Two tablespoons of peanut butter. Three-quarters of a cup of unsweetened almond milk. One half-cup of oats. And the most important ingredient: chocolate-flavored whey protein. Blended together, this has been my typical breakfast for a long time. Whey protein has been a part of my diet since my undergraduate days and has always been a convenient and affordable way to get some extra protein.

Whey protein supplementation is a common recommendation from every gym bro you know, but is there any evidence that shows it has actual health benefits?

Have I been wasting all my money over the years buying five-pound tubs of protein that cost 50 dollars? What does the science say?

What is Whey Protein?

Whey is a component of milk that is produced as a byproduct when making cheese. Because whey is very high in protein, it is typically isolated and marketed as a dietary supplement with many proposed benefits based on a few of its characteristics.

First, it is a complete protein, meaning it has all nine essential amino acids (building blocks of protein) that our bodies cannot produce.

Second, it has been shown to make you feel full which may, in turn, keep cravings at bay. Third, it is very quickly digested and rapidly brings amino acids into the bloodstream, which can jump-start muscle protein synthesis. Lastly, whey is high in leucine, an amino acid that plays a critical role in muscle protein synthesis (26).

Whey protein is ubiquitous; it can be bought in any grocery store, major retailer, or online, and comes in any flavor you can think of. It typically comes in one of three forms; concentrate, where there is still some fats and carbohydrates with it, isolate, where it is mainly protein without any leftovers, and hydrolysate, where the protein is partially broken down into amino acids.

Typically, a serving of whey protein contains 20-30 grams of protein, a few grams of fat and carbohydrates each, and is fortified with vitamins and minerals. Protein supplements are extremely common in weightlifting, powerlifting, and bodybuilding communities, but are marketed to almost everyone.

Is There any Research?

Whey protein has been the subject of many research articles. A preliminary search on PubMed, a popular website indexing healthcare research, reveals 1,194 articles with “whey protein” in the title. Much of the research has focused on the effects of whey protein on muscle strength, weight loss, satiety levels, diabetes, cardiovascular disease, and overall health. There is a significant number of studies to dig into here.

Does Whey Protein Increase Strength and Build Muscle?

Whey protein is most commonly used as a supplement to improve strength and build muscle. It is also recommended for older adults when muscle loss, termed sarcopenia, becomes more common. What does the evidence say?

The current evidence supports whey protein as part of a healthy diet that can result in small improvements in strength and muscular size, although the literature is somewhat mixed. One large review of 49 studies looked at protein supplementation of all kinds.

Half of the studies used whey and found that it was associated with enhanced muscle strength and size. However, they found that there was no additional benefit going beyond 1.6 grams of protein per kilogram of body weight each day (28).

The International Society Of Sports Nutrition’s most recent position on whey protein echoes this sentiment and suggests that protein supplementation can help increase muscle protein synthesis when combined with exercise. The appropriate intake for this goal is around 1.4 to 2.0 grams of protein per kilogram of body weight (20).

In addition, a review of 22 studies from 2012 found that protein supplementation of all types can help to improve the response to resistance training, supporting increases in muscle mass and strength (5). In a review of nine studies from 2015, the authors found that whey protein supplementation seems to increase fat-free mass, as well as facilitate increases in muscular strength better than carbohydrates or other sources of protein (29).

However, a pair of trials from 2016 and 2017 found that whey protein supplementation only provided small improvements in lean mass and no real changes in strength (31, 32). The authors conclude, “We propose that as long as protein intake is adequate during muscle overload the adaptations in muscle growth and function will not be influenced by protein supplementation.”

For older adults, protein supplementation, in combination with a healthy diet and exercise, can help prevent age-related muscle loss (37). Two strong placebo-controlled trials from 2015 and 2016 showed that whey supplementation can help induce positive changes in fat-free mass and strength, although the differences were relatively small (3, 33).

However, a review from 2017 found that whey protein supplementation did not find any significant improvements in muscular strength or muscle mass in the elderly (9).

Bottom Line

Whey protein can be part of a healthy diet to support increasing strength and building muscle for people of all ages, but broader trends like consistent workouts and overall dietary patterns are probably more responsible for the majority of the changes one would see. The research is mixed with regards to optimal dosage, timing, and effect size.

