Variability of water content of lean tissue of pregnant and nonpregnant rats and its effect on body fat estimation.
In humans, body fat is often estimated from body water. Measurements of the body water and estimates of the percent water in the lean tissue (WLT) are used to calculate the lean tissue which is then subtracted from body weight to estimate the quantity of body fat. The reliability of this method and the effect that pregnancy, obesity, fasting, and food restriction have on the body fat estimate derived from the mean WLT were assessed. Pregnant and nonpregnant rat carcasses were analyzed gravimetrically for water and for hexane extractable fat and the WLT was calculated. Mean WLT values differed significantly in pregnant and nonpregnant groups. In pregnant animals, prior food restriction or fasting significantly lowered the mean WLT. Estimates of individual fat content derived from the appropriate mean WLT varied from 63 to 332% of assay values. Thus body fat estimates derived from the mean WLT may be very inaccurate, particularly in fasted individuals.
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000818:Animals; D001823:Body Composition; D001834:Body Water / Q000032:analysis*; D005260:Female; D008433:Mathematics; D009765:Obesity / Q000473:pathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000473:pathology; D011270:Pregnancy, Animal; D051381:Rats; D011919:Rats, Inbred Strains