THE PERFORMANCE OF AN INFRARED INTERACTANCE INSTRUMENT FOR ASSESSING TOTAL-BODY FAT

Infra-red interactance has been evaluated as a technique for measuring total body fat in comparison with a range of alternative methods. The alternative techniques employed were neutron activation analysis, tri tiated water dilution, whole-body potassium-40 counting, skinfold anth ropometry, bioelectrical impedance analysis and the body mass index. T he study group consisted of 43 healthy adults (16 males and 27 females ). For 11 women, measurements were obtained before and after 11 weeks on a very low-calorie diet, giving a total of 54 sets of data. Correla tion coefficients between infra-red interactance and the other techniq ues varied between 0.58 (p < 0.0002) and 0.80 (p < 0.0001) for females , and between 0.64 (p < 0.009) and 0.94 (p < 0.0001) for males. The av erage fat for the study group was underestimated by 15% using infra-re d interactance in comparison with the average fat obtained from the ot her techniques. It was also noted that the infra-red interactance inst rument yielded a very narrow range of body fats in females in comparis on with the other techniques. It is essential that these differences a re reconciled before infra-red interactance takes a significant role i n body composition analysis.