Proviron has four distinct uses in the world of bodybuilding. The first being the result of its structure. It is 5-alpha reduced and not capable of forming estrogen, yet it nonetheless has a much higher affinity for the aromatase enzyme (which converts testosterone to estrogen) than testosterone does. That means in administering it with testosterone or another aromatizable compound, it prevents estrogen build-up because it binds to the aromatase enzyme very strongly, thereby preventing these steroids from interacting with it and forming estrogen. So Mesterolone use has the extreme benefit of reducing estrogenic side-effects and water retention noted with other steroids, and as such still help to provide mostly lean gains. Its also been suggested that it may actually downgrade the actual estrogen receptor making it doubly effective at reducing circulating estrogen levels.
When used as an ancillary, it can be taken by male athletes and bodybuilders all throughout their cycle length at 50 – 100mg per day, as there is no limit to how long it can be utilized for. Some individuals prefer to also run Proviron as a PCT (Post Cycle Therapy) drug in order to reduce Estrogen levels and boost fertility. Although this can be done, there are much better compounds with similar (and stronger) effects for PCT. When the risk of even weak endogenous Testosterone suppression is thrown into the mix with Proviron, it is advised to avoid the use of Proviron for PCT purposes unless there are no other options available. During a period in which individuals are attempting to recover their natural endogenous Testosterone levels, any threat no matter how minimal to endogenous Testosterone production should be unwelcome and avoided at all costs.