Maya at the age of 5-6 mo. growled at me while eating. My wife and I acted right away to fix it before it became a major problem.
What we did was, we did not put the food bowl down till she looked at us in the eye and sat down on her own. Then after her eating for 10-15 sec. we then would walk in front of her food till she backed off and walked away or sat down. Then we would pick it up for 5-10 seconds then repeat the first step. (Look in the eye then sit then put the bowl down)
We did it for about a week then started to touch her paw,side,head,snout, and then we were able to touch the food in the bowl while she was eating. (That point took about two to three weeks. It takes a lot of work, but I can pick the food up at any point of her eating. I can also take treats away anytime I want to. This should be done with toys as well.
I don't think it's a good idea to give treats while bad behavior is going on. I think that is saying the bad behavior is a good thing to a dog.
Another thing I should mention that we also did was use our hands to mix or touch her food so she smelled our hands on her food while she was eating. Not sure if that had anything to do with fixing the problem but it just made sense to do it.