Abstract

The Lancet Diabetes & Endocrinology Commission recently introduced a new definition of obesity, termed “clinical obesity.” This concept expands the traditional Body Mass Index (BMI)-based definition by classifying obesity as a disease when excess adiposity is accompanied by obesity-related organ dysfunction or functional limitations. In contrast, individuals with increased adiposity but without such abnormalities are categorized as having preclinical obesity. The Commission discourages reliance on BMI alone for assessing excess adiposity. Instead, the framework recommends a range of measures, including waist circumference, waist-to-height ratio, body composition analysis (ex. Dual-energy X-ray Absorptiometry and Bioelectrical Impedance Analysis), and visceral fat imaging. Clinical symptoms, comorbid conditions, and functional limitations are then integrated to determine whether a patient meets the criteria for clinical obesity. However, several challenges persist. First, the lack of a clear cutoff or standardized threshold for excess adiposity may create uncertainty in clinical practice. Second, it is often difficult to distinguish whether organ dysfunction is directly attributable to obesity or driven by pre-existing susceptibility. Third, although the new definition may support treatment prioritization and reimbursement decisions, it also raises concerns about the potential undertreatment of individuals categorized as having preclinical obesity. Additionally, the framework may conflict with existing clinical or policy structures for obesity management. Therefore, fully adopting this new definition requires further discussion and refinement. In particular, establishing updated, Korean-specific diagnostic and treatment guidelines for obesity is critical to ensure appropriate clinical application and policy alignment.