased libido, and mood swings. To counteract these side effects, many users opt for a post-cycle therapy (PCT) after completing a YK-11 cycle.

Liver Toxicity

There is some concern that YK-11 may be liver toxic due to its steroidal structure. While definitive research on this topic is lacking, it’s essential to monitor liver enzyme levels and consider using liver support supplements when using YK-11.

Hair loss

Some users have reported hair loss while using YK-11. This side effect may be due to YK-11’s interaction with androgen receptors in the scalp. It’s important to note that hair loss is not a guaranteed side effect, and individual responses can vary. If you are predisposed to male pattern baldness, you may want to proceed with caution when considering YK-11.

YK 11 before and after

If you google for “YK-11 before and after reddit” you will find a lot of information about the results that users had from a cycle of YK-11. There is no shortage of “before and after” pictures on the internet, but most of them are not genuine.

We will give 2 examples of YK 11 results that we have personally been able to verify.

Example 1

Subject: 34 year old male with 2 years of experiences weight-lifting

Cycle: 10mg of YK-11 for 8 weeks, followed by a 4 week PCT (Nolvadex)

Results: Muscle mass increased by 4KG, strength increased by 10%, fat decreased by 1KG

Example 2

Subject: 33 year old male with 4 years experience weight lifting

Cycle: 15mg of YK-11 for 6 weeks, followed by a 4 week PCT (Clomid)

Results: Muscle mass increased by 5KG, strength increased by 15%

YK-11 dosage and cycle length

There is limited research on the optimal dosage and cycle length for YK-11, so most recommendations are based on anecdotal reports. A common starting dose for YK-11 is 5 mg per day, with some users increasing the dosage to 10-15 mg per day after assessing their tolerance.


Because YK 11 has a relatively short half-life of 12 hours, it is recommended to divide the dose. For instance, if you want to take 10mg per day, it is advised to take 5mg in the morning and 5mg in the evening.

Cycle length

Cycle lengths typically range from 4 to 8 weeks, with a PCT recommended after completion to help restore natural testosterone production.

YK 11Nolvadex (PCT)
Week 1 – 810mg per day/
Week 9 – 10/40mg per day
Week 11 – 12/20mg per day

Stacking with other SARMs

Because YK 11 is an exceptionally strong SARM, we don’t advice to stack it with other SARMs, as doing so does not lead to increased benefits, but may increase unwanted side effects.

However, it is possible to stack YK11 with other compounds such as MK-677 or Cardarine. Unlike SARMs, these compounds do not bind to the androgen receptor, but work in a completely different way.

Is YK-11 legal

The legal status of YK 11 is the same as that of other SARMs. This means that they are legal when sold as a research chemical, but not as a supplement. The only exception to this rule is Australia, where YK-11 is a schedule 4 prescription only compound by the TGA.

Use in sports

Almost all sports bodies, including the Olympics, listed YK11 as a prohibited substance because of the unfair advantages that it gives (increased muscle mass, strength, etc.). It’s listed as a banned substance by the WADA (World Anti Doping Agency) and the USADA (the United States Anti Doping Agency).

YK 11 VS RAD 140

As the title as this post already revealed, YK 11 is more than just a SARM. The steroidal structure and the fact that it acts as a myostatin inhibitor makes this SARM unique.

But how does it compare to the strongest non-steroidal SARM: RAD 140 (Testolone). We will provide a comparison based on several aspects.


When we look at the half-life of these two SARMs, RAD 140 vastly outperforms YK 11.

The YK 11 half-life is just 12 hours, which means that it has to be taken twice a day to get the full benefits.

In contrast, RAD 140 has a half-life of 44 hours, so you only have to take it once a day or even once every other day to stabilize blood concentration level.


If we look at the results in terms of strength and muscle mass, YK 11 is without a doubt the stronger of these two SARMs.

However, if we focus on fat loss and vascularity, RAD 140 is the superior one.

Side effects

Where it concerns side effects, the most powerful compound usually has the most of them. And when comparing YK 11 with RAD 140 this is holds true:

  • YK 11 is more suppressive than RAD 140, which shouldn’t come as a surprise given the steroidal nature of this SARM.
  • Because YK 11 has a methylated group added to it, it puts more strain on the liver. With this compound, it doesn’t hurt to take some liver support such as Milk Thistle during the cycle.

Frequently asked questions

Is YK-11 legal?

At this moment, YK 11 is legal in almost every country around the world, with the exception of Australia. However, as it is not approved for human consumption, it cannot be sold as a supplement in most countries. But it can be sold for research purposes.

What is the half-life of YK-11?

The half-life of this steroidal SARM is roughly 12 hours. Therefore, it is common to divide the dosage in 2.

Is YK-11 the strongest SARM?

YK-11 is easily the most potent SARM on the market. It is also the only SARM that has a steroidal structure.

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