Diuretics
Sometimes called ""water pills,"" these are drugs and herbal preparations that remove excess water from a bodybuilder's system just prior to a show, thereby revealing greater muscular detail. Harsh chemical diuretics can be quite harmful to a weightlifter's health, particularly if they are used on a chronic basis. Two of the side effects of excessive chemical diuretic use are muscle cramps and heart arrhythmias (irregular heart beats).
a drug that increases the rate at which water is excreted through the kidneys
see the Misc.Fitness.Weights FAQ: Diuretics