Teaching your dog to "ask" for food by barking seemed like a good idea at first. But, now that he barks every time you sit down to a meal, grab a snack, or go to put food in his bowl, the charm has worn off. The official name for this type of barking is "on demand barking", which is when your dog barks in response to a specific stimulus. There are many ways for your dog to pick up this habit, feeding him as above is one of the more common ways.
Picture this, Jane is sitting down at the dinner table when her pup starts to bark excitedly for whatever reason. So, to get him to stop barking, Jane tossed him something off her plate as this seemed to be the easiest way to shut him up. Dogs have a habit of learning very quickly, especially when there appears to be a reward in the form of food. When Jane does this three or four times, the behavior will be firmly entrenched in his habit.
Now that your dog has developed the habit of barking or "asking" for food, you have to break him of this habit. The bad news is that it is far harder to break him of the habit than it was for him to acquire it. The longer you wait, the harder this habit will be to break. The good news is that if you are willing to put in the time and effort to train him, your pup will no longer bark at you every time you have food. The simplest command to use for this is 'quiet', try not to use anything too complicated as doing so will only serve to confuse your dog and make training him to be that much tougher.
Once you teach him this behavior, you will be able to apply the same training to any other time your dog barks and shouldn't. This includes barking at people or cars going by, people knocking on the door or ringing the doorbell. There are many things that can lead to "on demand barking", the hard part is trying to determine the various triggers so that you can work on teaching your pup to be quiet.
Before you can get started, you need to identify when your dog barks. Is it while you are sitting down to a meal, when you are on the couch with a snack, or when you are trying to feed him? Once you understand the triggers, it will be much easier for you to teach him to stop barking. However, you will need a few things, including:
Once you know when and where he is barking, training him to be quiet won't be that hard. In no time at all, you will be able to sit down to a meal or a snack and not have to listen to your dog barking at you.