Final answer:
Ketone bodies are produced through the process of ketogenesis when carbohydrate availability is low, serving as an energy source and sparing protein tissues from catabolism.
Step-by-step explanation:
Ketone bodies are made from fat fragments when there is an inadequate supply of carbohydrates. During periods of fasting or starvation, when glucose levels are low, the body begins to use fatty acids and triglyceride stores to create ketones for energy.
This process, known as ketogenesis, helps spare protein tissues from being broken down for gluconeogenesis. Eventually, if fasting continues and fat reserves are depleted, the body will turn to protein catabolism for glucose synthesis, affecting muscle mass as a consequence.
However, this shift to ketone body metabolism serves as a critical energy source during prolonged periods without adequate glucose, such as in prolonged starvation or uncontrolled diabetes.