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The Body Mass Index (BMI) is one of the most widely used health metrics today, but its origins and limitations tell a much more complex story. Developed in the 19th century, BMI was never intended to be a universal measure of individual health, but for averages of a population.
The Origins of BMI
BMI was devised by a Belgian Mathematician, Astronomer and Statistician, in 1835. Adolphe Quetelet was a brilliant polymath, but not a physician. His goal was to understand population trends and averages; not individual health. The BMI formula (weight in kilograms divided by height in meters squared) emerged as part of his work on the "average man" to identify statistical norms in human populations (Eknoyan, 2007).
Quetelet invented BMI, he acknowledged that human diversity makes it impossible for a single mathematical formula to fully encapsulate health. He observed that "Nothing could be more interesting, above all in studying the moral development of man, than to follow simultaneously the development of the organs most directly connected with our actions, and to estimate to what extent the instrument is in concord with the effects produced by it" (Quetelet, 1842). He knew the that measuring body composition was the way forward.
Why BMI Took Off
BMI became widely adopted in the late 20th century for its simplicity. This led to public health officials using it as a quick and cost-effective way to access obesity levels across large populations. However, BMI was never validated on diverse ethnic groups; and was derived primarily from European men (Tillin et al., 2015).
The Limitations of BMI
A One-Size-Fits-All Approach: BMI assumes all body shapes are the same. For example, a highly muscular athlete may have a "high BMI" despite being healthy, while someone with a normal BMI could have dangerous levels of visceral fat around the middle (Golubnitschaja, 2021).
Gender and Ethnic Biases: BMI was initially validated on men, particularly white European men. It doesn’t account for differences in fat distribution or muscle mass as seen in women or individuals of different ethnic backgrounds (Jackson et al., 2010).
No Insight Into Health: BMI doesn’t measure critical factors like blood pressure, cholesterol, or metabolic health, making it an incomplete picture of well-being (Mesa, 2024).
Why We Need Alternatives
Now new metrics like the Body Volume Index (BVI) are gaining traction because they offer a better view of health. BVI uses 3D imaging to assess body composition, including fat distribution and visceral fat levels, which are better predictors of health risks.
Why is BMI Useful? Let's Move Beyond BMI.
In truth, BMI has now served its purpose as a population-level tool, but its use for individual health assessments has done more harm than good. Quetelet himself likely wouldn’t have endorsed its current use for measuring individuals as he never meant it to be used like that. As we advance in understanding health, embracing more inclusive, and more accurate measures like BVI are not just necessary, but long overdue.
Let’s honour Quetelet’s legacy by recognising BMI for what it is: a mathematical model, not the definitive measure of health. But also, let's move on and embrace BVI as a new measure for the 21st Century.
Reference List
Eknoyan, G., Quetelet., A (1796–1874)—the average man and indices of obesity, Nephrology Dialysis Transplantation, Volume 23, Issue 1, January 2008, Pages 47–51, https://doi.org/10.1093/ndt/gfm517
Golubnitschaja, O., Liskova, A., Koklesova, L., Samec, M., Biringer, K., Büsselberg, D., Podbielska, H., Kunin, A. A., Evsevyeva, M. E., Shapira, N., Paul, F., Erb, C., Dietrich, D. E., Felbel, D., Karabatsiakis, A., Bubnov, R., Polivka, J., Polivka, J., Jr, Birkenbihl, C., Fröhlich, H., … Kubatka, P. (2021). Caution, "normal" BMI: health risks associated with potentially masked individual underweight-EPMA Position Paper 2021. The EPMA journal, 12(3), 243–264. https://doi.org/10.1007/s13167-021-00251-4
Jackson, A. S., Ellis, K. J., McFarlin, B. K., Sailors, M. H., & Bray, M. S. (2009). Body mass index bias in defining obesity of diverse young adults: the Training Intervention and Genetics of Exercise Response (TIGER) study. The British journal of nutrition, 102(7), 1084–1090. https://doi.org/10.1017/S0007114509325738
Mesa, N. (2024). We’ve been measuring BMI since the 70s - but is the flawed metric still helpful? National Geographic. https://www.nationalgeographic.com/science/article/why-is-bmi-inaccurate#:~:text=BMI%20can't%20tell%20what,normal%E2%80%9D%20BMI%2C%20Stanford%20says.
Quetelet LA. A treatise on man and the development of his faculties. 1842. Obes Res. 1994 Jan;2(1):72-85. doi: 10.1002/j.1550-8528.1994.tb00047.x. PMID: 16353611.
Tillin, T., Sattar, N., Godsland, I. F., Hughes, A. D., Chaturvedi, N., & Forouhi, N. G. (2015). Ethnicity-specific obesity cut-points in the development of Type 2 diabetes - a prospective study including three ethnic groups in the United Kingdom. Diabetic medicine : a journal of the British Diabetic Association, 32(2), 226–234. https://doi.org/10.1111/dme.12576
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