By doing so, they prevent almost all conversion of androgens to estrogens, thus increasing
the total amount of testosterone
in your body. As a result, even more testosterone convert to dihydrotestosterone (DHT) via the 5-alpha reductase enzyme. AIs, like the three listed, cut your hair off from estrogen AND increase your DHT.
However, finasteride or dutasteride may be helpful options (avodart, propecia, etc). These are 5-alpha reductase inhibitors.