I'm annoyed that my roommate rearranged my food
Are you annoyed at your roommate for rearranging your food? Is something wrong with his action?
He moved all of my food in the back.
It is wrong to hide other peoples food and move them with out their permission. You should talk about house rules with them so you don't have this happen again.
What I'm supposed to do if I don't have food? I need to eat too.
You still have your food. I would talk it out, see if they even did it on purpose. From there, you can set an arrangement that works for both of you.