Diagnosis of Obesity: Beyond Body Mass Index toward Comprehensive Clinical Assessment

Obesity is defined by the World Health Organization as abnormal or excessive fat accumulation that poses a risk to health.Body mass index (BMI) remains the most practical screening tool, and Korean adults are generally classified as having obesity at a BMI of ≥25 kg/m² and abdominal obesity at a waist circumference of ≥90 cm in men or ≥85 cm in women.However, BMI alone cannot distinguish fat mass from lean mass and may not adequately reflect visceral adiposity, sarcopenia, fluid retention, or obesity-related complications.Therefore, a comprehensive diagnostic evaluation should begin with standardized measurements of height, weight, and waist circumference, followed by an assessment of weight trajectory, medication history, secondary causes of weight gain, obesity-related comorbidities, and limitations in activities of daily living.Body composition assessment, particularly dual-energy X-ray absorptiometry, may provide additional information when BMI and clinical findings are discordant, although its routine use in primary care may be limited by availability and feasibility.The recently proposed framework of clinical obesity and preclinical obesity underscores the importance of assessing both excess adiposity and its clinical consequences.This framework may complement rather than replace established anthropometric criteria by refining risk stratification and supporting individualized clinical decision-making.