Does insulin-resistant fat tissue drive a cascade toward liver fat and atherogenic lipids?

Insulin-resistant adipose tissue can initiate a biologically coherent metabolic cascade linking excess fatty-acid release with hepatic triglyceride handling, atherogenic lipoprotein remodeling, and steatosis. The strongest evidence concerns fatty-acid flux, hepatic triglyceride synthesis, and liver-fat accumulation; the LDL-particle and ALT portions are less direct.

Clinical and metabolic evidence

• Insulin normally suppresses adipose lipolysis. With adipose insulin resistance, this suppression is impaired, increasing circulating non-esterified fatty acids available to the liver. In people with high versus low liver fat, insulin-mediated NEFA suppression was 57% versus 69%.
• Plasma fatty acids are a major substrate for hepatic triglyceride: stable-isotope studies indicate >60% of hepatic triglyceride may derive from plasma fatty acids; estimates in postabsorptive healthy participants were ~49% from plasma-fatty-acid re-esterification versus ~4% from de novo lipogenesis.
• In classic NAFLD, adipose-derived NEFA supply roughly 60% of liver triglyceride. Steatosis develops when fatty-acid delivery and synthesis exceed oxidation and VLDL export.

Lipoprotein mechanisms

• Greater hepatic fatty-acyl-CoA availability promotes triglyceride synthesis and secretion of triglyceride-rich VLDL.
• VLDL can exchange triglycerides for cholesteryl esters with LDL and HDL via CETP. Hepatic-lipase remodeling then favors cholesterol-poor small dense LDL and accelerates catabolism of triglyceride-enriched HDL, lowering HDL-C.
• This explains the characteristic insulin-resistant pattern, although direct human studies tracking liver fatty-acid flux through to LDL particle size remain limited.

Liver enzymes

• Liver fat and ALT may rise together (in a small obesity cohort, MRI-PDFF and ALT correlated, r=0.478), but ALT reflects hepatocellular injury, not liver fat specifically. Normal ALT does not exclude steatosis or more advanced liver disease.

Bottom line

• The claim is substantially supported: adipose insulin resistance increases fatty-acid delivery to the liver, driving hepatic triglyceride production and liver fat, with credible VLDL-mediated pathways toward lower HDL-C and smaller LDL. ALT elevation is possible but should not be attributed to steatosis alone.