20 Apr Acute Response to Water Ingestion on Body Composition
INTRODUCTION & PURPOSE
Hydration status affects the body composition estimates from bioelectrical impedance (BIA). This lack of concern with hydration status and liquid/food ingestion in the accuracy of Dual-Energy X-Ray Absorptiometry (DXA) measurement is also present in the National Health and Nutrition Examination Survey documentation of DXA assessment procedures. In fact, technicians are not instructed to ask participants about their current hydration status or liquid/ food ingestion.
There are many studies that have investigated this topic, but the variability of the results is high, and the samples are small in some works. In this sense, the purpose of this study was to determine the influence of acute water ingestion on body composition analysis via DXA.
One hundred (44 females; 56 males; Age = 24.2 ± 6.7 yrs; Height = 175.8 ± 12.1 cm; Body Mass = 76.1 ± 16.5 kg) volunteers took part in this study. Participants underwent an initial DXA scan. Immediately following the DXA scan, each participant consumed 500 ml of water. Participants body mass was assessed again and immediately completed a second DXA scan. Total body fat mass, fat free mass, and percent body fat were quantified. Paired sample t-test and Pearson correlations were utilized to determine mean differences and the relationship between initial and secondary measures.
All results are in Table 1.
- Paired sample t-test analyses revealed significant an increase in body mass of 0.46 ± 0.1 kg [t(99) = 42.6, p < .0001], which was consistent with the quantity of water ingested (500 ml).
- A meaningful mean increase in fat free mass of 525 ± 615 g (t(99) 1⁄4 8.5, p < .001) was also observed.
- There were no significant changes in fat mass (−10.6 ± 493.4g).
- There was a significant increase in lean mass (524.9 ± 615.1g) [t(99) = 8.5, p < .001].
- Overall, there was a significant decrease in percent body fat of −0.16% [t(99) = 2.4, p = .02].
Table 1. Pre- and post-water ingestion of all study participants (N = 100).
NOTE: Results presented as mean ± SD; *p .05.
- From a practical perspective, and considering the large sample size that included both males and females in this study, these findings highlight the importance of standardizing protocols (times and measuring conditions) when DXA is used for body composition analysis.
- Soccer players should be instructed to maintain specific hydration conditions (neither under nor over-hydrated) to avoid errors in variables frequently used (eg, interlimb comparison) in soccer such as Fat Free Mass or Body Fat percent.