Leonard and Sheldon sometimes eat breakfast cereals for breakfast.
According to Leonard, Sheldon orders their breakfast cereals according to fiber content because he claims they "have both found that helpful at times". Brand names seen in the show include Honey Puffs from the low end of the fiber shelf and Big Bran from the high fiber end ("0102"). When he is not happy he goes to the high fiber end. interestingly, it looks like Sheldon and Leonard have cereal dispensers next to the sink but, they are never mentioned or being used.