Whey Protein: The Complete Guide

Whey is a type of protein derived from milk during cheese production. It is a complete protein that provides all the essential amino acids your body needs to function.

Whey protein is a popular dietary supplement among fitness enthusiasts, athletes, and bodybuilders to increase muscle mass, improve athletic performance, and support post-workout recovery.

In this article, you will find everything you need to know about whey protein.

What is Whey Protein?

Whey is one of the two primary proteins found in milk. The other is called casein.

  • Whey is rapidly and easily digested and absorbed by the body. It is ideal for enhancing muscle protein synthesis and is popular as a protein shake for muscle recovery after a training session.
  • Casein is slowly absorbed over a more extended period. It also stimulates muscle protein synthesis, but in a less pronounced and more prolonged fashion.

Where Does Whey Protein Come From?

Whey protein comes from milk. The milk from all animals that produce breast milk contains whey.

Regular cow’s milk contains about 20% whey, while the rest of the protein content is casein.

The milk proteins of other animals have different ratios of whey to casein.

Goat’s milk, for example, contains more whey and less casein than cow’s milk. The milk from our horned friends contains around 60% casein and 40% whey.1

In this article, we are talking about whey protein from cow’s milk.

Whey protein is a byproduct of the cheese-making process, where the liquid portion of the milk separates from the solid curds. The liquid whey is then filtered and processed to create a powdered form of the protein.

In regular foods, you can only find whey in dairy products like milk, yogurt, certain cheeses, and whole foods where milk is one of the ingredients.

Whey protein supplements are food in powdered form. For example, the European Commission for Health and Food Safety considers them to be “food intended for

Different Types of Whey Protein

Whey protein supplements are available in three primary forms: concentrate, isolate, and hydrolysate.

They all come from regular cow’s milk but are manufactured using different methods and filtering techniques and consist of various amounts of protein by weight.

Whey Protein Concentrate

Whey concentrate is the most common and popular type of whey protein. It is also the least processed and has an affordable price.

Whey protein concentrate contains a lower percentage of protein and higher levels of lactose and fat.

The protein content of whey concentrate is typically between 70–80%. Concentrates with a lower percentage of protein are often used in the food industry.3

Making a protein shake using whey concentrate turns out thicker than using an isolate. Many also prefer the taste of concentrate, likely because of the higher sugar and fat content.

Whey Protein Isolate

Whey protein isolate is the purest form of whey protein with a high protein content of at least 90 grams per 100 grams of dry weight.4

Isolate is processed to remove most of the lactose content and other non-protein components. 

Even if you can’t use whey concentrate because of lactose intolerance issues, you can probably use whey isolate protein powder since almost all of the milk sugar is removed during the processing.

Whey isolate is the type of whey most often used in strength training research and scientific studies examining the effects of protein on muscle protein synthesis, muscle growth, and weight loss.

Whey Protein Hydrolysate

Whey protein hydrolysate is a form of whey protein that has been partially broken down, making it easier for the body to absorb.

It is produced through hydrolysis by breaking down the long chains of whey protein into smaller peptides. This process involves using enzymes or acids to cleave the protein chains, resulting in a mixture of peptides and free amino acids.

Since hydrolyzed whey protein is already broken down, your stomach doesn’t have to do as much work, allowing for even faster absorption than whey isolates. Some people find that whey protein hydrolysate is easier on their digestive system than other whey protein forms.

While whey concentrates and isolates can have a good taste from natural (like cocoa powder) or artificial flavors, whey hydrolysate tastes bitter because the protein is already chopped up and pre-digested. Amino acids have a naturally unpleasant taste, and compared to whey concentrate or isolate, that taste is harder to disguise using artificial sweeteners and flavoring agents.

Whey protein hydrolysate is generally more expensive than other forms of whey protein.

Which Type of Whey Protein is Right for You?

The best type of whey protein for you depends on your specific needs and goals.

All three types of whey are excellent protein sources for reaching your daily protein goals and building muscle mass.

