Clenbuterol is used to treat asthma and is very popular with bodybuilders because it increases muscle growth and cuts fat. It is a beta-2 agonist, which means that it has effects similar to the fight-or-flight hormone adrenaline. It is a popular drug with bodybuilders because it increases muscle mass, cuts fat and boosts energy levels. It builds muscle by promoting specific signaling pathways inside the cells that activate protein synthesis and modifies muscle protein breakdown, remodeling, and repair. It decreases body fat by binding with the adrenaline receptors in fat cells, which promotes fat breakdown and release.
Italian researchers found that clenbuterol reacts with nitrites in the gut and forms compounds that could cause cancer. Also, studies in humans and animals showed that clenbuterol caused severe cardiovascular side effects, including heart failure. Clenbuterol builds muscle, but the side effects are potentially dangerous, so bodybuilders should use it with care. However the studies regarding the role of clenbuterol in preventing several forms of cancer are still at incipient level and will be widely researches in the next years.