Increased Adipose Tissue Fibrogenesis, Not Impaired Expandability, Is Associated With Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS: It is proposed that impaired expansion of subcutaneous adipose tissue (SAT) and an increase in adipose tissue fibrosis causes ectopic lipid accumulation, insulin resistance and metabolically unhealthy obesity. We therefore evaluated whether a decrease in SAT expandability, assessed by measuring SAT lipogenesis (triglyceride production), and an increase in SAT fibrogenesis (collagen production) are associated with NAFLD and insulin resistance in people with obesity. APPROACH AND RESULTS: In vivo abdominal SAT lipogenesis and fibrogenesis, the expression of SAT genes involved in extracellular matrix (ECM) formation, and insulin sensitivity were assessed in three groups of participants stratified by adiposity and intrahepatic triglyceride (IHTG) content: 1) healthy lean with normal IHTG content (Lean-NL; n=12); 2) obese with normal IHTG content and normal glucose tolerance (Ob-NL; n=25); and 3) obese with NAFLD and abnormal glucose metabolism (Ob-NAFLD; n=25). Abdominal SAT triglyceride synthesis rates were greater (P