Whey protein vs whey isolate: what's the difference?

Choosing between whey protein vs whey isolate? From the taste and the calories to the protein content and the price – here are all the differences

Man scooping whey protein powder
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What's the difference between whey protein vs whey isolate? If you already use one of the best protein powders for weight loss, you’ll know how beneficial using a nutritional supplement can be for hitting your health and fitness goals. And whey protein and whey isolate is another example of this, as they can keep you fuller for longer in between meals while increasing your all-important protein intake. 

But what supplement should you choose if you’re hoping to lean up? And what calorie intake does whey protein vs whey isolate have? Generally speaking, whey protein comes from cows milk and is the most common form of protein powder. While whey isolate also derives from dairy, as it’s a by-product of cheese. But unlike whey protein, whey isolate contains little or no lactose, which is a sugar found in milk. Due to this, it has a lower calorie content, a lower fat level and a higher protein intake per serving.

But these aren’t the only differences. We spoke to a dietitian to find out the production process, protein content and benefits of each.  

Expert input from
Theresa Gentile
Expert input from
Theresa Gentile

Theresa Gentile, MS, RDN, CDN, Brooklyn, N.Y., is a National Media Spokesperson for the Academy of Nutrition and Dietetics. She is the coordinator of the home enteral nutrition program at Maimonides Medical Center and owns a nutrition consulting practice where she focuses on cardiac health and weight management by improving women's metabolisms. She previously served as an adjunct faculty member at CUNY Brooklyn College and has earned the Distinguished Dietitian of the Year Award from the Greater New York Dietetic Association. Gentile earned undergraduate and master’s degrees from CUNY Brooklyn College. 

Whey protein vs whey isolate: production process 

On the surface, whey protein vs whey isolate sound and look very similar. But how are they made? And how does the production process differ?

Theresa Gentile, MS, RDN, CDN, National Spokesperson for the Academy of Nutrition and Dietetics says: “Whey is the liquid part of milk in the cheese-making process and is composed of the 8 proteins found in milk. In the process to make cheese, enzymes are added to milk that cause it to curdle, separating the liquid whey from the solid curds. The liquid part is the whey, which contains lactose and fat. Manufacturers pasteurize and dry the whey to form a powder.” 

But this is where they differ. Unlike whey protein, whey isolate undergoes more processing, as it has most — if not all — of its lactose content removed. And, before both supplements hit the shelves, most manufacturers add flavoring to the whey powder to make them more appealing to consume.  

Whey protein vs whey isolate: protein content 

Whether it’s to hit their macros, fuel recovery or increase strength, most people take whey protein or whey isolate because of the high protein content both supplements have. But how do they stack up against each other? 

According to Gentile: “Whey protein concentrate (sometimes called sweet whey) has a protein concentration of 70-80% and contains some lactose (milk sugar) and fat.”

“While whey protein isolate is the concentrate minus some of the carbohydrates and fat — it 'isolates' the protein portion, the whey. This results in a product whose protein concentration is about 90% and is absorbed faster than whey protein concentrate.”

Person making health protein shake in kitchen

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Whey protein vs whey isolate: pricing and availability  

Price-wise, whey isolate usually costs a little bit more than whey protein. You can pick up a tub of Optimum Nutrition Gold Standard 100% Whey Isolate Powder (opens in new tab) for $46.99. For this price you can enjoy 24 servings. While the brand’s same size tub (opens in new tab) for whey protein costs $37.99

Whey isolate is usually more expensive because it has to undergo more processing.  

In today’s on-demand world, you can pick up both of these forms of protein online or in most big grocery stores. Plus, you can find some great deals on these supplements especially around the Christmas period and new year. So do keep your eye on our deals page, where we scour the internet to find you the best price on health and fitness musts.  

Whey protein vs whey isolate: verdict

If you’re just after a drink to add more protein to your diet without additional calories, fat or triggering any digestive issues with lactose you may have, whey isolate is what you’re after. However, whey protein, as a more common supplement, is often seen on offer and at far greater varieties of flavour. If you’re just after a high-protein supplement solution to add to your diet, feel free to pick up either supplement without any further concerns.  

Woman making protein shake at home

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Whey protein vs whey isolate: What are the benefits? 

1. Whey can help you build muscle

Both whey protein and whey isolate come with a whole host of benefits. 

As Gentile explains: “Dietary whey supplementation before and after resistance exercise can increase protein synthesis. One placebo-controlled study found that ingesting whey protein before and after exercise resulted in more muscle strength and building.”

2. Whey can be absorbed fast

Whey’s absorption rate has been estimated at ~ 10g per hour. Research published in the Journal of the International Society of Sports Nutrition states it would take just two hours to fully absorb a 20-g dose of whey. While the same research states it would take around seven hours to complete absorption of an omelet containing the same 20g of protein. 

But what has a slower absorption rate? Whey protein or whey isolate?

“Whey protein,” Gentile says. “It’s because of its higher calorie and fat content, it is absorbed slower than the other forms of whey.”

3. Whey isolate can be taken by those who are lactose-intolerant 

Due to the additional manufacturing process whey isolate undergoes, it contains less (or in some cases no) lactose. This makes it a popular choice for those who are lactose intolerant. 

And while whey protein doesn’t have masses of lactose in it, it could cause ‘bloating/stomach issues for those who are sensitive to lactose’, Gentile warns. 

Decided on what’s the most suitable protein powder for you? Discover our guide to the best protein powder for women

Becks Shepherd

Becks is a freelance journalist and writer with more than 7 years of experience in the field. She writes health and lifestyle content for a range of titles including Live Science, Top Ten Reviews, Tom’s Guide, Stylist, The Independent, and more. She also ghostwrites for a number of Physiotherapists and Osteopaths. 


Health has been a big part of Becks’ lifestyle since time began. When she’s not writing about the topic of health, she’s in the gym learning new compound exercises. And when she’s not in the gym, she’s most probably reading. 

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