Final answer:
When there is not sufficient carbohydrates to completely metabolize fatty acids, these molecules form ketones. Ketone bodies can serve as a fuel source when glucose levels are too low in the body.
Step-by-step explanation:
When there is not sufficient carbohydrates to completely metabolize fatty acids, these molecules form ketones. Ketones are produced when excessive acetyl CoA is created from the oxidation of fatty acids, resulting in an overload of the Krebs cycle. Ketone bodies can serve as a fuel source when glucose levels are too low in the body, such as during prolonged starvation or uncontrolled diabetes.