For some sports there are weight classes. A person may attempt to lose weight to meet a cutoff by intentional loss of water.
People who may attempt to lose weight by intentional water loss:
(1) wrestlers, boxers, martial artists, etc
(2) jockeys
(3) people obsessed about weight
Methods may include:
(1) wrapping the body in plastic or saran wrap before exercising
(2) use of a sauna or hot box
(3) diuretic use
(4) laxative use
Any weight loss is water and temporary.
Significant problems can occur with:
(1) Electrolyte imbalance.
(2) Heat stress, especially during the summer.
(3) Toxicity of medications or herbal products used.
(4) Comorbid conditions like renal dysfunction.