The effect on hydration of two diets, one with and one without plain water.

OBJECTIVE To measure the effect on hydration of two regimens, one that included drinking water as part of the dietary beverages and one that did not. METHODS In healthy, sedentary subjects, two different diets were evaluated for their effect on hydration. Trial A provided plain water to drink as part of the beverages served. Trial B omitted plain water from the beverages served. Twenty-seven males, during two three-day confinement periods, consumed one of two diets in a random, crossover and counterbalanced fashion, while diet, physical activity and environment were controlled and monitored. Body weight and 24-hour urine volumes were measured. Pre- and post-trial urine samples and 24-hour urines were assayed for osmolality, specific gravity, chloride, sodium and potassium, and sodium/potassium ratio was calculated. Twenty-four hour creatinine levels were determined. RESULTS No differences (p > 0.05) were found between trials for body weight or other indicators of hydration status measured. CONCLUSIONS Inclusion of plain drinking water compared to exclusion of plain drinking water in the diet did not affect the markers of hydration used in this study.