Defining "obesity" is not straightforward. Using body mass index (BMI) alone may miss some unhealthy individuals and mislabel others. New global clinical recommendations aim to improve the definition of obesity. The Lancet Diabetes & Endocrinology Commission, supported by 75 medical organizations, proposes to use objective measures of illness based on individual risk factors. Dr. Kushner states that these recommendations represent a significant advancement in recognizing obesity as a disease rather than just a risk factor, allowing clinicians to identify those in need of treatment.