Gluconeogenesis: How Your Body Makes Sugar from Fats and Proteins

The process of forming new sugars from fats or proteins is called gluconeogenesis. It occurs in the liver and kidneys when the body needs more glucose for energy but cannot obtain it from dietary sources.

Gluconeogenesis involves several steps:

1. Breakdown of Fats and Proteins: Fats are broken down into fatty acids, while proteins are broken down into amino acids.

2. Conversion to Acetyl CoA: Fatty acids and some amino acids are converted into acetyl CoA, which is a central molecule in metabolism.

3. Formation of Oxaloacetate: Acetyl CoA is then used to synthesize oxaloacetate, a four-carbon molecule.

4. Conversion to Phosphoenolpyruvate (PEP): Oxaloacetate is converted into phosphoenolpyruvate (PEP), a three-carbon molecule.

5. Gluconeogenesis Pathway: PEP enters the gluconeogenesis pathway, a series of enzymatic reactions that convert PEP into glucose.

The key regulatory enzyme in gluconeogenesis is phosphoenolpyruvate carboxykinase (PEPCK), which catalyzes the conversion of oxaloacetate to PEP. Gluconeogenesis is stimulated when blood glucose levels are low, such as during fasting or prolonged exercise. Hormones like glucagon and epinephrine promote gluconeogenesis by increasing the activity of PEPCK.