The childhood obesity prevalence has increased dramatically in the last decades, affecting more than 340 million children worldwide. This condition is the major risk factor for a set of metabolic abnormalities, also known as metabolic syndrome, a condition that reduce life expectancy by 5-20 years. Changes in the global food system, and the increased consumption of ultra-processed foods (UPFs), may have contributed to the increase in the prevalence of childhood obesity and related morbidities. The mechanisms by which UPFs might promote obesity and metabolic syndrome could be multiple and not completely identified. The Ultra-processed Food in Obesity (UFO) Project has been designed to investigate the potential associations between UPFs intake and MetS in pediatric subjects