Some people can get all they need from food alone. But many others find it's expensive, inconvenient, or just uncomfortable to eat that much. That's when it can be helpful to use shakes, powders, and bars to help.

"Consider powders and drinks to be supplements of convenience—and use them that way," Douglas Kalman, Ph.D., recommends. "If a shake after training is the only way you're going to get protein at that time, have the shake. If you're trying to gain weight—or lose weight—and you're in a position where you'd either have a shake or miss a meal entirely, have the shake."

If you're aiming to increase your intake, a shake or smoothie is an easy way to get 25 grams per serving, or more, as a snack or alongside your breakfast. Protein powder also works surprisingly well in many recipes for cooking and baking.

In the past, shakes were something most people associated with bodybuilders or athletes. Today, they're far more common, and everybody from young people to the elderly regularly use them.