Body composition in the elderly estimated with an electrical impedance method.

The purpose of the present study was to test the reliability and validity of a new electrical impedance method for estimating body composition in 35 healthy persons and patients in different sex and age groups, and to obtain basal data on the size of different body composition compartments in elderly individuals in health and disease. The reliability studies showed no significant differences with the new method in intraindividual comparisons before and after changing the positions of the electrodes, drinking of water, and overnight fasting, as well as at a double estimation on 2 consecutive days. The results with this method are compared to results from measurements of total body potassium and total body water, and from a four-compartment model technique using total body potassium and total body water. We conclude that the method has an acceptable reliability and validity and should be of great value not only in field studies but also in clinical practice. Data on body composition with the electrical impedance method are obtained from 147 individuals in different groups, namely healthy females, 80-81-year-old males, female patients from a nursing home, and patients of both sexes from a day care unit.