The One Anthropometric Measure We Need to Get Rid Of

The Body Mass Index, or BMI, was never designed to assess personal health. In 1832, Adolphe Quetelet, a Belgian statistician, developed the formula weight divided by height squared to create what he called the Quetelet Index, a measure of the average size of people within a population. More than a century later, in 1972, physiologist Ancel Keys demonstrated its usefulness for large-scale research and officially named it Body Mass Index. Therefore, BMI was meant for population studies, not for evaluating individual health.

The main problem with BMI is that it doesn't differentiate between fat and muscle, nor does it account for bone density, body composition, or the distribution of fat across different body compartments. Going by the BMI standards, many well-known athletes like Arnold Schwarzenegger, Serena Williams, and Dwayne Johnson would be considered overweight or obese. Meanwhile, someone with a normal BMI could still have excess visceral fat, which is most closely linked to metabolic health issues.

BMI became the standard measure in medicine mainly because it is easy to calculate. It only requires a calculator, our height, and weight. This simplicity is useful for studies of large populations but less so for individual care. That is where body composition becomes important. Body composition explains how body weight is divided among muscle, fat, bone, and water. It shows how much of our weight is related to strength and function, and how much is associated with metabolic risk and inflammation.

Imaging techniques, such as DEXA scans, can differentiate lean mass, fat mass, and bone density. Unlike BMI, DEXA shows where fat is stored—whether around the stomach, in the liver, or beneath the skin—and can track changes in muscle quality over time. Newer devices, like body composition scales, are making this level of detail easier to access. They can estimate body fat percentage, visceral fat, muscle mass, and even hydration levels at home. As these tools keep improving, becoming more accurate and more affordable, they are likely to replace traditional bathroom scales, shifting our focus from simply weight to understanding what that weight really means.

 At both the individual and population levels, newer measurements such as the waist-to-hip ratio (WHR) and waist-to-height ratio (WtHR) provide more accurate assessments of health than BMI. WHR is calculated by dividing the narrowest part of the waist (usually at the belly button) by the widest part of the hips. In a study involving more than 387,000 subjects, WHR had the strongest and most consistent association with mortality from cancer and cardiovascular diseases, irrespective of the BMI (Khan, 2023).  Similarly, keeping your waist circumference below half your height is associated with a longer lifespan and lower cardiovascular risk than BMI is. Unlike weight, waist size reflects visceral fat, which is a more reliable indicator of health.

Khan I, Chong M, Le A, et al. Surrogate Adiposity Markers and Mortality. JAMA Netw Open. 2023;6(9):e2334836.