The relation between body mass index and body fat percentage in Brazilian adolescents: assessment of variability, linearity, and categorisation

• Published in: Annals of human biology Vol. 48; no. 5; pp. 437 - 442
• Main Authors: Pacheco, Matheus, de Maio Godoi Filho, José Roberto, Nunes da Silva Filho, José, Pontes Dos Santos, Josivana, Dos Santos Farias, Edson
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 01-08-2021
• Subjects: Adipose Tissue - metabolism; Adolescent; Anthropometry; Body Composition; body composition population characteristics anthropometry; Body Mass Index; Brazil; Child; Humans; Brazil; Body composition population characteristics anthropometry
• ISSN: 0301-4460; 1464-5033
• DOI: 10.1080/03014460.2021.1982002

Reliable but accessible measures to capture body composition are highly important as the world is in an era of obesity-increase. The most used measure, the body mass index (BMI), nevertheless, has been judged as non-reliable to estimate body fat percentage (BF%). The present manuscript assessed the criticisms of BMI as a predictor of BF% and the BMI-based categories of nutritional status. 4164 children/adolescents from 9 to 18 years of age from Porto Velho, Brazil, had their anthropometric and skinfold measures taken. Controlling for socioeconomic status, school (private, public), sex and age, we compared proposed models/variables in the literature relating BMI and BF%. We evaluated the functions and the residual data to understand the variability of BF% estimate per BMI and evaluated three possible categorisations from BMI to predict BF% nutritional status. The function utilising (linear) BMI was the best to predict BF% (
= 0.70) with a variability of only 6.49% around the function. Nevertheless, no categorisation of nutritional status was reliable to predict the nutritional status of individuals. BMI is reliable to estimate BF%. Nevertheless, new normative values must be proposed; the original categorisation fails to capture the nutritional status of children/adolescents from this region.