Mounting evidences suggest that obese adolescents are at increased risk of developing NAFLD and type 2 diabetes. The authors of the study with the help of noninvasive tools determined the intrahepatic fat (IHF) content of obese adolescents to identify whether it is associated with insulin resistance and abnormal energy homeostasis. IHF content, whole body energy homeostasis, insulin sensitivity, and body composition were examined with the help of localized hepatic (1)H-MRS, indirect calorimetry, fasting-derived and 3-h-OGTT-derived surrogate indexes (HOMA2 and WBISI), and DEXA, respectively.

The study enrolled 54 obese adolescents, consisting of 24 female and 30 male with age 13 +/- 2 yr, BMI >99th percentile for their age and sex. NAFLD was seen in 30% of the individuals which was defined was as IHF content >5% wet weight. In addition, NAFLD was found to be associated with higher ALT, HbA(1c), trunk fat content, and lower HDL cholesterol. The outcome revealed that individuals with NAFLD had increased fasting plasma glucose (89 +/- 8 vs. 83 +/- 9 mg/dl) and reduced insulin sensitivity (HOMA2 and WBISI). However, parameters of insulin secretion remained similar. Their dependence on fat oxidation in the fasting state was lower (RQ 0.83 +/- 0.08 vs. 0.77 +/- 0.05), and their potential to suppress it during the oral glucose challenge was reduced in contrast to those with normal IHF content. The association between IHF content and insulin sensitivity got deteriorated, whereas the link with fasting lipid oxidation remained static, while adjusting for trunk fat content. 

The study thus, concluded that NAFLD is prevalent in childhood obesity, while presence of insulin resistance is associated with increased trunk fat content. However, it has become evident from the findings of the study that the rearrangement of whole body substrate oxidation in these adolescents found to be an independent feature.

Source: Perseghin G, Bonfanti R, Magni S, Lattuada G, De Cobelli F, Canu T, Esposito A, Scifo P, Ntali G, Costantino F, Bosio L, Ragogna F, Del Maschio A, Chiumello G, Luzi L. Insulin resistance and whole body energy homeostasis in obese adolescents with fatty liver disease. Am J Physiol Endocrinol Metab. 2006 Oct;291(4):E697-703.