Breakdown of Zjem cokolwiek, jestem głodny.
być
to be
głodny
hungry
zjeść
to eat (perfective)
cokolwiek
whatever
Questions & Answers about Zjem cokolwiek, jestem głodny.
How do I decline cokolwiek in this sentence?
The word cokolwiek is formed by adding the suffix -kolwiek to co (what). When declining it, you only change the first part. In this sentence, the verb zjem requires its object to be in the Accusative case. Since the Accusative of co is just co, the word remains cokolwiek. If you needed a different case, like Instrumental, it would become czymkolwiek.
Could I use nic instead of cokolwiek to mean "anything" here?
No, and this is a common trap for English speakers! Polish uses double negatives, so if the sentence was negative (meaning "I won't eat anything"), you would use nic and say nic nie zjem. Because this is a positive sentence emphasizing "anything at all, it doesn't matter what", you must use cokolwiek.
Why use zjem instead of jem or będę jadł?
Zjem is the perfective future tense of the verb jeść (to eat). It emphasizes the result: you will complete the action of eating whatever food you get. Będę jadł (imperfective future) would focus on the process of eating, which sounds unnatural here, while jem simply means you are eating right now.
What would change if a woman were saying this?