1. Fruit. A piece of fruit can go a long way in making you feel full and satisfying your sweet tooth. With such a wide variety, you should find a fruit that you like. Peaches, kiwis, apples and grapes are all good examples. They are low in calories and full of fiber which will slow digestion meaning you'll eat less.
2. Yogurt. Yogurt (the kind low in sugar) is high in protein and calcium. There are plenty of flavors that range from chocolate to orange and can satisfy a craving for something unhealthy.
3. Salads. Salads have a lot of volume and are very low in calories. Most vegetables are high in water and fiber content which will make you feel full for a long time. If you use salad dressing, pick one that's oil based which includes healthy fats.
4. Vegetables. Some vegetables are great snacks by themselves without a salad. Carrots and celery sticks can fill you up really quick and not add too many calories to your daily intake. You can dip them in some low-fat salad dressing for added taste.
5. Tuna. Canned tuna is a great snack. Each 6oz. can has about 150 calories (you don't have to eat it all at once) which can be split up into 2 servings. It is mostly protein with a little fat. You can top it with lemon juice, mix it with some low-fat salad dressing or eat it straight out of the can.