I have certainly noticed that when I am thinking constantly, I am hungrier and eat about 15% more without gaining weight. This is not a physical matter, because when I'm thinking about hard problems I don't change my physical routine-I just think while taking a shower, driving, etc. It's not particularly extreme to say that thinking hard can help you lose weight.

I know that the brain consumes glucose when thinking hard-this is related to all those studies on willpower being a physical process-but I would love to see a formal measurement of calories.