There is no evidence that any particular variant gives you better results in the form of muscle mass and strength.5

Whey protein concentrate is a good choice if you are looking for a budget-friendly, high-quality protein source.

Whey protein isolate may be a better option if you are lactose intolerant or trying to minimize your fat intake.

Whey protein hydrolysate may be the best choice for rapid protein absorption or if you have trouble digesting whole proteins. Using a hydrolysate is no more effective for building lean muscle mass, although some studies suggest that it could improve muscle recovery a bit faster than whey isolate.6 7

The three options have virtually identical effects on your lean muscle mass.

  • The protein content of whey isolate and hydrolysate is higher, so you can use less.
  • On the other hand, concentrate is less expensive, so you can use more of it without paying more.

In general, all three forms of protein can help you reach your fitness goals when consumed as part of a healthy lifestyle with a balanced diet and resistance training.

Read more:

>> Whey Protein Concentrate vs. Isolate: What’s The Difference?

Whey Protein and Muscle Protein Synthesis

To build muscle, you need to provide your body with enough amino acids, the building blocks of protein, to support muscle protein synthesis (MPS). When MPS exceeds muscle breakdown over time, you gain lean muscle mass.

When amino acids from a protein-rich meal or a protein shake appear in your bloodstream, they tell your body to flip the MPS switch and create new muscle tissue.

Whey protein is particularly effective. It is a rich source of the amino acid leucine, known to kickstart muscle protein synthesis.

Once leucine triggers MPS, your body needs all nine essential amino acids to make meaningful amounts of new muscle tissue. Unlike branched-chain amino acid supplements (BCAAs), whey contains abundant amounts of all nine. 

In addition, whey protein is rapidly absorbed by the body, allowing amino acids to quickly flood your bloodstream and creating a powerful boost in MPS, more so than other proteins.

whey protein vs casein protein vs soy protein

On the other hand, while the stimulation of muscle protein synthesis from whey protein is powerful, it is also short-lived. In less than three hours, your MPS is back where it was before you drank your whey shake.

Building Muscle with Whey Protein

Strength training builds muscle, but you must also ensure your nutritional needs are met and eat enough calories and protein to support your efforts in the gym.

Building muscle is like a house. Lifting weights lays the foundation. Then you provide the building materials with your food.

Whey protein primarily builds muscle by helping you meet your protein needs.

For optimal gains in muscle mass, you want at least 1.4 grams of protein per kilogram (0.65–0.91 grams per pound) of body weight per day.8

If you don’t get that amount of protein from your regular diet, adding one or more whey protein shakes will help you gain muscle.

However, if your diet provides you with more than 2 g/kg/day of protein just through regular foods, adding even more with whey protein shakes will likely do nothing. It’s not harmful, but you won’t gain additional muscle. Your body can only use so much daily protein for building muscle.

Compared to other types of protein like soy, research shows similar gains in muscle mass, although some studies suggest a slight edge for whey.9 10

In fact, a 2019 review concluded that whey protein supplementation is a “valid nutritional strategy for maximizing muscle mass gain.”11 As long as you don’t already meet your protein needs for muscle gain. In that case, additional protein from any source is unlikely to offer further benefits.

In summary:

  • Whey protein is a convenient and inexpensive way to boost your protein intake to build muscle.
  • Consuming whey protein alone won’t necessarily build muscle.
  • Combined with a balanced diet and regular, progressive strength training, supplementing with whey protein is an excellent way to provide your body with protein of very high quality to promote muscle protein synthesis and growth.

Whey Protein and Weight Management

Whey protein is helpful for weight management and losing body fat by increasing fullness and reducing overall calorie intake.

Protein is the most satiating macronutrient, more so than fat and carbs.12

It also has a higher thermic effect than fats or carbohydrates, which means your body burns more calories digesting and metabolizing it.

In other words: a high-protein diet will increase your energy expenditure, decrease your appetite, and make you spontaneously eat less without even thinking about it.

