Lipid Oxidation

Lipid Oxidation

Lipid oxidation, also called fatty acid oxidation or beta-oxidation, is the process that breaks fatty acids down step by step inside mitochondria to produce acetyl-CoA, NADH and FADH2. These feed into the citric acid cycle and the electron transport chain to make ATP, the cell’s main energy currency. Its rate depends on hormone signals, how much fuel is available and how much energy the body needs. During fasting, fat burning rises sharply as the body switches from glucose to fat as its main fuel, a shift driven mostly by falling insulin and rising glucagon.

Fat burning in the liver is of special clinical interest in metabolic disease. When the liver takes up more fatty acids than it can burn or export (in very-low-density lipoproteins), the excess is stored as triglycerides, causing fatty liver. Boosting fat burning in liver cells can therefore cut liver fat and improve liver health. Glucagon receptor signaling strongly stimulates fat burning in the liver: it switches on key enzymes in the beta-oxidation pathway and releases stored triglycerides for energy.

Clinical Relevance to Retatrutide

Retatrutide’s glucagon receptor activity sets it apart from dual agonists like tirzepatide and is thought to drive a meaningful rise in fat burning in the liver. In phase 2 clinical trials, people on retatrutide had large drops in liver fat, and some saw their fatty liver almost fully clear. These findings fit glucagon-driven fat burning in the liver and suggest retatrutide’s glucagon component adds a metabolic benefit beyond GLP-1 and GIP receptor activation alone.