Yogurt contains two forms of milk protein, whey and casein, both of which have perfect PDCAA scores of 1.0. Milk proteins are also rich in a protein fraction called glycomacropeptide (GMP), which is a powerful hunger killer. Therefore, calorie for calorie, low-fat dairy foods, such as low-fat yogurt, satisfy the appetite longer than most other foods. They are also a great source of calcium.