The sex hormones are steroids and include testosterone, the primary anabolic steroid in humans. Anabolic steroids are tissue mass-increasing steroids, which means they help build muscle. The effect of anabolic steroids is to increase the body's ability to use protein to make muscle. The way your body uses protein can be affected by HIV infection. Anabolic steroids help send the amino acids back to the muscles.
Amino acids are the building blocks of proteins needed by the muscles to grow.
Testosterone is produced in the testicles and adrenal glands. Its function is to build muscles and masculinize. Naturally occurring testosterone is rapidly cleared by the liver and doesn't circulate in the body long enough to be useful as a treatment. Oral synthetic forms of testosterone are cleared more slowly by the liver , but tend to be liver toxic. Injectable testosterone formulations have longer half-lives than naturally occurring testosterone and are less liver toxic than the oral formulations.