A meta-analysis demonstrated that you could improve your body composition and increase muscle gain and fat loss if you engage in resistance exercise and use whey protein shakes as meal replacements for other sources of calories.13

On average, the participants lost 4.2 kg of body weight and 3.7 kg of body fat, and many of them increased their lean muscle mass at the same time.

In summary:

  • Whey protein can be a helpful supplement for weight loss.
  • It’s not a magic bullet; consuming whey protein alone will not make you lose weight.
  • However, as part of a calorie-restrictive diet, it is a helpful tool for weight loss. When combined with a resistance training routine, whey protein can help prevent muscle loss or even increase lean mass during weight loss.

Health Benefits of Whey Protein

While whey protein is ideal for athletic purposes, it also offers several health benefits due to its rich amino acid profile, bioavailability, and ease of digestion.

Concentration is the better option if you’re looking for the health benefits of whey protein, as it retains the bioactive micro fractions responsible for the effects.

Immune System Support

Whey protein contains immunoglobulins, lactoferrin, and a multitude of other components which support your immune system.

Blood Pressure Management

Some studies suggest that whey protein supplementation may help combat high blood pressure in people with hypertension.


Whey protein works as an antioxidant. Numerous studies show that consuming whey can reduce oxidative stress.14

Blood Sugar Control

Consuming whey protein helps moderate blood sugar levels by stimulating the release of insulin from the pancreas and slowing glucose absorption.

It also improves insulin sensitivity, making your body more efficient at using insulin to lower blood sugar levels.

Bone Health

Whey protein is a good source of calcium, an essential nutrient for maintaining strong bones and preventing health conditions like osteoporosis.15

Cardiovascular Disease

Whey protein improves several risk factors for heart disease.16 According to the researchers, the change “is modest but may have important implications for public health.”

In another study, a daily addition of whey protein significantly reduced LDL cholesterol, the “bad” cholesterol.17

General Metabolic Health

According to a review published in the Nutrition & Metabolism journal, whey protein supplementation can help prevent declining metabolic health when combined with lifestyle changes.18

When Should You Take Whey Protein?

Whey protein is simply food in powdered form. You don’t have to treat it with any kind of particular respect, and you can use it like any other protein source in your diet to reach your target protein intake.

That means you can use whey protein at any time of the day, depending on your goals and preferences. 

Here are some general suggestions:


Consuming whey protein after a workout can help your muscles recover and grow. Numerous studies show that whey is a great option to give your body the amino acids it needs to build muscle tissue after weight training.

Whey Protein after Workout for Muscle Growth


Whey protein before training offers the same benefits as after working out.19 The timing of your whey shake doesn’t seem to matter and has similar effects on muscle strength and size whether you gulp it before or after your training session.

Between Meals 

Mix a scoop of the powder with your beverage of choice, and you’ve got a convenient snack with a great taste between meals to help you meet your daily protein requirements. 

As a Meal Replacement

If you’re in a rush or don’t have time to prepare a meal, whey protein can provide a quick and convenient source of protein. As long as your regular food intake consists of balanced meals, a whey-only meal can be a good idea to tide you over.

In summary:

  • The most common way to use whey protein is almost certainly before or after a workout to give your muscles what they need when they need it.
  • However, there is no evidence that immediately consuming protein following your workout builds more muscle compared to an hour or so later.20

There is no rush if you don’t want there to be. 

How Much Whey Protein Should You Take?

How much whey protein is too little and how much is too much?

  • If you consume too little whey protein per serving, you won’t get the maximal anabolic effect.
  • If you consume more than your body’s ability to utilize protein for muscle building purposes, it uses the excess for energy.

When you eat or drink protein, your body builds muscle through muscle protein synthesis (MPS).

The amino acid leucine triggers muscle protein synthesis. You need at least three grams of leucine per serving to maximize MPS.21

Whey protein is especially rich in leucine compared to other proteins. You only need ~25 grams of whey protein to get three grams of leucine. You’d need 30–40 grams of plant-based proteins like soy or pea to get similar amounts.

