Determine when the best time is to feed your dog. You want to feed your dog at a time when there is relative quietness in the house and when the dog can relax afterward. This brings the stress levels down and allows the dog to relax more and be a less protective. Try to always feed your dog at the same time. In the ideal case that should be after you have eaten, as the alpha dogs eat first and the lower ranking pack members last.
Establish a place and a routine to feed your dog. Always feed your dog at the same place and follow a certain routine. You will imitate the alpha dog that comes back from a hunt and shares the food with the lower ranking members of the pack. Try faking that you are eating a bit first and then giving the bowl to the dog to emphasize this. Make sure that everyone in the household takes his/ her turn to establish the idea in the dog that all humans are higher ranking pack members that share food with the lowest ranking pack member. Soon your dog will understand when it is feeding time for him.
If you have several dogs in the household that are food aggressive amongst themselves, you must know who is the higher ranking member in the “dog only” part of the pack and feed them in this order. If your dogs go through a phase of re-establishing their ranks, feed them apart and out of sight of each other.
Don’t feed your dog at the dinner table while you are eating. The alpha dogs will share the leftovers after they had their fill, not before. Remember that a lot of human food is not suitable for dogs, salt can damage their kidneys. So your best method to follow is not to never feed your dog at the table.
Here are a few more simple training solutions that may help with this common situation. Make sure that your dog gets plenty of exercise. A tired dog is less likely to get aggressive then one that has way too much built up energy. Make known to your dog the proper distinction between food time/ place and other things like time for play. Give the dog the opportunity to alternate between playing and being fed.
Good luck to you, your dog and which ever training methods you take!