Hydrostatic weighing without head submersion in morbidly obese females

This study tests the validity of hydrostatic weighing without head submersion (HWNS) for determining the body density (Db) of morbidly obese (MO) females. Eighty MO females who were able to perform traditional hydrostatic weighing at residual volume (HW) underwent four counterbalanced trials for each procedure (HW and HWNS) to determine Db. Residual volume was determined by oxygen dilution. Twenty subjects were randomly excluded from the experimental group (EG) and assigned to a cross-validation group (CV). Simple linear regression was performed on EG data (n = 60, means = 36.8 y, means % fat = 50.1) to predict Db from HWNS (Db = 0.569563 [Db HWNS] + 0.408621, SEE = 0.0066). Comparison of the predicted and actual Db for CV group yielded r = 0.69, SEE = 0.0066, E statistic = 0.0067, mean difference = 0.0013 kg/L. The SEE and E statistic for body fat were 3.31 and 3.39, respectively. Mean difference for percent fat was 0.66%. Results indicate that HWNS is a valid technique for assessing body composition in MO females.