The brain’s appetite for energy is enormous.
The brain represents only about 2 percent of most people’s body weight, yet it accounts for about 20 percent of the body’s total energy usage— about 10 times more than would be expected. When the brain is fully working it uses more energy per unit of tissue weight than a fully exercising quadricep. In fact, the human brain cannot simultaneously activate more than 2 percent of its neurons at any one time. More than this, and the glucose supply becomes so quickly exhausted that you will faint.
Medina, John. Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School (p. 20). Pear Press. Kindle Edition.
(These quickblogs are from things I read and find interesting – feel free to comment or share if you do too!) By the way the answer to how to fuel your brain better now is NOT to get some glucose from a can of soda. Exercise creates new pathways so your brain works more efficiently.