Research shows that 20–25 grams of whey per serving gives you enough protein to maximize muscle protein synthesis, both at rest and after a workout, if you’ve trained one or two muscle groups.22

After a workout session where you train several muscle groups, your muscles can benefit from more whey protein.

After a full body workout, 40 grams of whey protein stimulates muscle protein synthesis to a greater degree than 20 grams.23 A double dose doesn’t mean double the effect, but enough to justify using an extra scoop.

Older adults need more protein per serving to maximize MPS. If you’re 50 or older, 40 grams of whey protein is a good idea for the best results, especially after working out.24

In summary:

  • Taking 20-30 grams of whey protein per serving is sufficient for most people. 
  • To be safe, you can use 30 grams per serving or 40 grams if you’re over 50. Nothing terrible happens, and you ensure your muscles get as much protein as they need to grow.
  • Remember that 30 grams mean 30 grams of protein, not 30 grams of protein powder. Whey protein powder is not 100% pure protein, regardless of type. If you use a whey concentrate with 80% protein, you’d need 38 grams of powder to get 30 grams of protein.

Whey Protein for Men and Women Over 50

Whey protein can be particularly beneficial for older people for several reasons.

  • Older people may need 50% more protein than younger adults for muscle health.25 Whey protein can be an easy and convenient way to meet those needs. 
  • As we age, our muscles don’t respond the same way to protein. Research shows that whey protein is superior to a slow protein, like casein, for boosting muscle protein synthesis in older lifters.26

The uniquely fast digestion and absorption and the abundance of essential and branched-chain amino acids (BCAAs) of whey protein supplements make them stand out as the best protein powders for men and women over 50.

Read more:

>> The Best Protein Powder for Men and Women Over 50

Side Effects and Safety of Whey Protein

Whey protein is a safe supplement. There are no harmful side effects reported in the scientific literature.27

That being said, some people might experience adverse effects if they use whey protein.

Lactose Intolerance

Whey protein is high in lactose, which many people have difficulty digesting. Depending on your sensitivity, consuming whey protein can lead to digestive issues such as bloating, gas, and diarrhea.

If you are lactose intolerant, you have several options.

  • Use whey isolate instead of whey concentrate. Whey isolates are more thoroughly filtrated, contain minimal lactose, and usually work for anyone who isn’t severely intolerant.
  • Consume a lactase enzyme supplement before drinking a whey protein shake or use a whey protein with added lactase enzymes.
  • Use an alternative, non-dairy protein source, such as pea, egg white, beef, or soy protein.

Some people experience bloating, excess gas, and nausea from whey protein, even though they have no issues with lactose. In that case, look for a whey with added digestive enzymes to improve the breakdown and absorption of the protein.

Milk Allergy

Whey protein is not for you if you are allergic to dairy proteins.

Milk protein allergy is potentially dangerous, and if you are allergic to whey protein, it’s a bad idea to try to use it anyway.

Look for an alternative like soy, beef, or pea protein.


There is some evidence to suggest that whey protein may be a risk factor for acne.

Whey protein triggers a significant release of insulin and growth factors like IGF-1, which are linked to acne.28 Great for muscle growth but less terrific if you are susceptible to acne.

If you notice acne flare-ups when using whey protein, look for an alternative protein supplement. 

Heavy Metals

Some protein supplements are contaminated with heavy metals. A recent report found that 40 % of the 133 protein powder products tested had elevated levels of heavy metals. 

Fortunately, scientific analysis suggests that a typical intake of protein supplements will not result in adverse health effects due to heavy metals.29

Whey protein isolate, in particular, contains the least heavy metals, especially compared to a plant-based protein powder. If you want the cleanest proteins possible, isolates might be the way to go, possibly due to the removal of heavy metals during whey protein processing.

High-Protein Diets: Are They Safe?

As for a high protein intake in general, no Tolerable Upper Intake Level for protein consumption has been established, and no adverse consequences (including cancer, kidney disease, kidney stones, and osteoporosis) of high protein intakes have been identified.30

If you already have certain medical conditions, like decreased kidney function, you should get professional medical advice before using whey protein. But whey protein will not cause any such issues.

