Whey Protein Isolate vs Hydrolyzed: An Expert Guide (2024)

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These days, it feels like everyone in the health and nutrition space is preaching to eat more protein, and for good reason. The benefits of increasing protein intake range from building lean muscle to enhancing mealtime satiety, aiding fat loss, and supporting healthy aging.

Protein powder is one of the easiest ways to help you boost protein intake. Whey protein is considered at the top of the leaderboard among the other types of protein powders, but did you know there are three types of whey protein?

Whey concentrate is the most common form of whey protein, but there’s also whey protein isolate and hydrolyzed whey protein. If the words isolate and hydrolyzed are making you wonder if you need a science degree to decode protein powders, I’m here to help.

RELATED: Best Protein Powder

As a registered dietitian, I’m sharing my sports nutrition knowledge and breaking down whey protein isolate vs hydrolyzed whey. Read on for more on the production of each type, their nutritional profiles, and how to decide which is best for your needs and goals.

Medical disclaimer: This article is intended for educational and informational purposes only. It is not intended as a substitute for medical advice. For health advice, contact a licensed healthcare provider.

First Things First: What is Whey Protein?

Before we dive into the nitty gritty of whey protein isolate vs hydrolyzed whey, let’s review what whey protein is and where it comes from.

There are two proteins found in dairy milk: whey and casein. During cheesemaking, a type of enzyme, called rennet, is added to milk. This enzyme causes the casein protein to clump together and form curds, which will eventually be made into cheese. The curds separate from the whey, which is the remaining liquid portion.

The liquid whey is strained and then heated to evaporate the water content. What’s left behind is dehydrated whey protein, which is used to make gold standard whey protein powder. The dried whey then undergoes additional processing to make one of three different types of whey protein:

Whey protein concentrate
Whey protein isolate
Hydrolyzed whey protein, also known as whey hydrolysate or predigested whey

These whey proteins differ in their manufacturing process and nutrition content.

Production of Whey Isolate vs Hydrolyzed Whey Proteins

Whey concentrate is filtered to remove some fat and carbs, thereby “concentrating” the protein content. Whey isolate goes through an extra filtration process to remove even more fat and carbs.

Hydrolyzed whey is most commonly made from whey isolate. The isolate undergoes the scientific process of hydrolysis, which is treatment with heat, acid, or enzymes to break down the bonds holding proteins together.

Think of it this way: hydrolysis is like digestion. It breaks the proteins down into smaller pieces, called peptides, that can be digested easier due to their faster absorption rate.

Registered dietitian Chelsea Rae Bourgeois previously discussed whey protein concentrate vs whey protein isolate, but for now, I’ll focus on the similarities and differences between whey protein isolate and hydrolyzed whey.

Key Similarities Between Whey Isolate and Hydrolyzed Whey Proteins

Let me continue the comparison by breaking down what these two protein forms have in common.

Macronutrient Content

Both forms of whey contain similar amounts of carbs, fat, and protein. It’s common to see hydrolyzed whey described as having all of the carbohydrates and fat removed, essentially leaving behind pure protein. That’s not exactly the deal.

Hydrolysis only acts on proteins, so unless a hydrolyzed whey is additionally processed to remove more macronutrients, it will contain the same amount of carbs, fat, and lactose as the isolate it was made from.

Some isolates and hydrolyzed whey products contain zero fat or carbs, while others may list 1 to 2 grams per serving. Even if it’s only a couple of grams, the macronutrient content may be an important factor if you’re trying to lose or gain body weight or are following strict macro ratios, like on a keto diet, so be sure to read the label.

RELATED: What is the Keto Diet?

Lactose Content

The extra filtration that removes carbohydrates from these proteins also removes the majority of lactose. Lactose is a naturally occurring sugar (aka carbs) found in dairy milk.

People with lactose intolerance have a hard time digesting lactose, resulting in digestive issues like bloating, gas, and diarrhea. Although whey isolate and hydrolyzed whey contain very small amounts of lactose, they’re considered easier to digest for folks with extreme lactose sensitivity.

High Protein by Weight

Both whey isolate and hydrolyzed whey contain more protein by weight than whey concentrate. Whey isolate contains at least 90% protein by weight compared to concentrate, which can range from 50% to 80% protein content.

The reason for this is the extra filtration whey isolate and hydrolyzed whey go through. Removing most of the fat and carbs from whey isolate concentrates the protein content. Hydrolyzed whey has the same protein content because it’s made from isolate.

A serving of whey isolate or hydrolyzed whey will contain more protein than a same-size scoop of concentrate.

Complete Protein

All types of whey protein are complete proteins, meaning they contain all nine essential amino acids. Complete proteins are considered high-quality proteins.

