Experts have called for a revision of the body mass index (BMI) system, proposing new criteria that could reclassify up to 25 percent more adults as obese. The current BMI framework categorizes individuals with a score between 18.5 and 24.9 as healthy, 25 to 29.9 as overweight, and 30 or above as obese, a threshold associated with increased risk of serious health issues. However, a growing consensus among international researchers suggests that BMI alone is an insufficient measure of unhealthy body fat.

Last year, a global panel of experts advocated for supplementing BMI with additional metrics such as waist circumference and weight-to-height ratio to create a more comprehensive assessment of obesity. This multidimensional approach aims to better capture variations in body composition that BMI does not account for.

In a recent study led by scientists at the University of Southern California, researchers analyzed health data from 5,642 adults across the United States using the updated criteria. Their findings revealed that over 25 percent of individuals classified as having a normal BMI actually met the revised obesity standards. Furthermore, more than half of those categorized as overweight by BMI also qualified as obese under the new guidelines.

Dr. Brian Lee, an associate professor of clinical medicine at USC, emphasized the limitations of BMI in distinguishing between muscle, bone, and fat mass. He explained that “BMI is problematic because it does not specifically measure body fat and instead reflects total body weight, which includes muscle and bone.” According to Dr. Lee, this can result in muscular individuals being labeled obese despite having low body fat, while others with a normal BMI may possess excess fat that poses health risks.

The proposed overhaul highlights the need for more nuanced tools to identify obesity accurately and tailor health interventions accordingly. As public health officials and clinicians consider these recommendations, the debate continues over the most effective ways to assess and manage obesity in diverse populations.