A shake or smoothie made from protein powder has become a popular pre- and post-workout snack for many athletes. For a lot of us, it's even replaced entire meals. But what are we to make of all the varieties and sub-categories? Are any better than others?

Whey is perhaps the most common form of powdered protein. Whey is the liquid that separates from the curds during cheese-making. Clearly, whey protein should be avoided by those who are vegan or lactose intolerant. Those caveats aside, it's very popular among athletes in training because it is a quickly digested protein rich in branched-chain amino acids. One of these, leucine, plays a key role in promoting muscle growth and recovery following resistance and endurance exercise.

Other powders use casein as their main source of protein. Like whey, casein is also derived from milk, but it is digested and absorbed much more slowly than whey. Casein provides a gradual, steadier exposure of the muscles to amino acids, reducing the rate of muscle protein breakdown. Although many studies have indicated that casein appears to be more effective than soy and wheat protein — but not as effective as whey protein — at increasing muscle protein synthesis and strength, casein holds at least one significant advantage: when calories are restricted, casein protein generates twice the reduction in fat mass, gain of lean mass and increase in chest strength as whey.

Eggs are usually regarded as one of the best sources of nutritional protein, but egg protein-based powders are only made from egg whites rather than whole eggs. They have less ability to reduce appetite than casein or pea protein when consumed before a meal. Egg-based powders fill the niche of supplements for people who are lactose intolerant but favor animal protein over plant.

Pea-based protein powders are the most recent additions to this line of supplements, and they clearly target vegans or those athletes seeking to minimize their animal product consumption. A study shows that pea protein was absorbed more slowly than whey protein, but faster than casein. Muscle mass accumulation with pea protein has been shown to be equivalent to whey protein.

Rice-based protein powders have been around for a while, but lack sufficient lysine to provide you with complete protein. One study did indicate that taking 48 grams of rice protein or whey protein daily resulted in similar changes in body composition, muscle strength and recovery.

It’s important to note that not everyone will benefit from taking supplements. If your diet is already rich in high-quality protein, you likely won’t see much difference simply by adding protein powder.