I have learned to say, “Disculpe, fíjese que, no me cae bien,” ("Excuse me, you see, that food does not make me feel good when I eat it") or “Que rico, fíjese que, ya comí mucho antes y estoy llena, pero me gustaría llevar la comida a mi casa para más tarde. Muchísimas gracias!” (How delicious, you see, I already ate a lot before this and I am full, but I would like to take the food home for later. Thank you very much!). Fíjese que is a term most commonly used in Guatemala to respectfully decline something or an invitation to do something, but it is also used in a lot of different contexts. The first response is good for things you strongly dislike, because that way, they most likely will not offer that food to you again. The second option is helpful because it allows you to accept the food, and then you can ask a friend or family member if they would like it. This way, nothing is going to waste.
