Body mass index (BMI) has long been used as a standard measure of health by medical professionals. However, recent policy changes by the American Medical Association (AMA) and England’s National Institute for Health and Care Excellence (Nice) have cautioned against relying solely on BMI for clinical assessments. This article explores the limitations of BMI and the importance of considering additional health indicators.

The Origins and Misuse of BMI: Originally developed in 1832 by Adolphe Quetelet, BMI was designed as a population-level tool to study health. However, in 1995, the World Health Organization established BMI criteria for weight classification, leading to its unintended use in individual health assessments. Even then, the World Health Organization emphasized that BMI should be interpreted alongside other determinants of health.

Limitations of BMI:

1. Body Composition: BMI fails to account for body composition, including fat, muscle, and bone proportions. Individuals with higher muscle mass, such as athletes, may have elevated BMI values despite having low body fat. Consequently, BMI alone may inaccurately label them as unhealthy.

2. Body Fat Distribution: BMI overlooks where a person stores their body fat, which is crucial as fat accumulation in certain areas poses greater health risks. Excess abdominal fat, in particular, is associated with conditions like type 2 diabetes and heart disease.

3. Ethnic Variations: The criteria for BMI classification were primarily developed using data from white populations, potentially limiting its accuracy and usefulness for individuals from diverse ethnic backgrounds. South Asians, for instance, may face obesity-related health risks at a lower BMI compared to white individuals.

4. Gender Differences: Men and women tend to store fat differently, and women generally have smaller body frames. Consequently, the relationship between BMI and health outcomes may vary between genders.

Considering Comprehensive Health Assessment: 

To obtain a more accurate picture of a patient’s health, practitioners are recommended to use BMI alongside other measurements, such as waist circumference and waist-to-hip ratio. These additional indicators provide insights into body fat distribution and overall health.

Implications and Conclusion: 

While BMI remains valuable for population-level studies on obesity, its limitations make it less useful for individual health assessments. The AMA’s decision to shift emphasis away from BMI and consider multiple health measures aligns with the need for better patient care and reduced weight-related stigma in healthcare settings.

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This article was originally published on The Conversation UK on June 26, 2023, at 3.03pm CEST. Authors: James King, David Stensel, and Dimitris Papamargaritis James King is an Associate Editor for the International Journal of Obesity. David Stensel is co-Editor-in-Chief for the International Journal of Obesity and receives research funding from the National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre. Dimitris Papamargaritis has received grant funding from Novo Nordisk A/S, Novo Nordisk UK Research Foundation, Academy of Medical Sciences/ Diabetes UK, and Health Education East Midlands. He has also been an National Institute of Health and Care Research Clinical Lecturer in Diabetes and Endocrinology and is associated with various academic committees and organizations focused on obesity and diabetes.