A new obesity definition could nearly double U.S. obesity rates by adding waist size and body fat measures, affecting mostly older adults and Asians.

A new proposed definition of obesity could nearly double the number of U.S. adults classified as obese, raising the rate from 43% to about 70%, according to a study of over 300,000 adults. The updated criteria go beyond BMI by including waist size, body fat percentage, and imaging scans, identifying individuals with high abdominal fat despite normal BMI. The change would classify nearly 80,000 more people as obese, especially older adults and Asian individuals, and distinguishes between clinical obesity with health complications and pre-clinical stages. Researchers say the shift could improve early detection of health risks like pre-diabetes and fatty liver, though the definition is not yet official.