Resource guarding is a normal dog trait, some dogs have retained the urge to guard from their hunter ancestors.
Warning growls and snarls are the dog’s way of saying that he would like you to move away. Respect this and do not try to force the issue as this can result in a bite.
Hire a qualified trainer to teach your dog that a person’s approach while eating is a wonderful thing. Because resource guarding can develop at any time, prevention exercises are recommended for both puppies and dogs.