How Clenbuterol Works
 
Clenbuterol, nicknamed "clen," is the generic term for a nonsteroidal drug that was originally designed as a bronchodilator, used to treat chronic breathing disorders like asthma and obstructive pulmonary disease. However, given its powerful fat-burning properties, clenbuterol is also used by bodybuilders and professional athletes as a stimulant and/or weight loss drug.
Most commonly available in its salt form, clenbuterol hydrochloride, and sold under the trade names Dilaterol, Spiropent, Ventipulmin, this drug acts as a beta-2 adrenergic receptor agonist, meaning it stimulates beta-2 receptors. Clenbuterol also relaxes smooth muscles that line airways and helps them dilate (expand) to increase the amount of oxygen people and animals receive from each breath.
Aside from helping clear airways, other effects created by clenbuterol closely mimic adrenaline, a substance that's released in the body when one is feeling strong emotions like excitement or fear. But unlike adrenaline, which causes a multitude of physiologic reactions, clenbuterol is far more selective and mainly interacts with the beta-2 receptor.
This selectivity enables clen to produce specific adrenaline-like effects such as increasing core body temperature and raising metabolic rate, without also increasing heart rate by a substantial amount. Clenbuterol's stimulation of the beta-2 receptors causes the cells' mitochondria to heat up and produce more heat, thereby creating a thermogenic effect where more calories are burned, fat cells are stimulated and weight loss is more likely.
Beyond simple weight loss, clenbuterol leads the body to favor using stored body fat for energy over body protein. A 1987 study performed on rats concluded that the ratio of body protein to fat after clenbuterol treatment increased by over 50% in both normal and protein-deficient rats.
Obviously its ability to preserve muscle mass while burning fat makes clen a highly sought-after drug among bodybuilders. But it is also used by celebrities and the general population as well. So for anybody who's interested in this drug, let's move on to discussing clenbuterol's benefits, side effects, usage, dosage, comparisons to ephedrine and legality.
 
What are the Benefits of Clen?
 
The most-popular off-label use for clenbuterol is definitely weight loss. However, there are plenty of other benefits that clen can provide for humans and animals. But as you'll see below, humans and animals can experience different results (notably in building muscle) from taking this drug.
Appetite Suppression
While clenbuterol is often identified as a weight-loss drug, one of its lesser-known benefits involves appetite suppression. Research from 1994 concluded that clenbuterol's beta-2 stimulation has an effect on regulating feeding behavior.
Body Recomposition
Research has shown that clenbuterol can aid in animals' body recomposition, which is the process of simultaneously burning fat and building muscle. This is a difficult process because it requires precise caloric intake while burning enough calories through workouts. But a 1985 study involving Standardbred mares showed that clenbuterol usage can result in significant body repartitioning. After two weeks of being administered clen and undergoing regular exercise, the mares experienced a 15.4% drop in body fat percentage coupled with a 4.3% increase in fat-free mass.
Reducing Exercise-induced Asthma
Given its use as a bronchodilator for treating chronic breathing diseases, it only seems natural that clenbuterol would help reduce exercise-induced asthma. And a 1987 study confirmed this by revealing that clen protects against exercise-induced asthma without causing negative effects on the cardiovascular system (4). However, despite popular belief, this drug does not enhance cardiovascular efficiency in healthy individuals; in fact, a 1987 study showed that clenbuterol can reduce endurance and exercise duration.
Muscle Building
Clenbuterol has been shown to have a positive anabolic effect in various species of animals. For example, clen increased the size of skeletal muscle fiber in rats in utero. Another study involving rats on a protein-restricted diet revealed that clenbuterol can hasten the recovery of muscle mass following malnutrition. There has yet to be any published research that links clenbuterol to being directly responsible for muscle enlargement in healthy humans. However, human studies do suggest that long-acting systemic beta 2-agonists can increase muscle size in specific muscle fibers. But this long-term effect may be so gradual that it goes unnoticed in healthy users.
Weight Loss
This drug can help provide dramatic weight-loss results in a short period of time. Unfortunately, there is a severe lack of human research in the scientific community regarding clenbuterol weight-loss effects. But there are numerous clenbuterol reviews across the internet that boast of this drug's notable fat-burning capabilities. Animal studies, such as the previously mentioned one involving mares, offer concrete proof that clenbuterol results include significant fat loss. Research performed on rabbits provides more evidence that clen can reduce body fat percentage in animals.