Please explain what an Extra is at the end of some of the Recipes. I don't understand what that means.

Foods that contribute to "Extras" include foods that have moderate to high amounts of fat or processed sugars as well as candy, soda and alcoholic drinks. Extras provide a way to account for high-calorie options from the other food groups. For example, a glass of whole milk counts as 1 dairy portion and 2 extras (because it is high in fat); whereas, skim milk is 1 dairy portion and contains no extras. We use extras to help people who are on weight control programs limit their intake of fat and processed sugars. One Extra portion contains 30 to 70 calories. For more information on Extras, please see Strong Women Stay Slim, pages 190-1.