The statement "someone's eyes are bigger than their stomach" is a common expression used to describe someone who has overestimated their appetite or capacity for food. However, there are several synonyms that can be used to convey the same meaning in a different way. One such synonym is "biting off more than one can chew," which means taking on more than one can handle. Another synonym is "overreaching," which refers to attempting to do more or achieve more than is realistic or feasible. Finally, "overextending oneself" can also be used to describe someone who has taken on more than they can handle, whether it be with regard to food or other responsibilities.