Relationship Between Serum β-Hydroxybutyrate and Hepatic Fatty Acid Oxidation in Individuals with Obesity and NAFLD.

NAFLD is characterized by excess lipid accumulation which can progress to inflammation (NASH), and fibrosis. Serum β-hydroxybutyrate (β-HB), a product of the ketogenic pathway, is commonly employed as a surrogate marker for hepatic fatty acid oxidation (FAO). However, it remains uncertain whether this relationship holds true in the context of NAFLD in humans. We compared fasting serum (β-HB) levels with direct measurement of liver mitochondrial palmitate oxidation in humans stratified based on NAFLD severity (n = 142). Patients were stratified based on NAFLD activity Score (NAS): NAS=0 (no disease), NAS=1-2 (mild), NAS=3-4 (moderate), and NAS³5 (advanced). Moderate and advanced NAFLD associated with reductions in liver HMGCS2, serum β-HB, but not