Take Smaller Meals

Try to take smaller meals throughout the day rather then larger meals. If you eat smaller meals throughout the day, your metabolism will stay at a higher rate and you won't feel as hungry throughout the day.
Just having all your calories at one sitting will doom you to that hungry feeling and if you have that hungry feeling you'll be a little more apt to break your diet. If you have a series of smaller meals, you'll be able to feel slightly full at different moments of the day. There will be less time you have to "do without" and you'll feel better for it. Your body will also process smaller meals better and subsequently burn off the calories quicker.