Yes, its definately possible to overfeed. When I got my first axie I fed her all the time, cos she was always happy to eat.She become very, very fat, to the point she couldn't swim anymore, she was too heavy!! Oops, I learned my lesson. Its bad for their health it they are too obese. Cut down on the amount on food if your axie is starting to look too porky.
I have 3 axies, and 2 of them would like to eat all the time,so I have to control it,however one of them only eats when hungry.