Begging is not an instinctive behavior. It’s learned. If you’ve succumbed to begging one time, the dog will keep begging until trained not to — and may start challenging you in other areas.

What you need is a measure of courage. If you’re watching TV with a bowl of popcorn, and your dog is nosing up to you, command, “No, no, sit.” If your dog ignores you, lock it in another room. Ignore its whining, scratching and barking, even if it persists a long time. After once or twice being sent to doggy jail, the dog will get the message.

Practice zero tolerance. If the dog gets lucky even once in begging, you’ll have to start the training all over.
Confine your dog’s eating to its regularly scheduled meals, and the occasional treat doled out as a reward for obeying a command. This means no slipping something to the dog from the dinner table, or dropping food on the floor, or letting the dog lick a plate. These actions encourage the dog to follow the scent of food right up to the table, or to your feet as you snack.

A wise strategy is to completely bar a dog from your area while you eat. You may have to crate it or put it in another room or outside until your meal is done. Another strategy is scheduling its meals at the same time as yours, so that it’s busy eating at the same time you are.