Defining body fatness in adolescents: a proposal of the AFAD-A classification

PLoS One. 2013;8(2):e55849. doi: 10.1371/journal.pone.0055849. Epub 2013 Feb 6.

Abstract

Aims: Body mass index (BMI) shows several limitations as indicator of fatness. Using the International Obesity Task Force (IOTF) reference and the World Health Organization (WHO) standard 2007 on the same dataset yielded widely different rates. At higher levels, BMI and the BMI cut-offs may be help in informing a clinical judgement, but at levels near the norm additional criteria may be needed. This study compares the prevalence of overweight and obesity using IOTF and WHO-2007 references and interprets body composition by comparing measures of BMI and body fatness (fat mass index, FMI; and waist-to-height ratio, WHtR) among an adolescent population.

Methods and results: A random sample (n = 1231) of adolescent population (12-17 years old) was interviewed. Weight, height, waist circumference, triceps and subscapular skinfolds were used to calculate BMI, FMI, and WHtR. The prevalence of overweight and obesity were 12.3% and 15.4% (WHO standards) and 18.6% and 6.1% (IOTF definition). Despite that IOTF cut-offs misclassified less often than WHO standards, BMI categories were combined with FMI and WHtR resulting in the Adiposity & Fat Distribution for adolescents (AFAD-A) classification, which identified the following groups normal-weight normal-fat (73.2%), normal-weight overfat (2.1%), overweight normal-fat (6.7%), overweight overfat (11.9%) and obesity (6.1%), and also classified overweight at risk and obese adolescents into type-I (9.5% and 1.3%, respectively) and type-II (2.3% and 4.9%, respectively) depending if they had or not abdominal fatness.

Conclusions: There are differences between IOTF and WHO-2007 international references and there is a misclassification when adiposity is considered. The BMI limitations, especially for overweight identification, could be reduced by adding an estimate of both adiposity (FMI) and fat distribution (WHtR). The AFAD-A classification could be useful in clinical and population health to identify overfat adolescent and those who have greater risk of developing weight-related cardiovascular diseases according to the BMI category.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / pathology*
  • Adiposity*
  • Adolescent
  • Body Composition
  • Body Mass Index
  • Child
  • Female
  • Humans
  • Male
  • Obesity / classification*
  • Obesity / epidemiology*
  • Overweight / classification
  • Overweight / epidemiology
  • Prevalence
  • Reference Values
  • Waist Circumference*
  • World Health Organization

Grants and funding

The study was supported by the Spanish Ministry of Health and Consumption Affairs (Programme of Promotion of Biomedical Research and Health Sciences, Projects 05/1276, 08/1259, and 11/01791, Red Predimed-RETIC RD06/0045/1004, and CIBERobn CB12/03/30038), Grant of support to research groups no. 35/2011 (Balearic Islands Gov. and EU FEDER funds), Spanish Ministry of Education and Science (FPU Programme, PhD fellowship to M.M.B.). The Research Group on Community Nutrition and Oxidative Stress, University of Balearic Islands belongs to the Centre Català de la Nutrició (IEC) and Exernet Network. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.