Does Winstrol aromatize into estrogen?
There has been substantial debate over whether or not Winstrol aromatizes or not. In the absence of a 3-keto group (needed for androgen binding) it is a rather weak androgen. It is also a 5-alpha reduced compound (5-alpha reduction essentially disrupts the bond at the 4th and 5th positions, which is required for estrogen conversion via aromatase), and this has lead to the belief that Winstrol may have some use in blocking estrogen from other steroids it is stacked with. This concept appears to be unsubstantiated, however.
Winstrol has also been touted to have significant antiprogestagenic effects due to binding at the progesterone receptor, without progesterone stimulation. Nonetheless, for these reasons Winny has been felt to be a good "cutting" drug. The current feeling is that it does not aromatize, or if it does, it does so only weakly.
I have no experience with a Winstrol-only cycle. If you are thinking of doing this without any concomitant anti-estrogen therapy, it might be adviseable to have these ancillaries on hand in case symptoms of estrogen conversion occur. This would be true after the cycle as well.
Certainly, if anyone has any first-hand experience with this, please share the experience with us...