Try changing the types of food you eat, instead of eating less food.
You can load up on fresh veggies for almost no calories, if you don't use rich sauces or toppings on them Also, make sure you get plenty of lean protein and some "good" fats, at every meal, because protein helps keep you feeling fuller, while the fats help you to feel satisfied. Limit fruit to 1-2 servings/day, and make sure you eat whole fruit, because of the filling fiber.