Abstract

This study analyzed the acute effect of water consumption on resting metabolic rate (RMR). It was hypothesized that water would have a small, nonclinically significant effect on RMR. Men and women ages 18–40 years participated in a crossover study in which each participant received a No Water and Water condition (order determined randomly) with a 7-day washout period between each condition. Both conditions began with visual analog scales to gauge hunger and thirst levels, urine spectrometry to quantify hydration status, and height and weight measurements. The No Water condition consisted of a 30-minute rest period followed by 45 minutes of RMR testing. The Water condition was identical except for the administration of 500 ml of purified water at 3 °C 10 minutes prior to the beginning of the RMR measurement. Resting metabolic rate testing was done via indirect calorimetry. There was not a condition-by-time difference in 24-hour resting energy expenditure, oxygen consumption, or metabolic equivalents when including all data points and controlling for nonlinearity (ps > 0.0682). There was a significant difference in respiratory quotient (RQ) (F = 13.73; p = 0.0006) with the No Water condition showing a slightly higher RQ than the Water condition. The nonlinear pattern was primarily driven by the first several minutes of testing. Accordingly, we completed analyses without the first 5 minutes of data. The results persisted; that is, there was no condition-by-time effect in 24-hour resting energy expenditure, oxygen consumption, or metabolic equivalents (ps > 0.2435). Further, the RQ remained significantly different (F = 10.57; ps > 0.0023); however, it was slightly higher in the Water condition. This study did not support our hypothesis that consumption of 500 ml of water would have a measurable effect on RMR and fuel utilization compared to not consuming water. Rather, this study replicates other studies that suggest there is not an acute measurable effect of water consumption on RMR. Nevertheless, one positive application of these findings is that water may be a suitable control in RMR studies. In addition, these results should not discourage overall water consumption for healthy functioning. Further, consumption of water-rich foods over time could be an effective strategy for weight management (as shown in other studies). Future studies could attempt to determine if larger volumes of water or different temperatures of water have an effect on RMR.

Degree

College and Department

Life Sciences; Exercise Sciences

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