As ESPN reports, it's possible to burn 560 calories in just two hours of the strategic board game. And they have the research and case studies to back it up.
In the 1984 World Chess Championship, the competition came to a standstill after Russian Anatoly Karpov had dropped 10kg over the course of the marathon 48 game tournament that lasted five months. According to commentator Maurice Ashley, "He looked like death."
Fast forward 20 years and Rustam Kasimdzhanov faced a similar fate following his champion win. He shed seven and a half kilos after six games.
This prompted researchers to investigate and in October 2018, U.S. based company Polar began monitoring the heart rates of chess players during a tournament. Astonishingly, they found that Chess weapon Mikhail Antipov had torched 560 calories in just two hours - similar to what tennis goat Roger Federer would burn in an hour of singles tennis.
Robert Sapolsky from Standford University points to breathing rates, blood pressure and muscle contractions to the rapid weight loss. Top tier players will experience similar stress responses to that of elite athletes, resulting in up to 6000 calories burnt in a single tournament.
"Grandmasters sustain elevated blood pressure for hours in the range found in competitive marathon runners," Sapolsky tells ESPN.
It all combines to produce an average weight loss of 2 pounds a day, or about 10-12 pounds over the course of a 10-day tournament in which each grandmaster might play five or six times. The effect can be off-putting to the players themselves, even if it's expected. Caruana, whose base weight is 135 pounds, drops to 120 to 125 pounds. "Sometimes I've weighed myself after tournaments and I've seen the scale drop below 120," he says, "and that's when I get mildly scared."
Now we know what we're doing in our spare time to get a six-pack...