Masteron is a derivative of DHT (as you can tell from its chemical name: 2a-methyl-dihydro-testosterone propionate), but what they fail to tell you is that DHT and its derivatives are commonly used in treatment of certain forms of breast cancer (see the etymology here: MASTectomy, gynocoMASTia, MASTeron, get it?). Masteron is not clinically used for weight gain, so this makes it a very unique steroid from that perspective. Unfortunately, much of the information on Masteron available in medical journals doesnt focus on weight or strength gain or even fat loss, for those reasons.
Most information on Masteron focuses on its use in treating certain forms of breast cancer, and it does this reasonably well. To give you an idea, Masteron + Tamoxifen actually fared better than Chemotherapy for immediate objective responses from patients .So? What does this tell us? Well, this makes it a very exciting drug for a lot of reasons. Clearly it wont aromatize at all nor will it have progesteronic sides, remember, Nolvadex are used to reduce estrogen for breast cancer patients, so a drug used to treat breast cancer obviously wouldnt convert to estrogen…and in fact Masteron may interact with the aromatase enzymes to inhibit aromatization of other steroids into estrogen, and may additionally interact with estrogen at the receptor site.
This is how it helps to combat breast cancer, obviously, but this could also be part of the reason that Masteron is considered a “cutting” or “Pre-contest” drug. Masteron may actually be very useful for combating estrogenic/progesteronic side effects yes, you read that right, if you include Masteron in your cycle, you may not need other “ancillary” drugs like Arimidex or Letrozole). Hence, much like Proviron, Masteron could be used as an anti-side-effect-drug (remember, most ancillary drugs we use to combat estrogenic sides, like nolvadex, letrozole, and arimidex were originally developed to combat breast cancer…and thats exactly what Masteron was developed and used for).
Along a similar line, being a DHT (DiHydroTestosterone) derivative, its got a very nice ability to add muscle hardness to an already lean physique, remember, Masteron has a deceivingly low anabolic/androgenic ratio, but since DHT is 5x as androgenic as testosterone and has a 3-4x higher affinity to receptor sites, Masteron provides a lot of “bang for the Buck” when examined on a Mg for Mg basis.