TABLE 3.

Multiple linear and log-binomial regression models relating the association of adequate intake of water stratified by weight status to urine osmolality and the PR of hypohydration in adults aged ≥20 y in the United States, 2009–2012¹

	Urine osmolality, mOsm/kg			Hypohydration2
	Underweight or normal weight	Overweight	Obese	Underweight or normal weight	Overweight	Obese
	Model 1	Model 2	Model 3	Model 4	Model 5	Model 6
Low water intake	Reference	Reference	Reference	Reference	Reference	Reference
Adequate water intake	−122.4 ± 19.73	−99.5 ± 16.4	−65.2 ± 9.1	0.56 (0.43, 0.73)4	0.67 (0.57, 0.79)	0.78 (0.70, 0.88)
P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
n	2824	3190	3587	2824	3190	3587

¹Models were stratified by weight status because the interaction between weight status and water intake status was jointly significant in both linear (F = 6.27, P = 0.005) and log-binomial (F = 4.78, P = 0.015) regressions. All models were adjusted for the following variables: age category (20–39, 40–59, and ≥60 y); sex; race and Hispanic origin; time of examination; meeting physical activity guidelines; high caffeine intake, alcohol intake, and caloric intake; and diabetes. BMI (in kg/m²) categories were as follows: underweight or normal weight, <25; overweight, 25 to <30; and obese, ≥30. Low water intake was defined as follows: men, <3.7 L; nonlactating women, <2.7 L, and lactating women, <3.8 L; and adequate water intake was defined as follows: men, ≥3.7 L; nonlactating women, ≥2.7 L; and lactating women, ≥3.8 L. Data source: NHANES (26). PR, prevalence ratio.

²mOsm/kg ≥831 − [3.4 × (age − 20 y)].

³Beta ± SE (all such values).

⁴PR; 95% CI in parentheses (all such values).