Protein shakes are typically made from soy, whey, rice, or egg, or blends of these. They come in a variety of flavors, including chocolate, vanilla, strawberry, and others. Many natural varieties use less sugar, colors, and flavors, and often contain added fiber. Some, especially those made for people using shakes as part of a fitness or weight loss program, may contain additional nutrients. Shakes may come in powdered form, or in cans or bottles, usually in single servings.