YK-11 Mystery In a SARM World – Cycles, Stacks, Dosage and Side Effects

YK-11 is a mystery of the SARMs world. It has excellent muscle growth potential and mostly positive anecdotal reviews, but the research is extremely limited. So far, not even animal studies are available. What do we know by now and how to get extreme gains on pure mystique - read in this guide.


YK-11 is a novel performance enhancement compound, developed in 2011 in Japan. In medical terms, it’s everything – and nothing at the same time. So far, we have 3 main versions: 

  • YK-11 is a steroid because it has a DHT-based structure and resembles Testosterone by nature; 
  • YK-11 is a SARM because it selectively affects androgenic receptors, as it’s been proven in this study
  • YK-11 is a myostatin inhibitor because it… inhibits myostatin. 

These are 3 completely different classes of substances, with different purposes and abilities. So, is it a steroidal SARM? A steroid with a SARM-like mechanism of action? The best definition I can come up with is this: 

YK-11 is some serious transcendental shit. 

I don’t think the medical community will ever accept it on an international level, but at least it’s an honest one. The only thing we know is that it works and gives you both pros and cons of all three classes. 

How YK-11 Works 

As a SARM, it goes from your blood flow directly to the skeletal muscle (and bone tissue) and connects to the limited number of androgenic receptors in the cellular core. Since we have no official classification, every compound that acts selectively is a SARM, so technically, YK-11 is one of them. 

As a DHT-based compound, it partly reduces the aromatization (the conversion of Testosterone to Estrogen) and gives you muscle growth by enhanced protein synthesis. 

There are plenty of DHT-derivatives and SARMs around, and you probably know their primary functions. To refresh your memory on SARMs, you can check our guide on the class. I believe that the myostatin inhibition part is the most powerful of YK-11 abilities and the one that has at least a little research behind it, so I’ll give it more time here. We’ll start with the basics. 

What Is Myostatin 

Myostatin is a regulatory protein. It has just one purpose in your body – to limit the amount of muscle you can grow. While for most people, it’s insurance from disease-driven muscle hypertrophy, for athletes – it’s a cruel mistress. Myostatin doesn’t give a shit about all your daily sacrifices, all your motivation, and blood-boiling workouts that drain you out. It slaps a limit on your growth, and that’s it. You can’t order it to get away, and it does not give you any credit. 

What Is Follistatin 

Follistatin is just another natural substance (even though you can buy it in a pure form, as Follistatin-344). It has a vast spectrum of properties, but the one that matters most for athletes – is the ability to inhibit myostatin. 

To put it simply, Follistatin – is a thing that combats another thing that doesn’t let your muscle grow. 

YK-11 makes your body produce more Follistatin, and therefore – gives you almost unlimited muscle growth.

YK-11 Benefits 

So, why all the uncertainty is worth the risk? The answer is simple: 

YK-11 is potentially the most powerful compound of its kind on the market, both for synergy and solo. 

I say «potentially» because we have no direct numbers yet. It hasn’t been around long enough to say clearly, but the mechanism of action is promising. These are the benefits we know you can expect: 

Muscle Growth

This time, I won’t give you any suggestions, expectations, or anecdotal experience. This time – just Look. At. This. Fucking. Mouse. 

Here I obviously want the mouse picture from this study (https://pubmed.ncbi.nlm.nih.gov/11459935/)

The poor thing is not directly on YK-11, but oh God, it’s bulked. 

The study covered the effects of Myostatin inhibition by the Follistatin production boost. That’s exactly what YK-11 does. The mouse got 4 times bigger, and as if you didn’t know. 400% mass gain is just crazy. 

Of course, this example doesn’t mean that you will be THAT massive in just one cycle of YK-11. It shows you what «unlimited muscle growth» looks like. Your individual result with YK-11 depends on multiple factors: 

  • Genetics;
  • Pre-existing stats; 
  • Experience with gear; 
  • Age; 
  • Diet. 

Anecdotally, in a solo cycle, YK-11 is more potent than Ligandrol (LGD-4033) or MK-677 (aka Ibutamoren, a growth hormone booster). In a stack with anabolic steroids, the limits are yet to be found. 

Strength Gains 

When you get the volume, you get the functional boost as well. That’s the effect that athletes mention most frequently. YK-11 is more potent than other SARMs in terms of strength boost, BUT it’s not a heavyweight lifter’s dream. It seems to be weaker than most anabolic steroids – especially on mild doses. If your target is to get the strength through the roof – either take pure anabolic steroids (say, Deca) or YK-11 with a slightly bigger-than-usual dose, say, 10-12mg ED. 

Sex Life Improvement 

Thank the DHT base for this one – all dihydrotestosterone-derived compounds are powerful androgens, and all of them make you a monster in bed. Not the Godzilla type, though – you’re not going to sleep for ages and destroy everything on your way when you’ll wake up. More like a King Kong. You’ll want to steal your woman from whatever skyscraper she works at, take her to your cave in the jungle, and don’t leave the place for a week or two. No army and no airforce will stop you from enjoying the sex marathon of your life. 

Bones Strengthening 

The selective nature of YK-11 means that it connects to receptors in just two types of tissue: skeletal muscle and bones. I can’t say that it’s the best osteoporosis treatment you can find, but the positive effect is clearly there. 

