Cauliflower, eggplant, zucchini or carrots are good options for vegetables. Almonds or other nuts are also great to get a "full" stomache feeling. Fruits are handy and make for excellent low carb fillers. If you can incorporate any of these into a soup or broth format that would be the most filling as the liquid is naturally filling.
Meats are filling and make a great snack. Chicken, beef, pork, fish, and turkey are all low in carbohydrates, and will fill you up quite nicely. Also, vegetables like carrots and celery are very low in carbohydrates.
There are many things you can eat that are both healthy for you as well as being low carb. If you want something filling, but want to stay away from carbs try some protein or any fruit or vegetable. Fruits and vegetables are filling and very good for you. Eat an apple or banana.