What is Whey Protein? Benefits, Side Effects, & Correct Dosage

Whey protein is the most common supplement for sports enthusiasts and bodybuilders. It is commonly associated with speed, strength, and growth of lean muscle mass. But do you know that is whey protein and how it benefits the body? Read on to find out.

What is whey protein?

Milk contains two categories of proteins  – casein and whey. Whey protein is the natural product of the cheese or the curd making process. You start with milk and strain out curds for cheese or yogurt, leaving the whey behind. After processing, whey protein is sold as a powder.


Whey protein is a complete protein as it contains all essential amino acids. It is rich in leucine and cysteine. Protein sources that provide leucine are the strongest determinant of muscle protein synthesis and growth. Whey protein is also low in lactose content.

Types of whey protein

There are three primary types of whey protein, depending on the way they have been processed –

1. Whey protein concentrate

Whey protein concentrate contains 70 to 80% protein. It has low levels of fat and carbohydrates. It also contains some lactose. It has the best flavor.

2. Whey protein isolate

It contains at least 90% protein. It contains very little to no fat or lactose. It lacks many beneficial nutrients found in whey protein concentrate.

3. Whey protein hydrolysate

Whey protein hydrolysate has already undergone hydrolysis. It is considered to be pre-digested, which means that it gets absorbed faster. It causes up to 43% greater spike in insulin levels as compared to isolate.

This form of whey protein is used in medical supplements and infant formulas because it is digested better, and it has reduced allergen potential. Whey protein concentrate is the most popular form of a supplement as it had the best taste. It also retains several of the beneficial nutrients found in whey. Whey protein isolate and hydrolysate may not taste as good, but they are easier to digest.

Benefits of whey protein

1. Boosts protein intake

Whey protein is a complete high-quality protein, which contains all essential amino acids. It is particularly rich in important branched-chain amino acids (BCAAs) like leucine, and also includes a high amount of cysteine. Studies show leucine is the most anabolic amino acid (growth-promoting), and cysteine can help boost levels of the cellular antioxidant glutathione.

Whey protein stimulates growth in humans. Human breast milk is 60% whey. Whey protein is also the most easily digestible form of protein. It also gets absorbed from the gut very quickly (1). These qualities make it one of the best sources of protein.

2. Increases muscle mass

Whey protein is best known for increasing muscle mass and strength. This is the reason why bodybuilders, athletes and fitness models use whey protein. Whey protein is a rich source of amino acids which are the building blocks for muscles. It also increases the release of anabolic hormones like insulin, which help stimulate muscle growth.

Whey is particularly rich in a branched-chain amino acid called leucine. Leucine stimulates muscle protein synthesis at the molecular and genetic levels (2). This is the reason why whey prevents age-related muscle loss (3). Whey protein has been especially useful in increased muscle growth when consumed right after resistance exercise (4).

3. Aids weight loss

It is a well-known fact that protein improves satiety and reduces food cravings. However, not all proteins have the same effect. Studies have shown that whey protein supplements have a stronger effect on satiety and reducing food cravings as compared to casein and carbohydrate supplements (5).  This property of whey makes it highly useful for weight loss.

According to a 2008 study, a whey-protein supplement increases fat loss and spares lean muscle in obese people (6). Another study showed that when participants replaced whey protein with other sources of calories and included resistance training in their daily schedule, they lost around eight pounds and increased lean muscle mass (7).

4. Helps lower blood pressure

High blood pressure can increase the risk factor for heart disease. Several studies over the years have shown that consuming milk products can lower heart disease (8, 9). Milk products contain angiotensin-converting enzyme inhibitory peptides, which exhibit significant antihypertensive effects (10). Whey protein also contains ACE-inhibitors called lactokinins. Several studies have shown that they have a beneficial impact on high blood pressure (11).

According to a 2010 study, when patients with hypertension took 28 grams of a whey protein beverage, it significantly reduces their blood pressure (12).

