Anastrozole has the ability to double a low testosterone male's bioavailable testosterone and increase his total testosterone by around two thirds. Anastrozole is used widely for just this purpose. One study looked at men over 60 years old and found an increase in testosterone of 62% and a decrease in estradiol, the "bad estrogen", of 24% for a net improvement in the testosterone-to-estradiol ratio of 115%. It took their total testosterone levels up from an average of 330 to 535 ng/dl.

Another study on infertile men with a T/E ratio less than 10 and total testosterone under 200 ng/dl found even more impressive results: total testosterone was increased by an average of 95%.

Anastazole actually works by binding to the aromatase enzyme that converts your testosterone into estrogen. Anastrozole effectively inhibits or blocks this conversion. One might expect estradiol to be affected more proportionately than testosterone, but in actuality it was testosterone that was affected more than estrogen in the above study.