Final answer:
Bathroom scales measure weight using springs that compress in proportion to a person's weight, but they cannot directly measure body water level.
Step-by-step explanation:
Bathroom scales measure weight by using springs that compress in proportion to a person's weight. These springs provide a measure of the force exerted by an object on the scale, which is then calibrated to display weight in units such as pounds or kilograms.
However, the claim of a bathroom scale to measure total body water level is not accurate. Bathroom scales cannot directly measure body water level. To accurately measure body water level, specialized equipment or body composition analyzers are used, which calculate it based on factors such as electrical impedance or density.