How To Take YK-11

Like other SARMs, YK-11 is oral. You can get it either in a pill form or as a liquid – in drops. Both have excellent bioavailability, but I’d recommend the liquid form. Pills are mostly dosed 10mg each, and if you plan to break your daily dose in more than two parts – it’ll be quite hard. 

YK-11 Dosage 

First of all, these are just recommendations. We don’t have any official data and can rely only on anecdotal experience. 

YK-11 seems to shine best in doses between 5 and 15mg.

Take less, and it’s just useless. Anything extra, and you get more side effects than benefits. Most athletes just take one pill (10mg) a day, but I’d recommend to break it at least in two equal parts, to smooth the effect. 

YK-11 Solo Cycle

First of all, you should know that YK-11 is suppressive. You will need PCT after the cycle, and your Testosterone will undoubtedly go down. Most athletes run YK-11 with a Testosterone base – to keep the Testosterone levels high enough and then hop on the traditional PCT cycle. 

With all the caution taken to account, anecdotally, YK-11 is MILDLY suppressive, so you can run it solo (with a blood work control, of course). Here is how the cycle should look like: 

WeekYK-11Nolvadex PCT
7-820mg ED

YK-11 Stacks 

That’s where it shines best. You can add YK-11 in a mild dose to any of your favorite bulkers and enjoy the boosted effect. Here is a classic Testosterone Enanthate cycle with YK-11 and do not forget about Nolvadex

WeekYK-11Testosterone EnanthateNolvadex PCT
1-610-15mg300-500mg EW
7-8300-500mg EW
11-1220-40mg ED

I limit the thing to just 6 weeks because we don’t know how it acts in the long run. We don’t even have enough anecdotal data, so it’s better to avoid it and wait for others to do the experiments. 

YK-11 Side Effects 

As I mentioned in the beginning, you can expect the drawbacks of all 3 main gear groups. See for yourself: 


As a steroidal compound, YK-11 DOES suppress your natural Testosterone. The Testosterone shut down is rare but possible. You should not even think about running the compound without a proper post-cycle therapy of Nolvadex or Clomid. Here you can read a more detailed guide on them. 

Liver Damage 

YK-11 is oral, but it’s not 17-alpha-alkylated. Instead, a methyl group was added to the structure. Methylated compounds ARE liver toxic as well, so you should keep your diet reasonable and take some hepatoprotectors. Avoid all the junk food to minimize the pressure on your liver. At the beginning of the cycle and right after it, a couple of tests would be nice as well. 

Mental Side Effects 

As a DHT-based compound, YK-11 affects your central nervous system. The practical outcome depends on your pre-existing stats. If you’re a relatively calm guy, you are more likely to develop depression and low stamina issues. If you’re a short-tempered person, brace yourself and put extra effort into anger management – YK-11 can give you increased aggression and easier irritability. 

So far, seems like the gear is mostly safe? Even though it’s mostly true, that’s clearly not all sie effects. 

Other YK-11 Side Effects

Another list I can legitimately put here looks like this: 

  • Whatever;
  • God;
  • Has;
  • Prepared;
  • For;
  • You; 
  • Buddy. 

And I’m deadly serious. The clinical data we have on YK-11 is so insufficient that all we know is practically based on anecdotal experience. YK-11 was first described just in 2011. One of the long-term side effects can be «your dickhead develops a tiny Steve Buscemi face on it», and we still have no chance to prove or bust it. 

The Market Problem With YK-11 

Fake YK-11, fake YK-11 is everywhere. It’s new, it’s hot, everyone seems to start talking about it, so greedy fucks will definitely try to sell you the name and not the substance. YK-11 formula is so complicated and challenging to recreate that any cheap YK-11 is pure bullshit by definition. It is practically impossible. 

Even a brief look at the full name of the compound gives you a clear understanding, that it’s not the kind of gear that a bunch of university dropouts can synthesise in the basement:

(17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester.

Don’t bite on any sketchy deals, avoid new sources, and skip all «sales». It might work with some old and mass-produced compounds, but never – with a new and experimental one. 

Personal Opinion on YK-11

I have an unpopular opinion on the YK-11 nature «problem»: it does not matter at all. If you’re not a scientist, you can avoid all the buzz around the compound’s nature. SARM, steroid, or whatever else Web experts come up with, has no sense Dealing with a poorly research compound like this, take it like the most dangerous stuff you can ever find. Treat it as the most suppressive anabolic steroid, the most unpredictable SARM, and veterinary-only myostatin inhibitor, combined. 

You have no other option but to be a researcher yourself. Go for weekly blood works. Make this cycle the most accurate and «aware» one of your life. Approach the problem scientifically, but not like a lab rat. No «Ok, what if I take 10 times more this time», no «What will happen if I skip on the PCT», and definitely – no «Hey, maybe it’s the first steroidal compound that works great with alcohol?». 

Find that thin line between experimenting on yourself and looking for the personal sweet spot. It’s thin as fuck, I know. However, that’s the only way you can get all the benefits of YK-11 safely. Otherwise, if you want things to be less adventurous and more predictable, stay away from the thing. YK-11 is the Age of Discovery stuff of modern bodybuilding. You either find new land to give it your name, or a cannibal tribe grills your ass alive. No way to know for sure – and that’s the spirit.