BMI’s Role as a Health Metric Faces Renewed Scrutiny

Recent expert recommendations and institutional statements have highlighted ongoing concerns about the use of Body Mass Index (BMI) as a health assessment tool for individuals.

BMI was originally introduced as a statistical method to study weight trends in populations, rather than to evaluate health at the individual level. Over time, however, it has been widely adopted in clinical and public health settings for screening and categorizing weight status.

One of the main limitations of BMI is its inability to differentiate between fat mass and lean mass, which can result in muscular individuals being classified as overweight or obese. Conversely, people with high levels of body fat but a normal BMI may not be identified as having health risks associated with excess fat.

The American Medical Association has stated that while BMI shows a correlation with fat mass in large groups, its predictive accuracy is reduced when applied to individuals. This limitation is further complicated by variations in body composition across different ages, ethnicities, and genders.

What the numbers show

• In January 2025, 58 experts published recommendations to augment or replace BMI
• BMI calculations rely on self-reported height and weight, which can be inaccurate
• Waist-to-height ratio has demonstrated better correlation with health risks than BMI

International experts published in The Lancet Diabetes & Endocrinology in January 2025 have recommended that clinicians use additional measurements, such as waist circumference or body fat tests, alongside or instead of BMI. These recommendations are based on research indicating that alternative metrics may provide a more accurate assessment of health risks related to body composition.

Waist-to-height ratio (WHtR) has been shown in research to better reflect fat mass and associated health risks, addressing some of the limitations presented by BMI. Unlike BMI, WHtR is less affected by factors such as age, sex, or race, making it a potentially more reliable indicator for diverse populations.

Another challenge with BMI is the reliance on self-reported data for height and weight, which can result in misclassification due to common tendencies to underestimate weight or overestimate height. This can further reduce the accuracy of BMI categories in both clinical and research contexts.

Experts recommend that BMI be used primarily as a screening tool for assessing risk at the population level, rather than as a definitive measure of individual health. Supplementing BMI with other assessments may help address its known limitations and improve the identification of health risks.

* This article is based on publicly available information at the time of writing.