Ketogenezis

Ketogenesis is a metabolic process that occurs primarily in the liver. It is the biochemical pathway by which fatty acids are broken down to produce ketone bodies. This process is stimulated during periods of low carbohydrate availability, such as fasting, prolonged exercise, or a very low-carbohydrate diet. The primary role of ketogenesis is to provide an alternative fuel source for the body, particularly for the brain, which cannot directly utilize fatty acids for energy.

The process begins with the breakdown of fatty acids into acetyl-CoA. Under normal conditions, acetyl-CoA enters the citric acid cycle. However, when carbohydrate intake is low, the rate of acetyl-CoA production exceeds the capacity of the citric acid cycle, leading to its accumulation. The liver then converts excess acetyl-CoA into three main ketone bodies: acetoacetate, beta-hydroxybutyrate, and acetone. Acetoacetate and beta-hydroxybutyrate are the primary energy-yielding ketone bodies. Acetone is volatile and is largely exhaled. These ketone bodies are then released from the liver into the bloodstream and transported to other tissues, where they can be reconverted to acetyl-CoA and used for energy production through the citric acid cycle. Ketogenesis is a vital survival mechanism that allows the body to sustain brain function when glucose is scarce.