Frequently Asked Questions (FAQ)

Quick questions, rapid answers: let’s do some Q&A!

how much whey protein: protein supplements

Is It OK to Drink Whey Protein Every Day?

Yes. Your body needs protein daily for growth and repair, and whey is an excellent and healthy source of all the building blocks your muscles require.

What Supplements Should I Take Besides Whey Protein?

Whey protein works well with any other dietary supplement but is especially useful for increasing muscle mass when combined with creatine monohydrate.11

Do I Need BCCAs When I Use Whey Protein?

No. Whey protein naturally contains abundant amounts of all the BCAAs your body needs.

Read more:

>> Whey Protein vs. BCAA: Which is Better?

Is Whey Protein Safe During Pregnancy?

Whey protein is generally considered safe while pregnant. Research shows that whey protein during pregnancy might even reduce the risk of low birth weight.31

A healthy, balanced diet is more important than ever during pregnancy, but nothing suggests that whey protein is bad or harmful for the mother or the baby.

What Happens If I Drink Too Much Whey Protein?

Two primary things happen if your overdose on whey protein:

  • Your body uses the excess for energy instead of building muscle.
  • Your wallet gets thinner.

There is no set Tolerable Upper Intake Level for protein consumption, and whey protein is no more or less good or bad than other proteins in this regard.

Exceptionally high doses of whey protein might be wasteful but not harmful.

Final Words

You’ve reached the end of our guide on whey protein. Let’s summarize!

  • Whey is a complete protein with a very high nutritional value. Whey protein contains large amounts of all nine essential amino acids, the building blocks of protein your body cannot produce, making it ideal for supporting muscle growth and repair.
  • There are three primary types of whey protein: concentrate, isolate, and hydrolysate. They all come from milk from dairy cows. Whey protein concentrate contains varying amounts of fat and carbohydrates, while whey protein isolate has had most of the fat and carbohydrates removed, making it the purest form of protein. Whey protein hydrolysate is a predigested form of whey protein that is more easily absorbed by the body but don’t expect a good flavor.
  • Whey concentrate might be the best overall choice for most people. It builds as much muscle as the other types and costs much less. If you’re lactose intolerant, whey isolate is the better option.
  • Twenty-five to 30 grams of whey protein per serving ensures you get enough essential amino acids to support muscle protein synthesis and growth. After a full-body workout, or if you are over 50, you can utilize 40 grams per serving for muscle-building purposes.
  • Whey protein is safe, without any known harmful side effects, unless you’re allergic to dairy proteins. 
  • You can use whey protein as any other regular protein source as part of a healthy diet. After a workout, as a convenient snack, or to boost the protein content of any of your regular meals: whey protein is always a quality source of protein.
  • Whey protein has a unique combination of an almost perfect amino acid profile, fast digestion and absorption, high BCAA content, and bioactive peptides.

Whether you get it from regular dairy products like milk, protein powders, or protein bars, or use it to fry up some chocolate peanut butter protein pancakes, whey is an excellent choice of protein supplement for supporting muscle growth, recovery, and overall health.


