Aromasin or Exemestane is an unwanted by-product of Steroid use.   In some tissues of the male body, there is a nasty little Enzyme called  the “Aromatase” Enzyme.  This Enzyme is responsible for turning  Testosterone and other male hormones into female ones like Estrogen, and  Estradiol or other girly-like hormones. An abundance of Female hormones  in the male body can cause a whole list of bad side-effects, like male  breast tissue growth and water retention.  Bodybuilders  use a lot of different drugs and compounds to combat these bad side  effects.  The best way to keep Estrogen from causing problems is to make  sure it is never created in high amounts in the first place.  Using a  compound that inhibits the Aromatase Enzyme is a sure way to make sure Testosterone and other Steroids are never converted into side-effect causing Estrogen.  A compound that inhibit the Aromatase  Enzyme from creating Estrogen is called an Aromatase Inhibitor, or AI  for short. There are a lot of options out there when it comes to AI’s  (Aromatase Inhibitors), and Aromasin is certainly one of the most  popular options for bodybuilders that cycle steroids for a number of  reasons.Aromasin  is a suicidal Aromatase inhibitor, which makes it a better choice than  other AIs. Exemestane binds with aromatase enzymes and then subsequently  permanently disables the enzyme by destroying it.