So we really need to devise molecules that either possess only anabolic activity or have androgenic activity. Nature has however devised our body in a fashion that it has become difficult to completely separate these two activities. We need a steroid skeleton for both activities. An electronegative atom is necessary for both activities. Cis ring fusion is not active.
Some natural androgens have greater androgenic activity than anabolic activity.
Bicalutamide and Flutamide. It is interesting to see that none of these have structures closely resembling the testosterone. Another anti-androgen is Danazol. This drug is used in the treatment of endometriosis which is the growth of endometrial tissue growing outside the uterus, especially in the pelvis. Danazol is a weak androgen and it binds to numerous steroid hormone receptors and blocks the synthesis of estradiol, progesterone, testosterone, and glucocorticoids.