Impact of total body water fluctuations on estimation of body fat from body density

Abstract

Impact of total body water fluctuations on estimation of body fat from body density. Med. Sci. Sports Exerc, Vol. 21, No. 1, pp. 96-100, 1989. The purpose was to investigate the possibility that variability in body weight in females due to water retention causes differences in body density (Db) values determined by hydrostatic weighing (HW). Determination of total body water (TBW) and Db were concurrently measured in seven females who experienced considerable fluctuations in body weight (1.5-4.5 kg) and seven males, ages 19-24. Females were measured when they felt they were at their lowest (LO) and highest (HI) body weights (BW) during a menstrual cycle. Males were randomly tested approximately 3 wk apart. Mean values of selected variables were compared in the LO vs HI testing sessions by paired l-tests. Significant mean differences were found in the females (P-1) (LO=1.0430, HI=1.037), and percent body fat (%BF) as determined by HW alone (LO=24.8%, HI=27.6%). Variables significant at the PP<0.01) in the males (LO=74.3, HI=74.6). It is concluded that changes in TBW can in part result in significantly different Db values obtained from HW in females who did experience perceptible changes in BW during a menstrual cycle. The remaining differences may be due to changes in fat and protein content or methodological errors.