Role of the Very Low Calorie Ketogenic Diet (VLCKD) in Patients With Non-Alcoholic Steatohepatitis (NASH) With Fibrosis

The KETONASH study is a multicenter, open-label, randomised, controlled clinical trial that will be consecutively proposed to all patients with histological diagnosis of non-alcoholic steatohepatitis (NASH) and significant hepatic fibrosis in the context of chronic metabolic liver disease (MAFLD/NAFLD). Once the inclusion criteria are confirmed and the exclusion criteria are ruled out, patients will be subsequently randomly assigned (randomisation) with a 2:1 ratio to one of the two study arms: * VLCKD Study Arm → will receive experimental diet therapy with very low-calorie ketogenic meals (VLCKD) consisting of 5 successive phases (600 - 1500 kcal/day). * LCD Control Arm → will receive standard low-calorie diet therapy, a Mediterranean-type diet in accordance with the most recent guidelines on MAFLD/NAFLD (1200-1500 kcal/day). The KETONASH study consists of an initial 4-month diet intervention phase (Visits 1-8), followed by a second 8-month weight maintenance phase (Visits 9-15). In both study arms, the intervention will be conducted through a standardised multidisciplinary approach (Physician/Dietitian/Nurse/Psychologist) aimed at weight loss through changes in dietary regimen, exercise program, and emotional support techniques. The two study arms differ in nutritional composition, types of foods, and caloric intake.