5. Helps in diabetes treatment

According to new research, whey protein can help control blood glucose levels in people with type-2 diabetes, when eaten before breakfast. Researchers from Newcastle University discovered the beneficial effect of whey protein for diabetes through two small studies. During one study, when 12 obese men ate 20 grams of whey before a high-calorie breakfast and walked for 30 minutes, they achieved better blood sugar levels.

During another study, 11 men with type 2 diabetes were given 15 grams of whey protein before breakfast. They achieved similar improvements. A study from the University Hospital MAS, Sweden, the addition of whey to meals stimulates insulin release and reduces postprandial blood glucose excursion in type 2 diabetic subjects (13).

6. May improve asthma in children

Whey protein can also modulate the immune response in children with atopic asthma. According to a study by the Department of Respiratory Medicine, Montreal Children’s Hospital, children with asthma who were supplemented with 10 grams whey protein twice a day for one month, had an improved immune response (14).

7. Can reduce inflammation

Lactoferrin, a minor protein found in whey protein, has been researched for its anti-inflammatory effects. Studies show that it boosts immunity and also suppresses immune response to block inflammatory diseases.

According to a 2015 study, whey protein supplementation is beneficial for human health, possibly by reducing the circulating C-reactive protein (CRP) level, a sensitive marker of inflammation (15).

8. Lowers IBS symptoms

Inflammatory Bowel Disease is characterized by the chronic inflammation of the intestinal lining. Glycomacropeptide, a protein found in whey, can reduce intestinal inflammation. During one study, when rats with colitis were given milk-casein derived glycomacropeptide, it had an anti-inflammatory effect. This anti-inflammatory effect was comparable to that of sulfasalazine, a drug used in the treatment of IBS (16).

During another study, when patients with Crohn’s disease were given glutamine or whey protein, their intestinal permeability and morphology improved significantly (17).

9. Reduces cholesterol

Research shows that whey protein helps to lower cholesterol levels and reduce the levels of triglycerides. According to an article in the British Journal of Medicine, when 70 overweight men and women took whey supplements for 12 weeks, they showed a significant decrease in total cholesterol and LDL (18).

10. Protects against cancer

Whey protein may protect against cancer. According to a 2003 study from the Ohio State University, when scientists treated human prostate cells with whey protein, cellular levels of the antioxidant glutathione increased. Antioxidants like glutathione help to control cancer-causing free radicals (19).

Whey protein also helps to reduce cancer colon risk. According to a 2001 study, whey protein, when rats with chemically induced colon cancer were given whey protein, it reduced the risk of developing colon tumors (20).

Side effects of whey protein

When taken in moderate doses, whey protein does not cause any problems. Consuming very high doses of whey can lead to problems like stomach pains, cramps, bloating, reduced appetite, nausea, headache, and fatigue. You must also remember that taking too much whey protein is useless. Our body can only utilize a small amount of protein at a time.

People who are lactose intolerant may also be allergic to whey. Whey protein isolate or hydrolysate may be more suitable for such people. People with liver or kidney problems should consult with their doctor before taking whey supplements. High doses of whey protein can also cause acne in some people.


Recommended dosage

The commonly recommended dosage of whey protein is one or two scoops (25 to 50 grams) per day. You should take whey protein after your workout. A two-scoop serving of whey provides 30 grams of protein and only 170 calories. It also contains just 8 grams of carbohydrates.

Final thoughts

Whey protein is considered a complete protein as it contains all essential amino acids. Athletes and bodybuilders commonly use whey protein along with resistance exercise to improve lean muscle mass and strength.  Other benefits of whey protein include weight loss, lower blood pressure, and cholesterol levels. Whey protein also helps in lowering the risk of cancer, reducing intestinal inflammation, diabetes management, and treatment of asthma in children.

Experts generally recommend that you take one or two scoops of whey protein a day. Whey protein does not cause any side effects when taken in moderation. High doses of whey can lead to stomach pains, cramps, bloating, reduced appetite, nausea, headache, and fatigue. People with liver or kidney problems should avoid taking whey protein.


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