The composition of weight loss in dieting obese females by electrical methods

The fat and fat-free components of the weight loss of a group of obese females undergoing a clinically monitored dieting regime have been estimated by two noninvasive electrical techniques, bioelectrical impedance analysis (BIA) and tissue resonance impedance monitoring (TRIM). These two procedures are described and results presented for a group of volunteers representing a wide range of body mass index. During the 11 weeks of the study the members of the group were on a 405 kcal liquid ketogenic diet. Within experimental error, the estimates of changes in body composition by the two methods agree with each other and also with estimates determined by tritiated water dilution and neutron activation measurements on the same group of subjects. The average loss in body mass was 16.2 kg, representing approximately 18% of the average initial body mass. The loss comprised about 20% fat-free tissue and 80% fat tissue. The safety, convenience and non-invasive nature of the electrical techniques makes them useful additional procedures to be deployed in the routine monitoring of body composition.