Do you know the difference between serving size and portion size? The serving size is the recommended amount to eat, listed on the food label. A portion is the amount you personally choose to eat.
Sometimes you eat more than one serving, like toasting an English muffin for breakfast (one English muffin = 2 grain servings). Sometimes you may eat less than one serving, like a 6-ounce container of yogurt (a serving is 8 ounces, or one cup). The amount of each individual food you choose isn't as important as the total amount you get for the day.