If you need a refresher, essential amino acids are the ones our bodies can’t make on their own and need to come from food. You need essential amino acids for normal maintenance and repair of tissues, so you can imagine how important they are for increasing muscle strength and size.

Contains BCAAs

Because whey isolate and hydrolyzed whey are complete proteins, they’re natural sources of branched-chain amino acids (BCAAs). Although research-based evidence is mixed, BCAAs are considered some of the most important amino acids for muscle health and exercise performance. Leucine¹, in particular, has been linked to enhanced muscle protein synthesis, improved workout recovery, and more muscular endurance during exercise.

Bioavailability

The amino acids in all forms of whey protein are considered highly bioavailable². Bioavailability simply refers to how much of a substance—in this case, protein—your body can absorb and put to use. Whey isolate and hydrolyzed whey are highly absorbable proteins.

Marketing wants you to believe that products labeled 100% hydrolyzed whey are more bioavailable than any other whey form, which isn’t accurate.

Hydrolyzed protein tastes bitter, so the higher the percentage of hydrolyzed protein, the worse the end product will taste. Most importantly, studies³ have found the more hydrolyzed whey is, the less bioavailable it becomes.

So, products claiming 100% hydrolyzed whey as the sole protein source will have the same bioavailability as 100% whey isolate.

Key Differences Between Whey Isolate and Hydrolyzed Whey Proteins

Now, for the differences:

Allergenicity

The proteins in milk trigger an immune response in people with diagnosed milk allergies. Studies have found that hydrolyzed proteins⁴, like hydrolyzed whey, are less likely to trigger allergic reactions in people with milk protein allergies.

Some people with a milk allergy may be able to tolerate hydrolyzed whey, not whey isolate. Hydrolyzed whey is still a product made from milk, though, so you should check with a doctor before trying it if you have a milk allergy.

Digestion Speed

The intention of hydrolyzed whey is to be digested and absorbed faster than other types of whey protein. It makes sense: the proteins have been broken down to some extent, so your body has to do less work to digest them.

Whey protein is already a fast-acting protein⁵, so the edge hydrolyzed may provide is minimal. More research is needed to compare the digestion rate of hydrolyzed whey vs whey isolate. The existing studies have found that hydrolyzed whey is digested slightly faster or at about the same rate as whey isolate.

Side-By-Side Comparison

Here, we compare a 20-gram serving of whey isolate vs a 20-gram serving of hydrolyzed whey.

	Whey Isolate	Hydrolyzed Whey
Calories	72	73
Protein	17 g	15 g
Carbs	1 g	2 g
Fat	0 g	1 g
Fiber	0 g	0 g
Iron	0 mg	0 mg
Calcium	80 mg	80 mg

Which Is Better For ….

Let’s take a look at how these two proteins can benefit the following fitness goals.

Muscle Building and Muscle Gain

Studies have found both types of whey⁶ may help you gain muscle and increase muscle strength when paired with resistance training⁷. Most of the research studying the effect of whey protein on muscle protein synthesis uses whey protein isolate as the variable, so it’s a great choice if you want the most researched-backed form of protein.

Weight Loss

A 2019 meta-analysis⁸ found all forms of whey may help support weight loss. Isolate and hydrolyzed are better choices than concentrate for weight loss because they contain fewer calories, fat, and carbs per serving.

Recovery

Studies have found all forms of whey may speed up recovery⁹, whether taken before or after a workout. However, hydrolyzed whey may be the better choice to support post-workout recovery if you subscribe to the theory of timed nutrition.

There’s some debate on the concept of when you refuel after exercise. The thirty minutes immediately following your workout is often called the anabolic window. The idea is that when your muscles are depleted from exercise, your body will more efficiently use whatever nutrition you provide during that window.

On the other hand, many fitness and nutrition professionals say the overall quality of your diet and the total amount of protein you eat daily are more important.

Who Should Use Whey Protein Isolate?

Whey protein isolate is ideal for anyone who wants to add more protein to their daily total. Products made with whey protein isolate tend to contain more protein per serving than products containing whey concentrate. Those extra grams of protein can be important for bodybuilders, athletes, and anyone trying to grow muscle.

Isolate is also a good choice for anyone who wants to increase protein intake while keeping carbs and fat low, such as calorie-controlled diets for weight loss and low-carb or ketogenic diets. Be sure to read the ingredients and the supplement facts to check the calories and macronutrient amounts for a serving of protein.

Whey protein isolate may be worth trying if you have mild lactose intolerance or have had trouble digesting whey protein concentrate since it contains less lactose than whey concentrate and may be tolerated better. Read the ingredients before buying since many whey isolate products occasionally contain whey concentrate.

RELATED: What Is Protein Isolate?

