How is obesity defined? Moving beyond the limitations of current measures to redefine obesity

The global obesity epidemic poses significant challenges for patients, providers, and our public health system. Early identification of patients at risk for obesity-related disease is essential to address these challenges and requires clear definitions and characterizations of obesity at all stages of disease. Reliance on body mass index (BMI) to define obesity overlooks crucial phenotypic heterogeneity and its impact on cardiometabolic risk. This review summarizes the benefits and disadvantages of current and proposed measures to characterize obesity. We summarize methods to diagnose obesity that have a greater association with atherosclerotic cardiovascular disease and mortality. These methods include anthropometric measurements, inflammatory biomarkers, dual energy X-ray absorptiometry (DEXA) and magnetic resonance imaging (MRI)-measured visceral adiposity, and cardiorespiratory fitness. We further review proposed frameworks for defining obesity and assess their ability for early and appropriate identification of patients with and without obesity-related organ dysfunction. The way we define obesity has implications for clinical diagnosis and management and can impact how third-party payors reimburse for specific interventions.