I wouldn't be so sure. The brain is responsible for about 20% of resting metabolic rate, which translates to 300-350 calories per day for the average person. 3

I wouldn't be so sure. The brain is responsible for about 20% of resting metabolic rate, which translates to 300-350 calories per day for the average person. 300 calories is about the same as 30 minutes of zone 3 cardio (70-80% max heart rate, i.e. pretty high perceived exertion). Most people in an exercise routine would only do that a couple times per week. An "overactive" brain, day in day out, could add up to more than most people deliberately exercise.