To plenty of fitness diehards, whey protein can seem like its own food group. (Spoiler alert: It's not). But despite our long-term commitment to this protein powder, the research is ongoing. Plenty of questions still remain on what makes it so great, what is the best form to take, and what is the optimal timing for it. Grab your shaker bottle and read on to get the full scoop on whey protein.

What Is Whey Protein?

Whey comes from milk, which is actually comprised of two proteins: casein, which makes up approximately 80 percent of milk protein, and whey, which makes up the other 20 percent. When cheese is produced, whey is separated from the solid curds and can be found in the liquid that is left behind.

Once separated, it goes through several more processing steps to become what most people recognize as whey protein: a relatively tasteless powder that can be added to shakes, protein bars, or even baked goods. It's a common protein-booster in commercial smoothies, bars, cereals, and plenty of other foods, but can also be taken on its own.

Like all proteinsóchicken, beef, egg, soy, rice, hemp, and so onówhey is composed of amino acids, which the body can use for muscle growth and tissue repair. But it's whey's high concentration of branched-chain amino acids (BCAAs), especially leucine, that sets this protein apart from the others.

What Does Whey Protein Do?

For starters, whey is a complete protein, meaning it has all nine essential amino acids necessary for protein synthesis. We call them "essential" because your body can't make them and therefore you must consume in them in your diet.

Whey is particularly high in the group of three essential amino acids known as BCAAs: leucine, isoleucine, and valine. These help to build and maintain muscle mass, and can also serve as an energy source during prolonged or intense workouts.

Leucine, specifically, has been shown to have the greatest impact on rates of muscle protein synthesis, the process that makes your muscles bigger and stronger. One 25-gram scoop of whey protein has approximately 3 grams of leucine. Compare that to only 2.3 grams per scoop in casein and 1.5 grams in soy.[1] Seeing as the threshold for activating protein synthesis occurs right around 2.5 grams of leucine, whey is a no-brainer for athletes looking to boost growth, recovery, and performance.

What's the Difference Between Whey Concentrate, Isolate, and Hydrolysate?

While most people can name a benefit to supplementing with whey protein, the same can't be said about explaining the differences between the different forms of whey. Fancy names given to the different forms of whey more or less tell you how the protein has been processed and filtered.

Whey Protein Concentrate: Whey concentrate is about 80 percent protein, and typically contains slightly higher amounts of fat and carbohydrates than the other two varieties. It's still relatively low in both, although plenty of powders and ready-to-drink protein products add extra sugar and fat back in.

Whey Protein Isolate: Whey protein isolate has had all fat and lactose removed, boosting its protein concentration to 90-95 percent protein.

Whey Protein Hydrolysate: Hydrolysed whey is often referred to as "pre-digested," because it has already undergone partial breakdown. This reduces digestion time compared to the other two forms of protein. Both whey protein concentrate and whey protein isolate can be made into whey protein hydrolysate, so its protein content can vary.

Which one is the best? It would be easy to look at the list above and think that hydrolysate or isolate are far superior to simple whey concentrate. However, long-term studies have yet to show that one form is superior for muscle growth and tissue repair compared to the others, so pick the one that best fits your lifestyle and budget.

If you're after the best-tasting protein or are on a tight budget, sticking with a whey protein concentrate makes sense. The extra carbs and fat often go a long way in the flavor department. On the other hand, if you are dieting down or low-carbing it, a whey protein isolate is a popular option. If you have a mild intolerance to lactose, or suffer from GI problems every time you have a protein shake, you may want to try a whey protein isolate (which contains less lactose) or whey protein hydrolysate.

Benefits of Whey Protein

Whey Protein Can Boost the Effects of Resistance Training: Whey protein supplementation combined with resistance exercise appears to offer up greater gains in muscle strength and muscle mass over just resistance training alone. A study published in the International Journal of Sport Nutrition and Exercise Metabolism concluded that those who supplemented with whey protein during resistance training had an almost 5 percent (or 5.5 pound) greater increase in lean tissue mass compared to those who didn't supplement.[2]

And compared to other forms of protein, like casein and soy, whey reigns superior when it comes to greater improvements in muscle strength and size. Following a 10-week intense training program, resistance-trained men who supplemented with whey protein isolate had significantly greater gains in strength and lean body mass, and a decrease in body fat, compared to the group that supplemented with casein.[3]