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  2. European Commission Directorate General for Health and Food Safety. Study on food intended for Sportspeople.
  3. Journal of Dairy Science, November 2005. Volume 88, Issue 11, Pages 3826–3839. Characterization of Dried Whey Protein Concentrate and Isolate Flavor.
  4. Journal of Dairy Science, November 2005. Volume 88, Issue 11, Pages 3826–3839. Characterization of Dried Whey Protein Concentrate and Isolate Flavor.
  5. Nutrients 2019, 11(9), 2047. Comparative Meta-Analysis of the Effect of Concentrated, Hydrolyzed, and Isolated Whey Protein Supplementation on Body Composition of Physical Activity Practitioners.
  6. Journal of the American College of Nutrition. Volume 36, 2017 – Issue 1. Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males.
  7. Journal of Science and Medicine in Sports, January 2010. Volume 13, Issue 1, Pages 178–181. Supplementation with a whey protein hydrolysate enhances recovery of muscle force-generating capacity following eccentric exercise.
  8. Journal of the International Society of Sports Nutrition, Volume 14, Article number: 20 (2017). International Society of Sports Nutrition Position Stand: protein and exercise.
  9. Int J Sport Nutr Exerc Metab. 2018 Nov 1;28(6):674-685. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise.
  10. J Am Coll Nutr. 2013;32(2):122-35. Whey protein supplementation during resistance training augments lean body mass.
  11. Nutrition and Dietary Supplements Volume 11:37-48. Whey protein supplementation and muscle mass: current perspectives.
  12. The American Journal of Clinical Nutrition, Volume 87, Issue 5, May 2008, Pages 1558S–1561S. Protein, weight management, and satiety.
  13. Journal of the American College of Nutrition. Volume 33, 2014 – Issue 2. Effects of Whey Protein and Resistance Exercise on Body Composition: A Meta-Analysis of Randomized Controlled Trials.
  14. Free Radic Res. 2019;53(sup1):1136-1152. Whey proteins: targets of oxidation, or mediators of redox protection.
  15. Journal of Clinical Densitometry, Volume 21, Issue 4, October–December 2018, Pages 597-598. Impact of Whey Protein on Bone Mineral Density: a Systemic Review and Meta-analysis.
  16. Am J Clin Nutr. 2016 Dec;104(6):1534-1544. Whey protein lowers blood pressure and improves endothelial function and lipid biomarkers in adults with prehypertension and mild hypertension: results from the chronic Whey2Go randomized controlled trial.
  17. Journal of Nutrition & Intermediary Metabolism, Volume 2, Issues 3–4, December 2015, Pages 69-75. Beneficial effects of whey protein preloads on some cardiovascular diseases risk factors of overweight and obese men are stronger than soy protein preloads – A randomized clinical trial.
  18. Nutrition & Metabolism volume 10, Article number: 46 (2013). Milk protein for improved metabolic health: a review of the evidence.
  19. PeerJ. 2017; 5: e2825. Pre- versus post-exercise protein intake has similar effects on muscular adaptations.
  20. Journal of the International Society of Sports Nutrition volume 10, Article number: 53 (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis.
  21. Journal of the International Society of Sports Nutrition volume 9, Article number: 54 (2012). Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training.
  22. The American Journal of Clinical Nutrition, Volume 99, Issue 1, January 2014, Pages 86–95. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise.
  23. Physiol Rep. 2016 Aug; 4(15): e12893. The response of muscle protein synthesis following whole?body resistance exercise is greater following 40 g than 20 g of ingested whey protein.
  24. British Journal of Nutrition, Volume 108, Issue 1028 November 2012, pp. 1780-1788. Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men.
  25. Adv Nutr. 2018 May; 9(3): 171–182. Perspective: Protein Requirements and Optimal Intakes in Aging: Are We Ready to Recommend More Than the Recommended Daily Allowance?
  26. Br J Nutr. 2012 Sep 28;108(6):958-62. Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men.
  27. Front Pharmacol. 2019; 10: 317. Efficacy and Safety of Whey Protein Supplements on Vital Sign and Physical Performance Among Athletes: A Network Meta-Analysis.
  28. Am J Clin Dermatol. 2021; 22(1): 55–65. Effects of Diet on Acne and Its Response to Treatment.
  29. Toxicol Rep. 2020; 7: 1255–1262. A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements.
  30. Gropper SS, Smith JL, Carr TP. Advanced Nutrition and Human Metabolism. Eighth ed. Boston MA: Cengage Learning; 2022.
  31. Food Nutr Bull. 2018 Sep;39(2_suppl):S54-S59. Association of Dairy Protein Intake During Pregnancy with Birth Weight.
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Andreas Abelsson

Andreas is a certified nutrition coach with over three decades of training experience. He has followed and reported on the research fields of exercise, nutrition, and health for almost as long and is a specialist in metabolic health and nutrition coaching for athletes. Read more about Andreas and StrengthLog by clicking here.