In the aromatization process, the aromatase enzyme converts these androgens to estrogen. If this conversion is excessive, bloat, depression, loss of libido, impaired fat loss, or even gynecomastia can occur. An aromatase inhibitor (AI) is an effective way to solve this problem. In contrast to Arimidex and letrozole which work by reversibly blocking access to the aromatase enzyme, Aromasin actually inactives individual enzyme molecules when it binds to them.