Dogs learn through experiencing their environment. Reward based training takes advantage of this fact.
By rewarding a dog with food for sitting on cue for example, you are instilling a memory for a behaviour that is more likely to be repeated than with other methods. The food used must be of enough value for the dog to want to repeat the behaviour in order to receive the reward again especially in the early stages of learning.
Studies have shown that when using treats to teach a dog; dogs are quicker to pick up a new behaviour and that the behaviour is more likely to be something that will be remembered in the next training session.
Using food treats to train is certainly not the only way to train your dog. But studies have shown that dogs are much more likely to pick up and are quicker to learn a new behaviour, such as sitting, when food treats are used. If treats are used correctly, they can easily be phased out in the future.
Think about it this way; Do you go to work for free? Do you work for praise or admiration? No – you work to get paid. You may do your job because you love it, but at the end of the day, you would be unlikely to keep working if you never got paid for your hard work. Food training is an easy way to motivate your dog to learn and makes training fun for both your dog and yourself. Treats used should be small, you can even use part of your dog’s daily kibble allowance.
As your dog reliably repeats a wanted behaviour, such as sitting on cue, the food treat can be given every second or third time. Keep them guessing a little, it will make your dog more motivated to perform. Eventually stretch out the time in between treats, making sure to reward with verbal praise and/or pats in between.