From the "you've got to be kidding me" department, here is a story for your amusement. I'm not suggesting you stop doing exercise that makes you happy and healthy to think about math problems, but reading this article will burn 50 calories from rolling your eyes.
In 1984, the World Chess Championship was called off abruptly, due to the worryingly emaciated frame of Anatoly Karpov, an elite Russian player who was competing for the title. Over the preceding five months and dozens of matches, Karpov had lost 22 lbs. (10 kilograms), and competition organizers feared for his health.
Karpov's wasn't alone in experiencing the extreme physical effects of the game. While no chess competitor has experienced such profound weight loss since then, elite players can reportedly burn up to an estimated 6,000 calories in one day — all without moving from their seats, ESPN reported.