Proposed BMI alternative would reverse millions of obesity diagnoses
A study published Wednesday in Nature suggests that replacing body mass index with a newer framework for diagnosing obesity could change the diagnosis of millions of people — including some currently classified as having obesity who would no longer receive that diagnosis, and others who would newly qualify. The findings add evidence to a growing debate over whether BMI is too blunt to guide medical decisions.
BMI is deeply embedded in health systems worldwide, influencing regulatory decisions, insurance coverage and eligibility for some treatments. Yet it does not account for important differences in body composition or where fat is stored, and therefore may not accurately reflect the extent to which a person’s weight is affecting their health.
The proposed alternative builds on a framework introduced last year by a Lancet commission. Rather than relying primarily on a numerical height-to-weight ratio, it aims to distinguish people whose weight is already causing harm from those who face a high risk of serious health problems in the future. By incorporating present health effects, future risk and body composition, the approach could support more individualized care. At the same time, the scale of the potential diagnostic changes shows how consequential any replacement for BMI would be for patients, clinicians, insurers and policymakers.
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