For a cereal to be considered healthy, it should have fewer than 10 grams of sugar per serving. Otherwise, it turns into a dessert breakfast. Having too much sugar in the morning will lead you to a sugar crash, and we promise this is not a pleasant experience to have as you walk into work. To keep you satisfied until lunch time, select cereals that have at least three grams of fiber per serving. The same goes for protein; cereals that have more than five grams of protein per serving will keep you full and prevent overeating later in the day.