What are foods that can be used simply for filling up your stomach?

Bulky foods: Raw vegetables, unbuttered popcorn, rice cakes, water, fresh fruits. The bigger question is: why do you want to fill up your stomach? Is it to try to shut off a "hungry" signal? Is it to avoid eating? Is there some other reason, like wanting to avoid eating high-calorie foods, so that you lose weight? If you feel you need to fill your stomach, you can also do something else -- walk, yoga.