Hide/Show Apps

Evaluation of body composition using three different methods compared to dual-energy X-ray absorptiometry

Duz, Serkan
Koçak, Mehmet Settar
Korkusuz, Feza
In this study, we compared the simple methods of skinfolds, ultrasound, and bioelectrical impedance analysis (BIA) against the standard of dual-energy X-ray absorptiometry (DEXA) in the assessment of body fat in normoactive Turkish male and female university students. We wished to develop new regression equations to more accurately predict percent body fat from skinfolds and ultrasound for this group of individuals. One hundred and four male (age 22.22.5 years; height 1.770.06 m; mass 74.910.4 kg) and one hundred and four female (age 21.91.9 years; height 1.650.06 m; mass 55.67.9 kg) students aged 18-26 years participated in the study. Analysis of variance and confidence intervals were used to compare mean percent body fat derived from skinfolds, ultrasound, BIA, and DEXA measurements, while intra-class correlation coefficients and Pearson correlation coefficients were used to evaluate the strength of the relationship between the methods. Bland and Altman plot analysis was used to evaluate the strength of agreement of the three methods with DEXA. Moreover, multiple regression analyses were conducted to develop new regression equations to predict percent body fat from subcutaneous fat thickness measured at three sites. The accuracy of the predictive equations was assessed by a cross-validation test. Mean percent body fat derived from DEXA (18.56.2% for males, 28.41.3% for females) was found to be significantly (p0.01) greater than that derived from skinfolds (12.45.5% for males, 20.81.0% for females), ultrasound (12.07.8% for males, 25.01.4% for females), and BIA (13.74.9% for males, 19.21.0% for females) in both males and females. According to the Bland and Altman plot analysis, ultrasound gave the closest results to DEXA for females and males and females combined, whereas BIA gave the closest results to DEXA for males. Skinfolds were the second closest measure to DEXA for all groups. Results of the regression analysis showed that measurement of subcutaneous fat thickness at three sites by skinfolds and ultrasound best predicted percent body fat for males and females respectively. Multiple correlations using three sites simultaneously in the skinfold measurements were r=0.92 ([image omitted] =2.4) and r=0.91 ([image omitted] =2.8), and in the ultrasound measurements were r=0.93 ([image omitted] =2.3) and r=0.90 ([image omitted] =3.0), for males and females respectively. In conclusion, comparison of the methods revealed that the three techniques could not be used interchangeably in this population. However, with these new regression equations, ultrasound and skinfolds are confirmed to be accurate, portable, and non-invasive tools for use in field studies. As a result, ultrasound can be used accurately on all individuals, regardless of whether they are obese or thin.