The need to redefine age- and gender-specific overweight and obese body mass index cutoff points

A M Nevill,G S Metsios

doi:10.1038/nutd.2015.36

Abstract

For convenience, health practitioners and clinicians are inclined to classify people/patients as overweight or obese based on body mass index (BMI) cutoff points of 25 and 30 kg m−2 respectively, irrespective of age and gender. The purpose of the current study was to identity whether, for the same levels of adiposity, BMI is the same across different age groups and gender. A two-way ANCOVA revealed significant differences in BMI between different age groups and gender (plus an interaction), using body fat (%) as the covariate, data taken from a random sample of the English population (n=2993). Younger people had greater BMI than older people for the same levels of adiposity (differences ranged by 4 BMI units for males, and 3 BMI units for females). In conclusion, if BMI thresholds for overweight (BMI=25 kg m−2) and obese (BMI=30 kg m−2) are to reflect the same levels of adiposity across all gender and age groups within a population, then age- and gender-specific BMI adjustments outlined here are necessary to more accurately/fairly reflect the same critical levels of adiposity.

Highlights

Body mass index (BMI) is undoubtedly the most frequently used proxy of adiposity/obesity in large epidemiological studies in both healthy and diseased populations
Despite its wide use, which pertains to convenience since it only requires the measurement of height and mass, BMI has been frequently criticised as having various deficiencies as a measure of obesity[1] both for healthy and diseased populations.[2,3]
One of the major issues with BMI is that it does not reflect the changes in body composition that occur with age, in particular the presence of sarcopaenia, which is characterised by reduced muscle mass and increased adiposity

Summary

Introduction

Body mass index (BMI) is undoubtedly the most frequently used proxy of adiposity/obesity in large epidemiological studies in both healthy and diseased populations. One of the major issues with BMI is that it does not reflect the changes in body composition that occur with age, in particular the presence of sarcopaenia, which is characterised by reduced muscle mass and increased adiposity. As such the utilisation of BMI in evidence-based approaches relevant to dietary interventions and/or clinical decision making needs to be reconsidered and where appropriate, readjusted. The aim of the present study was to investigate the cutoff points of BMI in relation to adiposity in a large cohort of participants in order to validate if the established cutoff points accurately reflect adiposity.

Objectives

Methods

Results

Conclusion