Prediction of body fat in adolescents: validity of the methods relative fat mass, body adiposity index and body fat index.

Irismar G A Encarnação,Diego A S Silva,João C B Marins,Matheus S Cerqueira,Pedro M Magalhães

doi:10.1007/s40519-021-01301-6

Abstract

To verify the validity of anthropometric methods body adiposity index (BAI), relative fat mass (RFM) and body fat index (BFI) to estimate body fat percentage (%BF) in adolescents. A cross-sectional study was carried out with 420 Brazilian adolescents aged 15-19years, stratified by age (< 18years, n = 356; ≥ 18years, n = 64) and sex (boys, n = 216; girls, n = 204). The Anthropometric measurements height, body weight, hip circumference and waist circumference were collected to calculate the %BF by BAI, RFM, BFI methods. Subsequently, %BF was measured by dual emission X-ray absorptiometry (DXA), adopted as a reference method. In the statistical analysis of the data, the Pearson correlation test and the paired t test between %BF obtained by the equations and by the DXA were performed. The method validation criterion was that 68% of individuals should be within an acceptable error range of ± 3.5% of BF and Cohen's Kappa index ≥ 0.61. Additionally, the Bland-Altman graphical analysis was performed. All methods showed a high correlation with DXA. For the Kappa index, only the RFM reached the criterion in the total sample (0.67) and in the sample < 18years (0.68). None of the methods reached the criterion of 68% of the sample within the error range of ± 3.5% of BF. The BAI, RFM and BFI equations were not valid for predicting BF in the studied sample according to the criteria adopted regardless of sex or age. Level V, cross-sectional descriptive study.

Highlights

Since 1975 the number of people with obesity has tripled worldwide, with more than 340 million children and adolescents (5–19 years) in 2016 with overweight or obesity [1], which are risk factors for the development or maintenance of obesity in adulthood and the development of cardiovascular, musculoskeletal, metabolic diseases and some types of cancer [2,3,4,5].The body composition assessment in adolescence is important to identify the need to implement early lifestyle interventions to reduce morbidity and mortality in the short and long term [6], in addition to reducing spending in the public health sector [7]
The objective of the present study was to verify the validity of the Body Adiposity Index (BAI), Relative Fat Mass (RFM) and Body Fat Index (BFI) methods to %body fat (BF) prediction in Brazilian adolescents
The objective of the present study was to verify the validity of the BAI, RFM and BFI equations for predicting %BF with dual emission X-ray absorptiometry (DXA) as a reference method in Brazilian adolescents

Summary

Introduction

Since 1975 the number of people with obesity has tripled worldwide, with more than 340 million children and adolescents (5–19 years) in 2016 with overweight or obesity [1], which are risk factors for the development or maintenance of obesity in adulthood and the development of cardiovascular, musculoskeletal, metabolic diseases and some types of cancer [2,3,4,5].The body composition assessment in adolescence is important to identify the need to implement early lifestyle interventions to reduce morbidity and mortality in the short and long term [6], in addition to reducing spending in the public health sector [7]. All of these methods were simple and practical, presenting a better performance than the Body Mass Index (BMI) to estimate the body fat percentage (%BF) They showed other advantages, such as BAI and RFM does not require body weight measure to predict %BF, which can be a positive point in remote places. These methods were developed in adults of specific localities and ethnicities, the authors suggest the validation in other age groups and ethnicities [9,10,11] considering that the amount and distribution of BF may differ depending on these factors [12]

Methods

Results

Conclusion