Does it Help Burn Fat?

Whey protein supplementation has been proposed as a way to help lose weight, and has been the subject of many research projects. Much of the current research thus far suggests that whey protein ingestion has modest but real effects on overall body composition.

A 2018 review of 13 studies suggested that in women, whey protein can help increase lean mass (muscle), without significant lowering of fat mass or total mass, although the effect was very small. The authors concluded that the perception that protein supplementation will make women appear bulky is not supported. In addition, they suggested that the energy restriction, i.e. eating fewer calories, was the most influential factor when looking at fat mass changes (4).

Another review of 14 studies came to a similar conclusion and found that using whey protein as a supplement or to replace a meal results in positive changes to body weight and body fat percentage. However, again, the results were small, and the results were more pronounced when combined with a weight loss diet and/or a resistance training program (26).

Two small trials showed that utilizing whey protein supplementation while dieting can help with preserving muscle mass and burning more fat (10, 14). However, another larger study of 151 people found that whey supplementation after a period of weight loss did not help people any more than just consuming the recommended amount of protein (21).

Bottom Line

Whey protein may be a part of a healthy diet that can help you lose weight, but science suggests the effects are small. Broader trends, such as your overall dietary patterns and physical activity levels, have a bigger role.

Does it Reduce Cravings?

Protein is anecdotally known to make you feel fuller compared to other nutrients. Therefore, many have speculated that whey protein supplementation may help to reduce cravings, make you feel more full, and thus reduces how much food you eat. A review of eight studies found that it may, in fact, reduce appetite in the short-term and long-term, but it probably doesn’t do it any better than carbohydrates in the short term (27).

Bottom Line

Whey protein may make you feel fuller and help you not eat as much, but comparisons to other types of food are either not present or equivocal.

Does it Stabilize Blood Sugar Levels?

The effects of whey protein ingestion on blood sugar levels have been the subject of many research articles and have led researchers to suggest whey protein as a way to help manage type 2 diabetes. Is there any merit to this?

One study had 56 people with diabetes put on a diet, but they were randomized to have one of three possible breakfasts; one mainly with whey protein, one with protein from different sources, and one with mainly carbohydrates. After 12 weeks, the researchers found that all groups had beneficial changes, but the whey protein breakfast was the best at reducing fasting glucose, the glucose spike after breakfast, and HbA1C, a measure of glucose levels over time (18).

However, a similar 12-week study failed to show any advantages of whey protein over casein protein or a carbohydrate control supplement in regards to fasting blood sugar (30).  In addition, a placebo-controlled trial looked at the effects of whey protein supplements combined with mixed exercise in patients with diabetes and failed to find any significant benefits with glucose control over the placebo (15).

A few short-term, small-scale studies have also shown that ingesting whey protein prior to a heavy meal can reduce blood sugar spikes and improve the response of insulin (8, 19, 22). One study found that whey protein was able to reduce blood sugar spikes compared to a placebo, but the magnitude of the effect depended on multiple factors, including the subject’s BMI and triglyceride levels. Whey protein had bigger effects on patients that were healthier (2).

According to one review, whey protein may help to slow gastric emptying, meaning it slows down how quickly the food you eat goes from your stomach to your intestines. This, along with a few other effects, may help to decrease spikes in glucose. While the current evidence suggests whey protein may have a role in diabetes management, we need more long-term studies (25).

Bottom Line

Incorporating whey protein in your diet, among other important dietary changes, may help manage blood sugar and thus may be beneficial for diabetics. However, we need longer-term studies, and some studies show conflicting results.

Does it Improve Energy?

Can whey protein supplementation improve your energy? This claim can become messy because it depends on what you mean by energy. If by energy you mean feeling alert or energetic, you should probably just stick to coffee. I was unable to find any studies that tested the effects of whey protein on alertness.

If you’re asking if it increases the amount of energy, also known as calories, that you take in, then yes it does. However, so does every other food with calories. And typically, protein is not used for energy in your body as it has other important jobs to do.

