An analytic (noun) is very much like a diuretic. The purpose and results of the two are identical, what differs is the path, so to speak, used to achieve their goals. A diuretic causes excess water to be expelled from the body through the urinary tract. An analytic, on the other hand causes excess water to be expelled from the body through the digestive tract—i.e., the water comes out of your backside.
Doctors rarely prescribe analytics because most people are rather disgusted by the thought of water flooding out of their butts. Consequently, doctors almost always prescribe diuretics when a water pill is required. They typically reserve analytics only for people they really, really, really don’t like.