I grabbed the food from the girl working with me during the shift
Is it the girl you work with on the same shift?  Was it her food?
Yeah, it was the girl during the shift. I grabbed the food from her and left her to find something else to eat
It is not good to steal food that doesn't belong to you and you shouldn't have left her empty handed. Even if she is not going to turn you in, somebody might see and tell on you.
I'm the main chef, why it makes me a thief?
You are still taking something that was for someone else. Why not use you chef skills to make a nice lunch for both of you?