have eyes bigger than (one's) belly
To take more food than one is actually capable of eating. I always have eyes bigger than my belly when I go to all-you-can-eat buffets! Can't finish your meal, huh? I guess you had eyes bigger than your belly! Hey, do you want some of this cake? It seems I have eyes bigger than my belly.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.