I totally agree. My personal opinion here is: 1. They're stressed and therefor eating less, especially if they're spending the daytimes of the tournament playi

I totally agree. My personal opinion here is: 1. They're stressed and therefor eating less, especially if they're spending the daytimes of the tournament playing games - hardly conducive to appetite, and in fact I expect many will avoid food purposefully to try to not get that sleepy-full feeling. 2. To a much lesser degree, increased stress == increased heartrate == increased BMR. 3. Maybe, and I hate to speculate because of the stigma (personally I don't care if chess players are doing drugs), some amphetamine use, or at least caffeine, all of which can suppress appetate further. I personally very much doubt that it's the thinking hard that's actually burning calories. Unfortunately, I can't even read the linked post! It's paywall'd.