If you click on one of the reviews in the list, a pop up will show you the 'whole' review, which contains the Bitterness Rating. Heavy loosely means if it's a good muscle relaxant. People refer to a good Heavy kava as being glued to the couch unable/unwanting to move much or not generally able to answer an important phone call (i.e. you just missed winning a 3 Million dollar sweep-stake)