Clenbuterol and Muscle Growth

Clenbuterol and Legal Steroid Clenbuterall

I still remember when Clenbuterol was the new wonder drug.

“You know, my rat seems to respond very well to this new stuff.”

“Oh, which one?”

“You know this new stuff, Cle something.”

“Clenerol, … no, Clenbuterol. I don’t know why I cannot remember that name”

The friend talking to me was in the habit of trying each new drug or new stack on a rat that he would buy for the occasion, as an experiment before he tried the substances himself. I guess it was his way of being careful.

Clenbuterol (Clen) was supposed to be an incredibly anabolic, non-hormonal compound. Furthermore, it could destroy fat like nothing else. A new category of drugs had just emerged: the repartitioning agents. What a brilliant concept! We could replace fat by muscles after all!Now, more than 10 years later, while Clenbuterol has not lived up to initial expectations, it is still used extensively in bodybuilding circles. Why? I think it’s time for a review in depth of this drug’s properties and effects. What I am going to reveal, very strange. Based on the fact that kilos of this stuff swallowed voraciously or injected by eager bodybuilders (not all at once, of course).

Is Clenbuterol a non-hormonal drug?

Clenbuterol:  a repartitioning agent, not a hormone. I guess the idea came from the fact, not a steroid and not related to testosterone in any way. Many drug free bodybuilders bought that idea and started using drugs with the help or because of Clenbuterol. Clenbuterol, indeed very closely related to hormones called catecholamines. The best known catecholamines are adrenaline and noradrenaline (a.k.a epinephrine and norepinephrine). So, taking Clenbuterol is a bit like using those hormones except that Clen acts mostly on beta adrenergic receptors and not on alpha adrenergic receptors. Adrenaline and noradrenaline act on both kinds of adrenoceptors. Clen is therefore a beta agonist (beta 2 to be more specific).

Is Clenbuterol anabolic?

The popularity of Clenbuterol came from the amazing muscle building action experienced on some animals. Clen has the ability to quickly and strongly stimulate the muscle protein synthesis processes. It is more potent even than anabolic steroids. Our high hopes with Clen rapidly faded away. Replaced by deep disappointment. We all hoped that something with, less side effects could have replaced the anabolic steroids. Also, Clen arrived when drug testing began to be implemented in bodybuilding. It seemed that a good way to beat the test was to use this magical Clen (it was not yet on the doping list). It is sad but true: Clen has a very low muscle building capacity in humans. Why? And if so why is it still popular? Unfortunately, Clen is banned. However, many legal steroids work exactly like Clen works. Read on for how Clen works.

Does Clen act on beta 2 receptors?

If Clen is a true beta 2 receptor agonist, there is no reason for it not to be anabolic. Human muscles are full of beta 2 receptors ready to react under the order of Clenbuterol. Intense exercise can increase the beta 2 receptor density in muscles, creating a potential synergy. This would mean that training should increase the muscle sensitivity to Clen. The problem, such results not observed, even in animals. In fact, animals given Clenbuterol and then intensively trained show very poor results.

Later researchers demonstrated that the muscle building properties of Clen were not derived from a specific activation of beta 2 adrenoceptors as previously thought. Rather, Clen acts on a still unidentified atypical beta receptor. Then, it was thought that Clen would act on the newly discovered beta 3 receptors. Next, action on beta 4 was hypothesized. Both proved to be wrong as far as anabolism is concerned. In order to explain the lack of effect of Clen on anabolism in humans I think it is safe to conclude that we do not possess a significant amount of those atypical beta receptors in our muscles.

Of course, animal studies were performed with huge dosages starting with a rough equivalent of 50-60 tablets of 20 mcg a day. But even in increasing the dosages close to unsafe amounts (using a beta 1 receptor antagonist to minimize the side effects of Clen on the heart), no one ever experienced the strong anabolic action of Clen. And this is not due to a lack of candidates willing to try. We should congratulate those kamikazes as it is thanks to them that major muscle building breakthroughs are revealed.

Some human studies have shown a mild and transient anabolic action of catecholamines. Eating proteins do that too, but believe me it is not with this sort of mild anabolic effect that your muscles are going to be visibly bigger.

Is Clen anti-catabolic?

Controversy still remains as to the capacity of Clen to mediate muscle growth, because of a strong anabolic or a potent anti-catabolic action. If Clen is not anabolic in humans, is it at least anti-catabolic? The answer is yes and no. Let me explain: if you are eating normally, I doubt that Clen exerts any significant anti-catabolic action. In fact, Clen is probably more catabolic than anti-catabolic at high dosages. However, when you’re on a low calorie diet, things are very different, and Clen is then truly an anti-catabolic drug. It may sound paradoxical but it is not at all.

