Our brain is remarkably well designed to save calories. The human brain's main job is to conserve calories to keep all of your vital organs functioning. Most of human history, we have not always had access to calories (energy). Over the eons, our brain has gotten very good at conserving calories by turning muscles off when we aren't using them. This would allow our heart, lungs and other vital organs to keep us alive and survive long enough to find our next meal. Now that we have access to LOTs of calories, our brain is still genetically wired to save calories, but that genetic wiring hasn't changed enough to realize there is a Chinese Buffet down the street.