someone's eyes are bigger than their stomach
US /ˈsʌm.wʌnz aɪz ɑːr ˈbɪɡ.ər ðæn ðer ˈstʌm.ək/
UK /ˈsʌm.wʌnz aɪz ɑːr ˈbɪɡ.ər ðæn ðer ˈstʌm.ək/

1.
avoir les yeux plus gros que le ventre, prendre plus qu'on ne peut manger
to take more food than one can actually eat
:
•
He ordered three main courses, but his eyes were bigger than his stomach.
Il a commandé trois plats principaux, mais ses yeux étaient plus grands que son estomac.
•
I think my eyes were bigger than my stomach when I filled my plate at the buffet.
Je pense que mes yeux étaient plus grands que mon estomac quand j’ai rempli mon assiette au buffet.