Unlike other parts of the body, the brain burns its four hundred calories at a steady rate no matter what you are doing. Hard thinking doesn’t help you slim. In fact, it doesn’t seem to confer any benefit at all. An academic at the University of California at Irvine named Richard Haier used positron emission tomography scanners to find that the hardest-working brains are usually the least productive. The most efficient brains, he found, were those that could solve a task quickly and then go into a kind of standby mode.
