Femara is an aramotase inhibitor. It blocks aramotizing steriods from converting to estrogen. Nolva and Clomid are estrogen antagonists. Unlike aramotase inhibitors, estrogen anagonists do not prevent aramotizing steroids from converting, they just compete with the receptors. They can both stimulate testosterone production post cycle, but via different mechanisms of action. An aramotase inhibitor reduces total estrogen. Estrogen is a strong variable in the HTPA loop which signals the testies to produce testosterone. Estrogen antagonists do not reduce total estrogen, but because they have a higher affinity than estrogen for the targeted tissues, it fools the body into believing there is an estrogen deficit and again, testosterone is produced. However, estrogen is beneficial to maintaining gains, so estrogen antagonists are generally preferred post cycle.
