What are ketone bodies?

Ketone bodies are indeed a fuel source derived from fats, specifically produced in the liver during periods of low carbohydrate availability. When the body experiences a shortage of glucose, such as during fasting or prolonged exercise, it begins to break down fat for energy. This process leads to the formation of ketones, which can then be used as an alternative energy source by various tissues in the body, including the brain.

This metabolic pathway is particularly important during situations such as a ketogenic diet or extended periods of fasting, where glucose levels are insufficient to meet energy demands. Ketone bodies provide an efficient energy source, allowing the body to maintain function when carbohydrate reserves are low.

In contrast, other answer choices do not accurately represent what ketone bodies are. They either refer to the digestion of carbohydrates, stored fats, or proteins that are not related to the production of ketone bodies or their function in energy metabolism.