Defining disease or delaying care? A conceptual and clinical appraisal of the Lancet obesity framework

The Lancet Diabetes & Endocrinology Commission undertook the complex task of addressing limitations in existing definitions and classification of obesity. Its consensus framework moves beyond body mass index (BMI) toward direct or surrogate measures of excess adiposity and distinguishes "clinical obesity" (excess adiposity plus objective organ/system dysfunction or functional limitation attributable to adiposity) from "preclinical obesity" (excess adiposity without such evidence). The Endocrine Society (ES) recognizes the substantial effort and expertise underlying this work and its intent to improve diagnostic precision and therefore provides an independent appraisal of the framework's conceptual coherence, empirical support, operational feasibility, and implications for coverage, equity, and clinical implementation. The shift away from BMI-only screening is supported by evidence that central adiposity and fat distribution better predict cardiometabolic risk than BMI alone. Validation studies (All of Us; UK Biobank) demonstrate elevated risk among individuals classified with "preclinical" obesity and even higher risk among those with "clinical" obesity, underscoring the importance of safeguards against undertreatment in the preclinical state. At the same time, lack of standardized anthropometric measurement protocols, increased resource utilization, limited distinction between subcutaneous and visceral fat depots, and insufficient data regarding the long-term implications of obesity-related disease absence prompted the ES to pause before fully endorsing the Commission's consensus. Accordingly, we outline an evaluation framework addressing available evidence, feasibility, coverage and equity considerations, and clinical impact. We advocate harmonization with established staging systems (EOSS, EASO), explicit measurement protocols, age-, sex-, and ancestry-specific thresholds, integration of mental health and patient-reported outcomes, and policies that prevent unintended care restrictions. The Commission's reframing represents a meaningful conceptual advance; broader adoption will require practical and equitable implementation.