It depends on what you are already eating. If you try to aim for the basic health guidelines for your age and gender it will boost your calories. For instance- 2 teaspoons of healthy oil per day, a certain number of servings of non-fat or low-fat dairy, one or two pieces of fruit, lean protein, whole grains. I find that if I eat this way my calories stay in a very healthy range. I have the opposite problem though! I am aiming for 1200 calories a day and seem to consistently eat about 1350. Try breaking your day in to meals/snacks with a calorie/nutrition goal in mind for each one and then build on that.