henry copeland:

Why grandmasters like Magnus Carlsen and Fabiano Caruana lose weight playing chess

In 2004, winner Rustam Kasimdzhanov walked away from the six-game world championship having lost 17 pounds. In October 2018, Polar, a U.S.-based company that tracks heart rates, monitored chess players during a tournament and found that 21-year-old Russian grandmaster Mikhail Antipov had burned 560 calories in two hours of sitting and playing chess -- or roughly what Roger Federer would burn in an hour of singles tennis.
- www.espn.com