Supports Healthy Weight Loss: Protein is known for its ability to support healthy weight loss because it's the most fulfilling macronutrient. Higher protein diets can also help boost metabolism, leading to long-term weight loss.[4]

Supplementing with whey protein is an easy way to increase your daily protein intake, and when combined with a reduced-calorie diet, may help you lose weight. In one 2008 study, obese participants who were given a whey protein supplement lost significantly more body fat and maintained more muscle mass than the placebo group.[5]

May Help Reduce Hunger: Along the lines of supporting healthy weight loss, whey protein has been shown to increase satiety and reduce short-term food intake. A 2009 study compared the effects of different protein sources on appetite and found that whey protein decreased hunger more than soy or casein.[6] Furthermore, the amount of food consumed three hours after the protein meal was lowest after the whey protein meal.

How and When to Take Whey

Before or After A Workout as A Supplement: Whey protein is commonly taken in 25-30 gram dosages, either 1-2 hours before your workout or immediately post-workout. No, you don't have to slug back a shake within a 30-45-minute "anabolic window" after a workout for it to count. Anytime within a couple of hours is probably just fine. But if the immediate post-workout ritual of having a shake helps you remember to have one, well, do it!

Delaying your intake of whey can hinder muscle growth and repair, as well as leave you feeling more sore for your next workout.

As A Dietary Protein Source: Whey makes a great appetite-curbing snack between meals, or it can be added it to your breakfast oatmeal or smoothie.

Can You Have Too Much Whey?

Too much protein can lead to some GI distress (and the dreaded protein farts), but there are no studies to suggest higher protein diets can lead to kidney damage, bone loss, or dehydration in healthy individuals.[7-9]

If you want to get systematic about your whey and avoid any digestive unpleasantness, calculate your recommended daily intake of protein, then spread your intake across several doses of 25-30 grams. For many, this is a more sustainable approach than trying to cram as much protein as possible into three meals. Once you have a daily number to aim for, a whey protein supplement and a healthy diet can be sufficient to hit your daily intake goals.

The Bottom Line

No matter if your goal is to increase muscle mass, reduce body fat, or control hunger, whey can help. No, a shake isn't a replacement for a proper nutrition and training plan, but a quality whey protein supplement can be important in helping you change your body composition and get the most out of your training.

  1. Devries, M. C., & Phillips, S. M. (2015). Supplemental protein in support of muscle mass and health: advantage whey. Journal of Food Science, 80(S1).
  2. Candow, D. G., Burke, N. C., Smith-Palmer, T., & Burke, D. G. (2006). Effect of whey and soy protein supplementation combined with resistance training in young adults. International Journal of Sport Nutrition and Exercise Metabolism, 16(3), 233-244.
  3. Cribb, P. J., Williams, A. D., Carey, M. F., & Hayes, A. (2006). The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. International Journal of Sport Nutrition and Exercise Metabolism, 16(5), 494-509.
  4. Paddon-Jones, D., Westman, E., Mattes, R. D., Wolfe, R. R., Astrup, A., & Westerterp-Plantenga, M. (2008). Protein, weight management, and satiety. The American Journal of Clinical Nutrition, 87(5), 1558S-1561S.
  5. Frestedt, J. L., Zenk, J. L., Kuskowski, M. A., Ward, L. S., & Bastian, E. D. (2008). A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study. Nutrition and Metabolism, 5(1), 8.
  6. Veldhorst, M. A., Nieuwenhuizen, A. G., Hochstenbach-Waelen, A., van Vught, A. J., Westerterp, K. R., Engelen, M. P., ... & Westerterp-Plantenga, M. S. (2009). Dose-dependent satiating effect of whey relative to casein or soy. Physiology and Behavior, 96(4), 675-682.
  7. Kerstetter, J. E., Kenny, A. M., & Insogna, K. L. (2011). Dietary protein and skeletal health: a review of recent human research. Current Opinion in Lipidology, 22(1), 16.
  8. Martin, W. F., Armstrong, L. E., & Rodriguez, N. R. (2005). Dietary protein intake and renal function. Nutrition and Metabolism, 2(1), 25.
  9. Bonjour, J. P. (2005). Dietary protein: an essential nutrient for bone health. Journal of the American College of Nutrition, 24(sup6), 526S-536S.