Grandmasters in competition are subjected to a constant torrent of mental stress. That stress, in turn, causes their heart rates to increase, which, in turn, forces their bodies to produce more energy to, in turn, produce more oxygen…Stress also leads to altered — and disturbed — sleep patterns, which in turn cause more fatigue — and can lead to more weight loss.

Read full article: ESPN.com, “The grandmaster diet: How to lose weight while barely moving.”