When on a restrictive diet, the main problem for our body is to use the fat from the adipose tissue as energy in order to make up for the caloric deficit. In bodybuilders, this pathway is very inefficient. We eat a high carb diet all year long, which means we train our body to selectively use carbs at the expense of fat. On a diet, our body has not been trained to use fat instead of carbs. It is still good at using carbs and bad at burning fat. So, instead of using fat as energy our body uses a second best source of energy: proteins. And where are those proteins coming from, from our muscles, which are perceived as a protein reserve while we are on a diet. Our muscles shrink while fat remains stuck.

How Clen Works

This is where Clen comes in. Clen is able to help our body uses its own fat as energy instead of muscle proteins. The fat burning process is accelerated which mechanically spares our muscles mass. At the end of the diet, thanks to a quicker and more efficient fat usage, we end up leaner and bigger. Not bigger compared to what we were before the diet but bigger compared to what we would have been at the end of the same diet without the Clen.

Depending on the length and the severity of the diet, but Clen can make a difference of several kilograms, which is remarkable. Growth Hormone is popular before a competition for the very same reason: it renders the diet both easier and far more effective, preventing excessive muscle shrinkage. For those who still insist that it is possible to diet without sacrificing a significant amount of muscle mass, please take a long look at Dorian Yates’ book “Blood and Guts”. Before and after pictures shown while on a diet. An expert eye sees that many pounds of pure beef, lost while the amount of fat he got rid, limited. This is what happens when you get shredded, even if you’re the best in the world (Of course, by diet I don’t mean shedding five pounds before the holidays. I mean a real, shredding diet).

Please understand that this anti-catabolic action of Clen is indirect and will therefore not help you get bigger while you are NOT on a diet. This is why I say Clen can exert some anti-catabolic action or none at all.

Is Clen catabolic? Can this actually help us grow?

This may sound even stranger after what I just said but Clen can truly be a catabolic drug, too. At low dosage, it will go unnoticed. But past a certain amount (equivalent of 15-20 tablets of 20 mcg) chances are you are going to get sore by using Clen. Scientific research in humans demonstrates a potent catabolic effect of Clen as reflected by a rise of serum creatine kinase level. This means that Clen is attacking our muscle cells a bit like heavy training does.

Sound bad?


Is it of any use for bodybuilders? Yes!

For “drug free” bodybuilders, it means that you have got to stay away from this high dosage of Clen. On the other hand, for steroid users, it is unfortunately a very interesting property. Ten years ago, I would not have made such a statement. Almost all the anabolic steroids were still available and one could choose the ones that suited him best. Saying that such a choice does not exist anymore would be an understatement. Prices and availability are inversely progressing. Testosterone is again the steroid of choice (because of a lack of choice). The main problem with testosterone is that after a while a user experiences more and more trouble getting sore while on it. Of course, it depends on the dosage and the capacity of the user to transform the male hormone into female hormones (aromatization).

You see, estrogens protect our muscles from damage. This is good in every sport except bodybuilding. Potent anti-aromatase drugs do exist but their prices prohibit their use. Tamoxifen (Nolvadex) will exert an estrogen-like activity on muscle (and fat too) in many people, which is going to reduce their capacity for muscle growth while helping them to get fat.


Why do we want some muscle damage to occur because of training, simply, because our muscle cells are internally able to manufacture very potent growth factors such as IGF, FGF, Prostaglandins and probably GH too, in case of damage. The more steroids one uses, the higher this manufacturing capacity should be. Furthermore, steroids increase the muscle’s sensitivity to the anabolic actions of those growth factors. This is a shame, since most of those growth factors released (and therefore become active) if the muscle membrane experiences some damage. Training acts like a robber who opens the vault, growth factors,l hidden. Because of the estrogens, this beneficial effect of training attenuated. Clen can act like this robber to unleash the growth factors. How do we manage this?

Once all the growth factors  released, growth takes place, repairing the damage and inducing a hypertrophic response on top of this. On the other hand, the muscle capacities to reproduce extra amounts of growth factors  impaire for a short while. Steroids will accelerate recovery from this shortage.


But it means that the high doses of Clen used sporadically. I would say about once a week.  Coupled with a traumatic workout on a body part where you want to accelerate growth. You also need to rotate those body parts. Making sure the restoration of the manufacturing capacities in one muscle is complete before triggering a new release. For example, one week you can train your back in a traumatic fashion (using heavy weights along with forced and negative reps in movements that end with a strong stretch). Next week, do the legs. The following week, it can be chest.

Pain due to the soreness,  rewarded by rapid growth. Therefore, the catabolic actions of Clen  trigger growth, but only in synergy with steroids. If you follow this procedure, make sure you use massive amounts of proteins and amino acids, especially BCAA and taurine.  Clen accelerates their destruction and you do not want to experience a shortage in either one.