Low Carbohydrate Diet: The Effects on Non Alcoholic Fatty Liver Disease in Obese Teens With Metabolic Syndrome

Concurrent with the rising prevalence of childhood obesity, the co-morbid condition of non-alcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver disease among children. NAFLD is characterized by accrual of excess triglycerides (TG) in the liver that leads to inflammation, fibrosis, and cirrhosis. One-third of the pediatric population has NAFLD, a disease strongly associated with insulin-resistance and metabolic-syndrome (Met-S). NAFLD is predicted to become the leading cause of liver transplantation in adults by 2030. Current understanding of NAFLD indicates that presence of excess TG in liver is an absolute requirement for disease progression. First-line therapy for NAFLD is focused on decreasing adiposity and improving insulin sensitivity through diet and exercise. Recent adult data indicate that dietary carbohydrate-restriction is more effective at reducing hepatic TG-content than traditional calorie-restriction. Few studies have been conducted to establish resolution of hepatic steatosis by any intervention. Such studies in pediatrics are primarily limited by a need for liver biopsy. However, hepatic proton magnetic resonance spectroscopy (H-MRS) is a new innovative tool used to quantitatively measure hepatic TG content in a non-invasive manner. The primary aim is to compare the impact of dietary weight loss via carbohydrate-restriction and calorie-restriction on hepatic TG-content quantified by H-MRS in obese children with biopsy-proven NAFLD and Met-S. This IRB approved protocol is a randomized control study. The investigators will recruit subjects from the Center for Obesity and its Consequences in Health and the pediatric gastroenterology clinics between the ages of 11-17 years who meet criteria for NAFLD and Met-S. A H-MRS will be obtained in each subject prior to the start of dietary intervention. Fifty-four subjects will be randomized to either a carbohydrate-restricted or calorie-restricted diet for 6 months with no change in baseline activity. A repeat H-MRS will be compared to baseline to determine the whether dietary carbohydrate-restriction is superior to calorie-restriction for reducing hepatic TG content. The investigators believe that subjects on the carbohydrate-restricted diet will have marked decrease in hepatic TG content compared to those in the calorie-restricted diet given the same degree of reduction in body mass index.