Medical experts are calling for a BMI review due to its racist past

It could misrepresent millions of people's health

BMI is being reviewed again after experts look into its questionable origins. Image: Getty

Having long been used as a key indicator of a person’s health, the effectiveness of the BMI scoring system is coming under fire again. 

Medical experts are once again calling the accuracy and validity of the Body Mass Index (BMI) into question after the American Medical Association noted the tool’s racist history and exclusion of non-white populations. 

Having been popularly used by medical professionals as a measure of a person’s health and weight for decades in Australia and around the world, its effectiveness has come into question more and more in recent years as researchers look to more advanced ways of assessing a person’s wellbeing. 

Now, experts are once again encouraging the medical industry to use BMI in conjunction with other health considerations rather than seeing it as the primary test and leading determinant.  

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In Australia, a BMI within the range of 18.5 to 24.9 is considered healthy. Anything below 18.5 is considered underweight, while anything between 25 and 29.9 is considered overweight, and anything over 30 is considered obese. 

Following its annual meeting in June 2023, the American Medical Association noted the “significant limitations associated with widespread use of BMI in clinical settings,” noting its “historical harm” and “use for racist exclusion.” 

The use of BMI calculations began gaining widespread popularity in a modern context the 1970s after a physiologist Dr Ansel Keys termed the count body mass index and promoted the tool’s use as a beneficial way to make fast health assessments. But the roots of the BMI actually date back almost 200 years. 

Originally known as the Quetelet Index, the study was named after astronomer, mathematician and statistician Adolphe Quetelet, who was interested in finding what he dubbed the “normal man”. By taking the measurements of a large group of people, he reasoned, a median could be identified and then used as a guide for what could be considered ‘normal’. 

A set of numbers on the scale, like BMI, is only one aspect of health. Image: Getty

While the basic principle sounds okay in theory, there were two big problems with Quetelet’s plan from the very outset. Firstly, he was not trained in medicine or the study of human biology. Secondly, and most relevantly to today, all of the participants in his study were Western European men, namely Scottish and French men. In ignoring the body types of non-white populations and women entirely, Quetelet’s Index not only went on to support the eugenics movement but also acted as a scientifically justified basis for extremely racist and brutal policies in the decades that followed. 

When Keys revisited the Index in the 1970s and suggested the median be used as a way to measure body fat, he did his own measurements and studies, but again, only men were measured. While Keys did at least include participants from Japan, Italy, Finland and the Bantu people of Africa, the study measured just 7,426 people, and even he noted at the time of his findings being published that the work  “could not be suggested to be a representative sample of Bantu men in general.” 

So how did an average measurement that can’t be considered representative of racial groups in general and that excluded women from it become a popularised method of weight measurement? 

As Dr Jamy Ard, a professor of epidemiology and prevention a the Wake Forest University School of Medicine in the US, recently pointed out, “It is easy to calculate and essentially costs nothing, so this makes it very hard to replace.”  

According to census data from 2021, 39.9 per cent of America’s population identifies as non-white. Of this, 18.5 per cent were Hispanic and 12.2 per cent were Black.

Measurements can form part of a person's health understanding. Image: Getty

In Australia, 27.6 per cent of our population was born overseas, with India, China and the Philippines being among the top five most common countries of birth. This population, combined with our Indigenous and Torres Strait Islander population, makes for millions of Australians still receiving health guidance from a metric that was created using data primarily from populations that do not represent their own. 

As the AMA notes, “BMI is based primarily on data collected from previous generations of non-Hispanic and white populations.” And while the tool “significantly correlated with the amount of fat mass in the general population,” it “loses predictability when applied on the individual level.” 

The AMA also pointed out that “relative body shape and composition differences across race/ethnic groups, sexes, genders and age-span is essential to consider when applying BMI.” 

Instead of doing away with BMI entirely, it’s now being recommended that it be used in conjunction with other measures like assessing where people carry fat, measuring cholesterol levels and monitoring blood pressure levels.

Originally published as Medical experts are calling for a BMI review due to its racist past