Insulin plays a crucial role in fat storage, but when metabolically inflexible, the body struggles to access fat for energy, leading to symptoms like fatigue and headaches. Ketones, produced by the liver, serve as an alternative fuel for the brain, especially during low-carb diets or fasting. However, even in ketosis, the brain still requires a significant amount of glucose, highlighting that ketones are not the ultimate fuel source but rather important signaling molecules.
