The effects of acute water ingestion on body composition analyses via Dual-Energy X-Ray Absorptiometry

To assess the influence of acute water ingestion on body composition analyses via Dual-Energy X-Ray Absorptiometry (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.

Paired sample t-test analyses revealed significant a increase in body mass of 0.46 ± 0.1 kg [t(99) = 42.6, p < .0001]. There were no significant changes in fat mass (-10.6 ± 493.4g). In contrast, 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].

Results indicate that acute water ingestion before a DXA analysis will significantly influence body composition. More precisely, acute ingestion of 500 ml of water will significantly inflate fat free mass as well as lower percent body fat. While the values were of small magnitude, these results highlight the importance of the control of liquid ingestion prior to DXA scans for body composition measurement.