In non-alcoholic fatty liver disease (NAFLD), hepatic steatosis is intricately linked with a number of metabolic alterations.
Dr Ilaria Croci and colleagues from Australia studied substrate utilization in NAFLD during basal, insulin-stimulated and exercise conditions, and correlated these outcomes with disease severity.
The team assessed 20 patients with NAFLD, and 15 healthy controls.
Respiratory quotient, whole-body fat (Fatox) and carbohydrate (CHOox) oxidation rates were determined by indirect calorimetry in 3 conditions, including basal, insulin-stimulated, and exercise.
Severity of disease and steatosis were determined by liver histology, hepatic Fatox from plasma β-hydroxybutyrate concentrations, aerobic fitness expressed as Graphic , and visceral adipose tissue (VAT) measured by computed tomography.
Within the overweight/obese NAFLD cohort, basal respiratory quotient correlated positively with steatosis, and was higher in patients with NAFLD activity score (NAS) ≥5 vs <5.
The research team found that both results were independent of VAT, % body fat and BMI.
Compared with the lean control group, patients with NAFLD had lower basal whole-body Fatox, and lower basal hepatic Fatox.
The team noted that during exercise, the patients achieved lower maximal Fatox, and lower Graphic than controls.
The researchers observed that Fatox during exercise was not associated with disease severity.
Dr Croci's team concluded, "Overweight/obese patients with NAFLD had reduced hepatic Fatox and reduced whole-body Fatox under basal and exercise conditions."
"There was an inverse relationship between ability to oxidise fat in basal conditions and histological features of NAFLD including severity of steatosis and NAS."