Moving Beyond BMI: The Shift to Body Composition

“But BMI is an imperfect measure because it does not directly assess body fat.”  - American Medical Association, June 2023

Body Mass Index (BMI) has long been used to assess health and optimal weight. However, its limitations have led to calls for more useful measures. The American Medical Association (AMA) highlighted these limitations last year, and many doctors now advocate for measuring body composition instead. This article explores why this shift is happening and the new tools providing a more comprehensive view of health.

Then: BMI as the sole predictor of health

In June 2023, the AMA highlighted the limitations of BMI, noting it does not directly assess body fat and can be misleading regarding the effects of body fat on mortality rates. This new policy not only recognized BMI's historical harm and its use for racist exclusion but also recommended using BMI alongside other measures like body composition, waist circumference, genetic or metabolic factors, among others. The AMA emphasized that BMI's predictability despite correlating well at the population level, diminishes on an individual level and should not be the sole criterion for determining the overall health of individuals or finding their optimal weight.

Now: the shift to body composition is happening

Body composition scanning is a technology that measures muscle mass and fat distribution in the body, offering a more accurate reflection of health compared to BMI. The shift from BMI to body composition has been gaining momentum, especially following a statement from the American Medical Association (AMA). In a recent NPR story, Dr. Richard Joseph from Brigham and Women’s Hospital described BMI as a "very crude measure" that doesn't provide much insight into underlying health.

Traditional body composition scans, such as MRI and DEXA, are considered gold standards but are typically costly and less accessible. Over the last few years, more affordable options have emerged in the market, from home bioelectric impedance (BIA) scales to in-gym devices like InBody that made body composition scanning more accessible and affordable. Additionally, recent advances in AI technology have made it possible for more accurate and precise 3D body composition scans to be done with any smartphone camera even when compared to some of the well-established BIA solutions. Several apps now allow individuals to easily and conveniently perform these scans from the comfort of their homes, providing valuable health insights without the need for specialized equipment.

We’ll be taking a deep dive into each of these new solutions for body composition scanning in the next few weeks. Stay tuned!