The more obvious conclusion, to me, is that people prefer energy-rich foods after expending more mental energy. Our brain is a major energy sink, as it consumes

The more obvious conclusion, to me, is that people prefer energy-rich foods after expending more mental energy. Our brain is a major energy sink, as it consumes about 20% of our body's energy. I'm pretty sure that after I've been thinking hard, I prefer to eat energy rich foods. Of course, as with anything related to the brain, since we understand it so poorly it's hard to say if either hypothesis is really true.