Assessment of body fat in physically active young people: anthropometry vs bioimpedance

To assess the level of agreement between the anthropometrical method and several bioimpedance (BIA) devices to estimate the fat mass in a group of physically active young people. 55 students of Physical Activity Sciences and Sports of the INEFC of Barcelona; 29 men (age: 24.7 +/- 4.7 years; BMI: 23.4 +/- 1.8) and 26 women (age: 22.9 +/- 3.5; BMI: 21.5 +/- 1.9). All of them voluntarily gave their informed consent. Anthropometrical assessment was done according to the International Society for the Advancement Kinanthropometry (ISAK) protocol, the fat % was calculated by the Siri's equation and was compared with that obtained by 4 different BIA devices: Biospace Inbody 720, Tanita BC400, Tanita TBF-521, and Omron BF-300. To assess the level of agreement of the results, the interclass correlation coefficient and the Bland Aldman method were used. The estimated fat mass, in men, by the anthropometrical method was 7 +/- 2.2 kg. The results by the BIA systems were: 7.4 +/- 3 kg; 5.6 +/- 2.2 kg; 5.7 +/- 2.5 kg, and 7.4 +/- 3 kg for Biospace Inbody 720, Tanita BC400, Tanita TBF521, and Omron BF300, respectively. In women, the results were 10.4 +/- 2.7 kg of fat mass by means of the anthropometrical method and 10.3 +/- 2.9 kg, 11 +/- 3.3 kg, 11.5 +/- 3.0 kg, and 10 +/- 2.9 kg for Biospace Inbody 720, Tanita BC400, Tanita TBF521, and Omron BF300, respectively. In the male group, the level of agreement between anthropometrics and BIA devices was moderate-poor, whereas in women there was a good correlation between both techniques for estimating the body fat when the Biospace Inbody 720 and Tanita BC400 devices were used.