Final answer:
A diuretic decreases body mass by increasing urine output through less water conservation and is used to treat various medical conditions while also affecting performance in some sports.
Step-by-step explanation:
A diuretic is a substance that decreases body mass to improve performance in some sports by increasing urine output and reducing water conservation by the body. Diuretics are commonly used to treat medical conditions such as hypertension, congestive heart failure, and fluid retention. Compounds like alcohol and caffeine act as diuretics; for example, alcohol does so by inhibiting the release of ADH (antidiuretic hormone), leading to decreased water reabsorption in the kidneys, and caffeine increases the glomerular filtration rate (GFR), which in turn increases urine volume.
Furthermore, diuretics in the form of prescribed medication can control electrolyte balance by affecting reabsorption of Na+ and Cl- ions in the nephron, notably in the ascending limb of the loop of Henle and the distal convoluted tubule (DCT), like loop diuretics or hydrochlorothiazide, respectively.