A number of medical reviews have cited its outstanding potential
to promote muscle gains as well as fat loss and weight loss.

There have been an increasing number of American bodybuilders that are experimenting with this drug.
Many athletes who use Clenbuterol claim that it promotes dramatic strength increases and a very noticeable reduction in body fat and weight loss.

How it works

Some athletes claim that they enjoyed significant gains in muscle mass while using clenbuterol. Clenbuterol’s most valid application seems to be as a pre-contest, cutting drug. It is not banned by any athletic committee; thus, numerous professional bodybuilders have used it for the last month of contest preparation. Cycles range from 6-12 weeks in length. Side effects include nervousness, tremors of the hands, headaches, and insomnia. The reason although it is fairly anabolic, and it promotes the burning of fatty acids through brown fat burning.

Dosages

Dosages are normally between 20-120 mcg for bodybuilders that use this.This drug becomes ineffective for its anabolic properties after 18 successive days of use. Brown fat-burning and Weight Loss, will continue past the 18 day period. After 12 weeks, the drug should be discontinued for a couple of months.

Clenbuterol (often called just “Clen”) is used by athletes and bodybuilders for it’s ability as a beta-2 agonist. It therefore stimulates your beta-2 receptors, which in turn help you to lose fat by allowing your body to release and burn more stored fat. Clen has been used for literally decades in the foreign veterinary world, for increasing the lean yield of livestock. It is clearly a very effective agent for this purpose, although its long half life and tendency to stay active in the body for long periods of time mean that vets in the United States aren’t able to use it. This is also the reason why (although it’s an asthma medication) it’s not available to asthmatics in the US of A. Albuterol is Clen’s shorter acting cousin, and that’s the FDA’s drug of choice here. But in the world of athletics, Clenbuterol has a much longer history of use.

Specifically, it’s used for fat loss, and since we’re talking about fat loss here, and this purpose is what it’s most often used for by athletes. Briefly stated, Clen is used as a repartitioning agent, and what this means is simply that it will increase your ratio of Fat Free Mass (FFM) to Fat Mass (FM) (1). When you use Clen, besides (of course) noticing some fat loss, you’ll feel your body temperature rise a bit, and your appetite will be slightly repressed. (2)

Anyway, as you may have guessed, because the FDA doesn’t allow Clenbuterol use in asthmatics, and the USDA doesn’t allow it in livestock, there aren’t a lot of human studies to really examine with regards to Clenbuterol. Unfortunately this makes research a bit difficult, as it’s well known that animals have a some important differences in their beta-receptor type and concentrations, but animal studies are still quite useful here.

Clen is quite anti-catabolic and/or anabolic in almost every (animal) study ever done on it, although this hasn’t been studied or confirmed in human studies (3). Also, a trend we see with Clenbuterol administration in animals is that the doses used are very high- more than anyone I’ve ever heard of actually taking. So, what I’m saying is that if Clenbuterol is anabolic or anti-catabolic in humans, only mild anabolic or anti-catabolic effects can realistically be expected. We can take a look at horses given a human-like dose of clen (slightly over 1mcg/lb x2 a day) and exercised for nearly human-like times (20mins, 3x a week) showed very significant decreases in %fat (-17.6%) and fat mass (-19.5%). Interestingly, this significantly increased (+4.4%) at week 6 (1). This has been one of the reasons I have never believed in the 2 weeks on and 2 weeks theory of Clenbuterol administration. Why wouldn’t we want to use it for at least 6 weeks, considering the fact that it seems to have some profound effects during later administration. A “second wind” so to speak (get it? “second wind”? it’s an asthma med! Ha! Ok…moving along…).

One of the primary drawbacks of Clen is that after a couple of weeks, it seems to stop working for most people. This is because it can cause a downregulation of pulmonary, cardiac and central nervous system beta-adrenergic receptors(4). This is why it seems to stop burning fat for most people at that point. To counteract this, you can take some Ketotifen, Benadryl, or Periactim every 3rd or 4th week that you remain on clen. These are prescription anti-histimines, so they’ll make you drowsy (take before bedtime).

Also, bear in mind that clen isn’t great for your heart, and can cause some issues there (enlargement of ventricles, etc…) but most studies showing Clen to cause heart problems are with animals, and even though the dosing is almost similar to what humans take (in some studies its within range of what would be double of a large human dose…). Again, it’s important to remember that animals have more beta-2 receptors and they cause certain event chains that humans’ beta-2 receptors may not, due to their relatively high concentrations. Clen causes cardiac hypertrophy to some degree, in some cases and even dose-dependent apoptotic and necrotic myocyte death (5). And since Clen depletes taurine (6) as do most if not all beta-agonists, you may want to supplement your Clen use with some Taurine.

One of the weirdest things about Clenbuterol is that even though it’s an asthma medication, studies have shown reduced exercise (cardiovascular) performance with Clen (7), but some also show that Clen can alleviate exercise induced asthma (8)!

Clen is one of the easiest drugs to find proper dosing for, and I’ve always made the same recommendations as to finding the appropriate dose for you. Basically, start with 20mcgs upon rising. If the side effects (possible anxiety, and shaking or sweating) aren’t too pronounced, then repeat that same dose again later in the day, and then once again in that day (again, if you find you can tolerate the effects). If you start experiencing intolerable sides, then decrease the does to where it’s tolerable. If not, then start increasing the dose more, very gradually.

Don’t go over 200mcgs, though…and keep your Blood Pressure at (or under) 140/90. If your Blood Pressure goes over that, reduce your dose. If side effects are intolerable, decrease your dose.

References:

1. J Appl Physiol. 2001 Nov;91(5):2064-70

2. Int J Obes Relat Metab Disord. 1994 Jun;18(6):429-33

3. Ann Pharmacother. 1995 Jan;29(1):75-7

4. J Anim Physiol Anim Nutr (Berl). 2004 Apr;88(3-4):94-100

5. Muscle Nerve. 2005 Dec;32(6):767-74

6. Adv Exp Med Biol. 1996;403:233-45

7. Med Sci Sports Exerc. 2002 Dec;34(12):1976-85

8. Respiration. 1987;51(3):205-13