The human brain accounts for about two per cent of body weight and consumes about twenty per cent of the body's total energy every day — and that consumption barely changes whether you are solving differential equations or staring at a wall - Space Daily

The number that gets repeated in pop-science columns is the 2/20 split (that the brain is 2% of body weight but consumes 20% of energy) — a small organ, enormous appetite — and I think it’s fair to suggest that many people are led to believe that “thinking” i…