What is the major breakdown product of fat?

The major breakdown product of fat is Acetyl CoA. During the process of lipolysis, fats (triglycerides) are broken down into glycerol and free fatty acids. The free fatty acids then undergo beta-oxidation, which occurs in the mitochondria of cells. This process cleaves the fatty acid chains into two-carbon units, converting them into Acetyl CoA.

Acetyl CoA is crucial as it enters the Krebs cycle (citric acid cycle), where it plays a significant role in generating energy. Each molecule of Acetyl CoA that enters the Krebs cycle contributes to the production of ATP, carbon dioxide, and NADH, which are vital components for energy metabolism in the body.

In contrast, glucose and pyruvate are primarily associated with carbohydrate metabolism. While fatty acids can ultimately contribute to energy through the same pathways as carbohydrates, the specific breakdown product from fats is primarily Acetyl CoA, making it the correct answer in this context.