Sorry for my late response (thank you, Interspectator, for your explanation!), the article said sometimes Yuzuru ate 3000~3500 kcal of food a day
I looked up on the internet and this site said the average calories a normal male took a day in 20's was about 2300 kcal. I've also watched the documentary of players in Synchronized Swimming before, they were persuaded to eat A LOT by their coaches, they couldn't go to bed unless finishing their meals. It seemed it was needed to their bodies because the energy consuming was huge and they had to float on the water rightfully.