Differential metabolic risk factors of early nonalcoholic fatty liver disease in male adolescents with obesity and non-obesity prior to adulthood

Background: As is the case for metabolic syndrome, the incidence of nonalcoholic fatty liver disease (NAFLD) in adolescents is increasing worldwide; however, few studies have assessed metabolic differences of NAFLD between adolescents with obesity and non-obesity. Our aim was to assess metabolic risk factors of NAFLD in male adolescents with obesity and non-obesity.Methods: A total of 108 male university students (body mass index, BMI < 23, n = 24; BMI 23–24.9, n = 39; BMI ≥ 25, n = 45) who underwent the first-year health checkup were enrolled, and diagnosed with NAFLD or non-NAFLD using the abdominal ultrasonography (AUS). The relationship between NAFLD and metabolic parameters was examined based on BMI and AUS scores.Results: Metabolic parameters including hypertension, abdominal fat, liver damage, dyslipidemia, and impaired glucose tolerance were significantly increased in students with obesity (BMI ≥ 25) compared to students with non-obesity (BMI < 25), and these parameters positively correlated with BMI. AUS scores positively correlated with BMI, and metabolic parameters of NAFLD were influenced by BMI. Therefore, the parameters of NAFLD in adolescents with obesity and non-obesity were separately examined. In univariate and multivariate analyses, the alanine aminotransferase (ALT) level was significantly increased in adolescents with obese NAFLD, and the fatty liver index (FLI) and consumption of soft drinks were higher in adolescents with non-obese NAFLD.Conclusions: The metabolic risk factors of male adolescents with obese and non-obese NAFLD differ. Our findings suggest that male adolescents with obesity and non-obesity must be separately investigated when identifying adolescent NAFLD.