Structurally Trenbolone is a 19-nor steroid, being derived from the anabolic nandrolone. Its additional two alterations however (c9 and c11 double bonds) make Trenbolone very different in appearance than its parent nandrolone. First, as mentioned estrogenic activity has been eliminated. This is a result of the c 9-10 double bond which occupies a bond that would be necessary for aromatization of the A ring to be possible. This bond does not appear to be removed metabolically, which is the only way estrogen conversion would be possible with this compound. Although nandrolone is rarely thought of an estrogenic steroid, conversion to estradiol is still possible to a low extent. The fact that trenbolone does not convert to estradiol therefore remains to be a significant difference between the two steroids.
Its lack of estrogenic activity has made trenbolone very appealing for competitive athletes looking to shed fat, while at the same time trying to avoid water retention. Likewise “tren” can give us the high androgen content needed in order to elicit a very hard, defined physique. While it is a noteworthy hardening agent, this is certainly not the only benefit to this steroid however, it also a noteworthy anabolic.