Do you remember hearing that? Your mother/aunt/father had a good point. A lot of dogs have a problem with possession aggression. In other words, "what's mine is mine, and you aren't allowed to even look at it." Sharing is a foreign concept to most dogs, especially dogs who are the sole family pet. A dog with possession aggression will guard his resources, whether his resources are his food, toys, or the most valuable of all, You.
The easiest way to deal with this is to start from puppyhood. Get your dog used to having you come and take his things away. Give them back, but take them for a while. Let him see that even someone else has something he wants, if he waits patiently he'll most likely get it back.
Teaching a "give" command will also help. When your puppy has a toy in his mouth, gently take it from him, saying "give" at the same time. When you have it, reward him and praise lavishly. By rewarding him as well, he'll learn that to give something to you, means to get something even better at times.
Oops, you've left it too long, or you've adopted a dog who's got guarding tendencies. Either way, it will now take time, patience and persistence for your dog to learn that there's no need, and that it's unacceptable to try and protect his food.
The first step is to remove anything he may tend to guard. Toys, bones, food bowls, dog beds, they've all got to go. Remove his access to the furniture, whether that's by blocking him from entering from a room, or by keeping him tethered on a leash, out of reach. Absolutely everything becomes yours, to be doled out whenever you feel like it. Now you need to teach him to trade.
What does he have that always gets a mediocre reaction? A stuffed toy? A stick? It's not the greatest thing in the world, but he guards it anyway, since it can be fun to play with.
Grab yourself a handful of treats. These should be the regular "oh these are so good, I love them" treats, but not the drool-worthy uber-motivating treats like chunks of cheese, or liver biscotti. Not yet.
Well that's a no-brainer. What is better to have? A tasty treat, or a stick? As soon as that stick is let go, give him praise and treats!
Don't stop there. Keep it up! He needs to cement in his mind that when you, the ultimate Boss, come by, you'll remove whatever he has, but you might replace it with something better.
Dinnertime rolls around, and you don't really want to trade for dinner. What do you do? Dinner is a very important resource and attempts to remove it before the bowl is empty result in attempted amputation.
Or at least, not yet. Is he giving you pleading looks yet? Is he sucking in his belly to produce that emaciated look, and adopting the saddened hound-dog eyes? Okay then, now it is time.
Forget just putting the bowl down for him. Make him sit. Make him wait a minute longer. Put a very small portion of his regular dinner in his bowl. Hold on to the bowl for him to eat out of. Does he eat with your hands still on the Vessel of Chow? Very good. Before he finishes what's there, slowly pull it away. Don't get into a wrestling match over it though, if he starts to protest, use your newest command, "Trade".
Give the bowl back with more food in it. This time you can put it down for him. You want him to realize that you'll never let him starve, but you reserve the right to remove his dish. Keep this up, every day, just this, until you no longer get a resistance when you remove the bowl. On to the next phase ...
You follow the new routine, making him go through a bit of a hassle before he gets his full dinner again, but this time, instead of leaving him to eat in peace after, you put your hand on his head, and follow his movements, keeping it in place. Does he give you dirty looks, but continue eating anyway? This is good. Move your hand, just stroking his head. This in itself is a reward activity, but it may take him some time to realize that it's okay, you aren't going to steal his dinner away for good.
Once he's used to you petting him while he's eating, and he's relaxed in your company, the next step is to remove his dinner. That's right. Do what he's been afraid you'll do, right from the beginning. Take it, and turn your back on him. Put one of those drool-worthy treats I mentioned earlier right on top of his dinner, then give it back. Aha. See? Like "Trade", but you didn't give the command. Keep it up.
By using patience and persistence, rewarding the good behavior, and employing the "work for it" rules, you can turn your resource guarding dog into a dog you can pet while he's eating. Just remember ... just because you can, doesn't mean you should. Everybody deserves to eat in peace.