How do triglycerides serve as a source of energy?

Triglycerides serve as a key source of energy in the body primarily through the process of being broken down into free fatty acids. When triglycerides are metabolized, they undergo lipolysis, where enzymes break them down into glycerol and free fatty acids. These free fatty acids can then be transported into the mitochondria of cells, where they undergo beta-oxidation, producing acetyl-CoA, which enters the Krebs cycle to generate ATP, the primary energy currency of the cell.

This mechanism is particularly important during prolonged exercise or periods of fasting, when glycogen stores are depleted, and the body shifts to burning fat for energy. It is an efficient way to supply energy, as fat stores are abundant and provide a significant amount of calories per gram compared to carbohydrates or proteins. Hence, the role of triglycerides as a source of energy hinges on their capacity to be converted into free fatty acids, which can be utilized for ATP production in various tissues, especially muscle and heart.