Winstrol is a popular brand name for the anabolic steroid stanozolol. This compound is a derivative of dihydrotestosterone, although its activity is much milder than this androgen in nature. It is technically classified as an anabolic steroid, shown to exhibit a slightly greater tendency for muscle growth than androgenic activity in early studies. While dihydrotestosterone really only provides androgenic side effects when administered, stanozolol instead provides quality muscle growth and is still a reliable builder. Its efficacy as an anabolic could even be comparable to Dianabol, however Winstrol does not carry with it the same tendency for water retention. Stanozolol also contains the same c17 methylation we see with Dianabol, an alteration used so that oral administration is possible. To spite this design however, there are many injectable versions of this steroid produced.
Structurally stanozolol is not capable of converting into estrogen. Likewise an antiestrogen is not necessary when using this steroid, gynecomastia not being a concern even among sensitive individuals. Since estrogen is also the culprit with water retention, instead of bulk Winstrol® produces a lean, quality look to the physique with no fear of excess subcutaneous fluid retention. This makes it a favorable steroid to use during cutting cycles, when water and fat retention are a major concern. It is also very popular among athletes in combination strength/speed sports such as Track and Field. In such disciplines one usually does not want to carry around excess water weight, and may therefore find the raw muscle-growth brought about by Winstrol® quite favorable over the lower quality mass gains of more estrogenic agents.