Diuretics, which increase the production of urine, and masking agents, chemical compounds which interfere with drug tests, are banned for two reasons. ... Secondly, increased urine production depletes the concentration of both the banned drugs and their metabolites, making their detection more difficult.
Diuretics are banned in all sports because they can cause rapid weight loss and can act as masking agents (to hide the effects of other prohibited substances) both in and out of competition.
