Many people think that dogs are entitled to be protective of their food and that growling is a natural response. However, a dog growling at a person over food can escalate into much larger issues, especially if growling is just one of many other behavioral problems. Place several small bowls of food next to each other. As your dog goes to eat one of the bowls, move one of the other bowls to the other side, but still within the dog’s reach. Keep up this repetition until the dog realizes that a human hand is no threat to his food.
~ from A Guide To Understanding Dog Behavior by Marissa Brassfield