"Nós estamos olhando para a comida."
Translation:We are looking at the food.
Prepostion is a delicate aspect in every language once, most of time, we don't use the same translation to the sentences. Especially for phrasal verbs. It's a bit complicated because they become different verbs in Portuguese. Take a look: look = olhar, look at = olhar para, look for = procurar, look into = examinar, look after = cuidar. So one cant set a rule about this :/