The brain consumes 20 percent of your body's energy, but what for? Turns out a third of the energy is spent on "housekeeping":
A new study in Proceedings of the National Academy of Sciences USA indicates that two thirds of the brain's energy budget is used to help neurons or nerve cells "fire" or send signals. The remaining third, however, is used for what study co-author Wei Chen, a radiologist at the University of Minnesota Medical School, refers to as "housekeeping," or cell-health maintenance…
"Housekeeping power is important for keeping the brain tissue alive," Chen says, "and for the many biological processes in the brain," in addition to neuronal chats. Charged sodium, calcium and potassium atoms (or ions) are continuously passed through the membranes of cells, so that neurons can recharge to fire. ATP supplies the energy required for these ions to traverse cell membranes. Chen says there must be enough energy to maintain a proper ionic balance inside and outside cells; if too many get stuck inside, it can cause swelling, which can damage cells and lead to strokes and other conditions.