[Non-alcoholic fatty liver disease and its association with clinical and biochemical variables in obese children and adolescents: effect of a one-year intervention on lifestyle].

OBJECTIVE To study the frequency of non-alcoholic fatty liver disease (NAFLD), its relationship to clinical and biochemical variables, and the effect 12-month's lifestyle intervention in obese children and adolescents. METHODS Thirty-six obese patients aged 7 to 18 years, 42% female and 58% male, 72.2% prepubertal and 27.8% pubertal, were selected. Anthropometric measurements and glucose, insulin (baseline and after a glucose load), lipid profile, C-reactive protein, and aminotransferase tests were performed before and 12 months after dietary and physical activity intervention. Liver ultrasound was performed to determine the presence of NAFLD. RESULTS NAFLD was found in 66.7% (n=24), and was mild in 30.6%, moderate in 27.8%, and severe in 8.3%. Subjects with NAFLD had higher body mass index (BMI, p=0.007), waist (p=0.005), fat area (p=0.002), basal insulin (p=0.01), and HOMA-IR (p=0.008) values and lower QUICKI (p=0.02) values than those with no NAFLD. After intervention, physical activity increased (p=0.0001) and calorie intake remained unchanged. NAFLD disappeared in 9 patients (37.5%, p=0.02) and disease severity decreased in 3 patients (12.5%). In addition, BMI Z-score (p=0.005), fat area (p=0.0001), basal insulin (p<0.05), insulin resistance (p<0.005), lipid profile (p<0.03), and transaminases decreased. Weight loss was the main variable accounting for NAFLD improvement. CONCLUSION This group of obese children and adolescents showed a high frequency of NAFLD. The lifestyle intervention with weight reduction is effective for the treatment of NAFLD.