I wouldn't be so hasty to say it is obvious (parent made no claims about calories).
Many top chess players have considered themselves athletes, and if you've ever tried to calculate under pressure at a board for a few hours, I'm sure you'll agree it is an exhausting activity. Fischer engaged in athletic training when preparing for tournaments, for example, to aid in maintaining mental focus (he wasn't unique).
It would be silly to say that 2400 Elo indicates you can run a four-minute mile, or that calculating 6-ply in a closed position burns the same calories as running a block. If the claim is 2400 Elo tend to have similar vascular flow in the brain to people who engage in aerobic exercise or something of that nature -- maybe?
I don't think that statement is meant to be taken literally. Playing chess takes ridiculous amounts of mental effort and that's still subjectively significant even though the brain isn't consuming more glucose. We aren't machines, our attention is limited and chess consumes vast amounts of it.
Many top chess players have considered themselves athletes, and if you've ever tried to calculate under pressure at a board for a few hours, I'm sure you'll agree it is an exhausting activity. Fischer engaged in athletic training when preparing for tournaments, for example, to aid in maintaining mental focus (he wasn't unique).
It would be silly to say that 2400 Elo indicates you can run a four-minute mile, or that calculating 6-ply in a closed position burns the same calories as running a block. If the claim is 2400 Elo tend to have similar vascular flow in the brain to people who engage in aerobic exercise or something of that nature -- maybe?