Sometimes the brain utilizes glucose pretty quickly. As if it burns it, or to be more precise, it literally "sucks out" the glucose. And our appetite can hardly be called modest. With a weight of only 1250-1450 grams (an average of 2% of body weight), the brain takes about 20% of all calories received by the body. And what’s viral to get, our "command center" does not have any reserves - it needs a constant flow of glucose.