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.