Mesterolone, marketed as Proviron, is an androgenic-anabolic steroid derived from dihydrotestosterone (DHT). While its primary medical use is for testosterone replacement therapy in men with low testosterone levels, it is sometimes used off-label by bodybuilders and athletes for its potential muscle-enhancing effects.
- Androgenic Effects: Mesterolone has mild androgenic properties, which may contribute to increased muscle hardness and a more defined appearance. It may help reduce water retention and promote a leaner physique.
- Estrogen Control: Mesterolone has the ability to bind to estrogen receptors, although it does not aromatize (convert) into estrogen. By occupying estrogen receptors, it may prevent the binding of estrogen and help mitigate estrogen-related side effects such as water retention and gynecomastia.
- Free Testosterone Enhancement: Mesterolone has been shown to bind to sex hormone-binding globulin (SHBG), a protein that binds to testosterone, rendering it inactive. By binding to SHBG, mesterolone can potentially increase levels of free testosterone in the body. Free testosterone is the active form of the hormone and is associated with muscle growth and development.