If you’re asking if whey protein can improve performance on different physical tasks like running or lifting weights, that is a slightly different question. But again, the claim is difficult to investigate because of loose definitions, broad statements and other factors that might not be taken into account. There are certainly both human and animal studies that suggest whey protein has beneficial effects on performance (6, 17, 34, 35), but the science is still trickling in.

Bottom Line

It is difficult to design an appropriate study to determine if whey protein improves energy levels because of overly broad and imprecise claims. I have not seen a study that adequately addresses this, but it is still an open question.

Does it Boost Glutathione?

Glutathione is an antioxidant with multiple functions that all humans produce and can be found in certain foods. In addition, it is often taken directly as a supplement to help deal with various health problems. The production of glutathione requires the amino acid cysteine, which is produced by the body but is found in all complete proteins, whey included. Many have speculated that whey protein supplementation may help to increase glutathione production.

Multiple small trials have shown that whey supplementation can help increase glutathione in healthy subjects (38) as well as patients with strokes (1), liver disease (7), cystic fibrosis (16), and HIV (23, 24). The quality of these trials varied, but they were all small and only some were blinded.

Bottom Line

Whey supplementation may help to improve glutathione levels in various groups of patients but it is unclear if this translates into real health benefits.

Does it Improve Heart Health?

According to one review of nine randomized controlled trials, whey protein was shown to be associated with small improvements in blood pressure, total cholesterol, fasting blood sugar, and lean body mass (36). While this study falls short of concluding people who supplement their diet with whey protein are less likely to get heart disease, improvements in these risk factors hint at a mediating relationship.

The same researchers did a pair of small studies from 2016 and 2018 on people with slightly elevated blood pressure. They found that whey protein intake was associated with decreases in blood pressure and it outperformed carbohydrate solutions acting as a placebo. (11, 12). Another trial from 2010 done over 12 weeks found that whey protein supplementation helped to reduce blood pressure for people whose blood pressure was already elevated (13).

However, a review from 2016 looking specifically at changes in blood cholesterol came to a negative conclusion. They found that in 13 studies, seven of which were double-blinded, there were essentially no changes in cholesterol levels (39).

A review and analysis of nine trials were performed in order to assess the effects of whey protein on C reactive protein, an indicator of inflammation associated with cardiovascular disease, as well as other chronic diseases. They found the current evidence was not sufficient to show whey protein had any beneficial effects on CRP (40).

I was unable to find any long-term studies looking at whey protein and its association with actual cardiovascular diagnoses like heart attacks, strokes, arterial disease or anything else.

Bottom Line

Whey protein may help to improve markers of cardiovascular health, but the effects are small, some of the research is mixed, and there are no long-term studies. Overall dietary trends, physical activity levels, and genetics probably influence these things more than whey protein consumption.

Does t Extend Life Span?

In order to truly answer this question, here is the study you would need to perform: have one group of people supplement their diet with whey protein and one group of people utilize a placebo, and see which group, on average, lives longer. As far as I am aware, this study has not been performed. There are animal studies that have looked at life spans, but none in humans.

And even if the aforementioned study would come out, it would have to be very carefully undertaken because there are many confounding variables that could influence the results, including dietary patterns, health conditions, non-health related deaths, and many others.

Bottom Line

While whey protein may help support a healthy diet, and thus induce positive changes in someone’s overall health, we have no direct evidence to suggest whey supplementation can help you live longer.

Is Whey Protein Safe?

Whey protein is generally regarded as safe anecdotally, but there are not many studies that have investigated this directly.

The majority of studies I came across did not assess safety risks at all, but the few that did reported whey supplementation was well-tolerated (3, 8, 9, 33). However, some studies did have a small percentage of subjects report gastrointestinal discomfort (7, 13, 23, 24). Lastly, if you cannot tolerate dairy products, whey protein should be avoided.


The science on whey protein is mixed. It has many interesting and beneficial effects, and can be a small component of a healthy diet and exercise program designed to build muscle, lose weight, or manage certain conditions. However, the research clearly shows the effects of whey protein itself are generally small, and other factors have a bigger influence on your health. Whey protein is not a magic bullet that will help you achieve your health goals, but merely a convenient way to add a healthy component to your diet.

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