MED4Youth project aims to demonstrate how an energy-restricted Mediterranean-style diet intervention is effective against youth obesity and reveal the mechanisms through which the Mediterranean Diet exerts the beneficial effects through a holistic omics-based system biology approach.To do so, MED4Youth will carry out a clinical and Mediterranean Diet-based study with 240 teenagers (13-16 years old) from Spain, Italy and Portugal during 4 months. In the study, the effects of a Mediterranean Diet, including products such as sourdough bread, pomegranate, hummus and mixed nuts, will be compared with the effects of a conventional low-fat diet.