The effect of acute fluid consumption on measures of impedance and percent body fat estimated using segmental bioelectrical impedance analysis.
OBJECTIVE
To determine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) estimated using segmental bioelectrical impedance analysis (SBIA).


METHODS
Seventy-six healthy, recreationally active adults (41 women; 35 men) volunteered to participate in this study (mean+/-s.d.; age, 21.0+/-1.6 years; body mass index, 25.0+/-3.2 kg/m2). Subjects had their body composition assessed on three separate occasions. After a baseline measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE) or received nothing (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each fluid condition.


RESULTS
Twenty minutes after drinking a H2O or CHOE beverage, %BF (1.1 and 1.2%), impedance (12 and 14 Omega) and body mass increased significantly (P<0.001). During the CON trial, %BF (0.3 and 0.5%) and impedance (7 and 11 Omega) also increased significantly above baseline values at 40 and 60 min POST. However, the normal hourly variability was significantly (P<0.009) less than the observed fluid-induced %BF alterations. The greatest %BF increases were observed in the lightest subjects, who were women. Fluid type had no effect on the magnitude of change POST.


CONCLUSIONS
Twenty minutes after drinking, %BF estimates increased approximately 1.0% due to elevations in impedance and body mass. As such, we recommend adhering to the pretest fluid restriction guideline to avoid fluid-induced alterations in SBIA body composition measures. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.
Dixon
C B
CB
Department of Health Science, Lock Haven University, Lock Haven, PA, USA.
Ramos
L
L
Fitzgerald
E
E
Reppert
D
D
Andreacci
J L
JL
D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D001835:Body Weight / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004326:Drinking; D004573:Electrolytes / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D010992:Plethysmography, Impedance; D012737:Sex Factors; D013997:Time Factors; D014867:Water / Q000008:administration & dosage*; D055815:Young Adult
D004040:Dietary Carbohydrates; D004573:Electrolytes; D014867:Water