A dog that guards his food creates a danger for all the people and other pets in the household. Wandering too close to such a dog while he's eating or guarding could result in an attack. A dog may start guarding his food because he has a genetic tendency toward this type of behavior, because he is required to share a food dish or because someone or something has taken his food before. Your dog can learn to accept others near him while he eats, but it takes patience.
Set up your dog's food and water dish in a quiet location. If he eats in the kitchen while you are making dinner and others are coming through for snacks or to chat, he may feel threatened. Put his dish in a quiet corner or another room, where he can take his time and eat in peace.
Learn how close you can get before your dog gets upset. Some dogs get upset if you are in the same room while they are eating, while many are fine as long as you stay 5 to 10 feet away. You want to determine how close you can get to your dog without him growling or tensing up.
Toss your dog a treat when you are as close as you can get without him becoming aggressive. Don't say anything or try to get him to leave his food; simply toss the treat, then resume what you are doing.
Repeat this process at each meal, gradually moving closer as he relaxes. Soon you should be able to drop the treat directly into his dish. At this point, when he sees you coming, he will probably look up eagerly rather than lean over to protect his food. Don't stop yet.
Ensure you've eliminated the food-guarding habit with a final step of training: Walk by and stop near your dog while he eats, but don't bring a treat. Continue doing so during his meals for a while; if he resumes guarding, you have more work to do.