When shopping for cereal, check the Nutrition Facts label using the Rule of Five as a guide. Ideally, cereal should have less than 5g of sugar and 5g or more of fiber per serving. The Rule of Five is not set in stone. If a cereal is very low in sugar, it's okay if it's a little lower in fiber. Oatmeal, for example, has only 4 grams of fiber per serving but 0 grams of sugar. On the other hand, cereals that contain dried fruit may be higher in sugar. Just be sure that most of the sugar is, indeed, coming from fruit and not added sugars. (If sugar or corn syrup is among the first few ingredients in the list, take a pass).