Who Should Use Hydrolyzed Whey?

Hydrolyzed whey offers the same benefits as whey isolate, with a few differences.

As mentioned above, the efficacy of post-workout nutrition timing is up for debate. Still, many gym-goers swear by downing a protein shake immediately after exercising. The extra-fast digestibility rate of hydrolyzed whey may appeal to athletes who want every advantage they can get.

RELATED: Best Protein Shakes

Because the hydrolyzed protein is predigested, it may be a better choice for individuals with food sensitivities, allergies, or other digestive issues, like irritable bowel syndrome or following gastric surgery.

Of course, individuals with medical concerns should speak with a doctor before experimenting with any protein powder.

Whey Protein Isolate vs Hydrolyzed: FAQs

Which is better: whey protein isolate or hydrolyzed?

Both whey protein isolate and hydrolyzed whey can help you consume more protein and support muscle growth and recovery. Isolate tends to cost less and taste better, but hydrolyzed whey may be digested and absorbed slightly faster, which appeals to those who practice timed post-workout nutrition. Ultimately, the choice comes down to individual preferences and budget.

Is hydrolyzed whey protein worth it?

Hydrolyzed whey is designed to be lean and fast/easy to digest, which may sound like an advantage if your goal is to build muscle and lose fat. There’s no scientific evidence that hydrolyzed whey benefits muscle gains or body composition more than other types of whey protein, so the cost isn’t justified unless you have trouble digesting the concentrate and isolate forms.

What is the highest quality whey protein?

In general, whey protein powders made with grass-fed whey, free from artificial flavors and sweeteners, and third-party tested are considered high quality. Whey isolate is considered the purest form of whey protein. It undergoes extra filtration to remove most of the fat, carbohydrate, and lactose content, which concentrates the protein content.

Is isolate really worth it?

Whey isolate costs more than whey concentrate and offers more protein per serving with fewer calories, fat, and carbs. Protein powders with 100% isolate are worth it if you’re looking for more protein per serving, eating a calorie-controlled diet, following a low-carb diet, or having a hard time digesting whey concentrate.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any diseases.

References

Vliet SV, Beals JW, Martinez IG, Skinner SK, Burd NA. Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food Consumption. Nutrients. 2018 Feb 16;10(2):224. doi: 10.3390/nu10020224. PMID: 29462924; PMCID: PMC5852800.
Phillips, S.M. The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutr Metab (Lond) 13, 64 (2016). https://doi.org/10.1186/s12986-016-0124-8
Farup J, Rahbek SK, Storm AC, et al. Effect of degree of hydrolysis of whey protein on in vivo plasma amino acid appearance in humans. Springerplus. 2016;5:382. Published 2016 Mar 31. doi:10.1186/s40064-016-1995-x
Salvatore S, Vandenplas Y. Hydrolyzed Proteins in Allergy. Nestle Nutr Inst Workshop Ser. 2016;86:11-27. doi:10.1159/000442699
Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10. Published 2018 Feb 27. doi:10.1186/s12970-018-0215-1
Moro T, Brightwell CR, Velarde B, et al. Whey Protein Hydrolysate Increases Amino Acid Uptake, mTORC1 Signaling, and Protein Synthesis in Skeletal Muscle of Healthy Young Men in a Randomized Crossover Trial. J Nutr. 2019;149(7):1149-1158. doi:10.1093/jn/nxz053
Lockwood CM, Roberts MD, Dalbo VJ, et al. Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males. J Am Coll Nutr. 2017;36(1):16-27. doi:10.1080/07315724.2016.1140094
A Castro LH, S de Araújo FH, M Olimpio MY, et al. Comparative Meta-Analysis of the Effect of Concentrated, Hydrolyzed, and Isolated Whey Protein Supplementation on Body Composition of Physical Activity Practitioners. Nutrients. 2019;11(9):2047. Published 2019 Sep 2. doi:10.3390/nu11092047
West DWD, Abou Sawan S, Mazzulla M, Williamson E, Moore DR. Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Performance Recovery after Resistance Exercise: A Double-Blind Crossover Study. Nutrients. 2017;9(7):735. Published 2017 Jul 11. doi:10.3390/nu9070735

Sharon Lehman, RD

Sharon Lehman, RD is a dietitian and health and nutrition writer. She earned a Bachelors degree in Dietetics from the University of Delaware and holistic health coach certification through the Institute for Integrative Nutrition. She has over 10 years experience as a dietitian and 5 years experience authoring evidence-based wellness content for various publications. She also specializes in culinary nutrition, recipe development, and food photography. You can view more of her work on her blog, Heart and Stove. (heartandstove.com)

Whey Protein Isolate Vs Hydrolyzed: “Wheying” the Pros and Cons of Each