Clinical ultrasound for the characterisation of obesity: beyond the body mass index.

Obesity is a complex and heterogeneus disease, with metabolic risk that is not solely determined by body mass index. The distribution and functionality of adipose tissue- particularly that of white adipocytes- play a critical role in the development of insulin resistance, chronic inflammation and ectopic lipid deposition. Clinical ultrasound enables direct and reproducible characterization of the major fat compartments (epicardial, hepatic, perirenal, subcutaneous and intramuscular), of preperitoneal fat as an indirect marker of visceral adiposity and muscle mass, thereby overcoming the limitations of traditional anthropometric markers. These measurements have been associated with cardiovascular risk, renal dysfunction, hepatic steatosis, frailty and hospital-related complications, even among individuals with normal weight. Furthermore, ultrasound can be employed to monitor changes in these compartments following therapeutic interventions. Given its accessibility, low cost, and prognostic value, this technique serves as a valuable tool in the comprehensive evaluation of patients with obesity in Internal Medicine settings, contributing to a more precise, individualized and efficient approach to care.