Brain Glucose Consumption
Glucose is essentially the main source of energy for our brains. The only exception is in cases of extreme prolonged starvation in which ketones from the liver are used to keep the brain alive (this is a very bad situation to be in). Our brains don't have storage for energy so it needs a constant supply of glucose in order to function properly. And it needs a lot of it too- although the brain is only around 2% of our body weight it requires around 20% of the glucose metabolized by the body. Neurons require the most energy and the glucose is transported to the brain by GLUT3 glucose transporters. Glucose levels in the brain are essentially constant and remain the same with small exceptions during certain mental tasks. Many brain disorders are a result from abnormal glucose functioning in the brain.