Isopure Review: Best Keto Protein Brand?

Isopure Review: Best Keto Protein Brand?

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Isopure is a protein brand that's marketed as keto-friendly, and which is manufactured by a company called Glanbia Performance Nutrition. The company describes their protein powder line as "Pure & Simple," and offers low-carb and zero-carb options.

But do Isopure protein powders provide an effective protein dose for muscle building? Does the brand use any questionable additive ingredients? Is regular whey protein zero-carb? And how do real Isopure customers rate and describe the effects of this product line?

In this article we'll answer all of these questions and more, as we analyze the ingredients in two of Isopure's most popular protein powders based on clinical studies, to give our take on whether or not they're likely to be effective for muscle building, and whether or not they're healthy.

We'll review Isopure Protein Drink and Isopure Zero Carb Protein Powder.

We'll also feature unsponsored customer reviews, discuss whether regular whey protein contains carbs, and provide a cost comparison to show which retailers sell Isopure for the best prices.

Ingredient Analysis — Protein Drink

Isopure Protein Drink Grape Frost ingredients

The ingredients in the Grape Frost flavor of Isopure Protein Drink are shown above.

Whey protein isolate is the active ingredient, and this drink provides 32 grams (g) of protein per bottle, which should be maximally effective for muscle building.

A 2018 medical review suggests that around 25 g of protein post-workout or more provides maximal benefit for hypertrophy.

There are a number of inactive ingredients in this formulation that we consider to be unhealthy.

Phosphoric acid is clinically shown to be associated with low blood calcium levels.

Natural and artificial flavor are categorical descriptors that fail to identify the specific flavoring chemicals.

We consider artificial flavor to be particularly unhealthy, as some artificial flavors were shown to be toxic to animal cells in a clinical trial published in the Brazilian Journal of Biology.

Sucralose is an artificial sweetener shown to cause negative changes to insulin function in healthy, young adults, as we documented in our review of another protein brand called Seeq.

Red 40 and Blue 1 are artificial food dyes, and a 2020 meta-study on artificial food dyes and health stated the following:

"Artificial dyes have neurotoxic chemicals that aggravate mental health problems."

Overall, we consider Isopure Protein Drink likely to be effective for supporting muscle growth, but we don't currently recommend this product from a health perspective due to the inactive ingredients discussed above.

Before analyzing the ingredients in Isopure Zero Carb Protein Powder, we'll feature some unsponsored customer reviews of the brand.

Real People Try Isopure

A TikTok creator named Karla shares her experience using Isopure's protein powder:

@karlagonzalezxo An honest and chaotic review on Isopure infusions protein powder #isopureinfusion #isopureinfusions #isopureinfusionsmixedberry ♬ Chill Vibes - Tollan Kim

A TikTok creator named Eric Marinez shared his thoughts on the taste of Isopure Protein Drink:

@eric_marinez 🍹#isopureprotein #protein #foryou #share ♬ original sound - Eric Marinez

Ingredient Analysis — Zero Carb Protein Powder

Isopure Zero Carb Protein Powder ingredients

The ingredients in Isopure Zero Carb Protein Powder are shown above.

This product has a much simpler and "cleaner" formulation than the brand's Protein Drink, which is why we recommended Isopure Zero Carb Protein Powder as our top keto protein powder in our cleanest protein powder review article.

This protein powder provides 25 g of protein per serving, which we established in the previous Ingredient Analysis section to be an effective dose for muscle building.

Soy lecithin is an emulsifier that should be safe and non-toxic.

We generally prefer recommending protein powders sourced from pastured animals, but this matters less from a nutritional perspective with protein isolate than with full-fat products like dairy.

Overall, we consider Isopure Zero Carb Protein Powder likely to support muscle growth, and we consider this to be a healthy formulation.

Between the two products, we would definitely recommend this one over the Protein Drink.

Isn't Most Whey Low-Carb?

Isopure's marketing centers on its low-carb and zero-carb options, which is a somewhat strange value proposition in our opinion, given that whey protein isolate has low or zero carbs in most supplements.

Consider the Nutrition Facts label below from Nutricost Whey Protein Isolate:

Nutricost Whey Protein Isolate Nutrition Facts

This supplement contains only 1 g of carbs per serving, but also provides more protein and calories per serving.

For individuals on a ketogenic (keto) diet, perhaps it's worth paying extra for Isopure to save that 1 g of carbs per serving, but it's a substantial price premium.

Isopure Zero Carb Protein Powder currently costs $79.99 for 47 servings, or $1.70 per serving.

Nutricost Whey Protein Isolate currently costs $69.95 for 65 servings, or $1.08 per serving.

Since whey protein isolate should be functionally equivalent between brands, budget-conscious consumers may want to consider other whey protein isolate brands than Isopure.

Real Customers Review Isopure

Amazon is a better resource for honest customer reviews than a brand's website in our opinion.

Isopure Zero Carb Protein Powder has been reviewed over 44,000 times at the time of publishing this article, with an average review rating of 4.5 out of 5 stars.

The top positive review from a verified purchaser comes from a user named "AnnieK" who gives the product a 5/5 star rating, and who likes the taste:

"This is my go-to protein powder. No protein powder tastes good, including this one, but this one tastes better than all other protein powders. I would almost willingly drink this if I weren't using it for protein."

The top negative review from a verified purchaser is written by a user named "The Nagars" who gives the product a 1/5 star rating, and who claims it caused side effects:

"Neither my wife nor I have any allergies or any sensitivities to food. We both had intense abdominal pain and explosive diarrhea every time we drank this. The funny thing is that we honestly didn’t realize that the culprit was this protein shake we were sharing until I got really sick."

Isopure Zero Carb Protein Powder currently has an average review rating of 4.4 out of 5 stars on Google.

Our Clean Protein Picks

Bulletproof Collagen Protein is our top overall protein powder pick, because it only contains one single ingredient: collagen protein sourced from grass-fed animals.

As the core structural protein in skin, supplemental collagen is clinically shown to reduce visible signs of skin aging like wrinkles, which is a secondary benefit not found in other protein types.

Promix Whey Protein is our top whey protein powder, because it's sourced from grass-fed animals. 

Whey protein is a "complete" protein, meaning it contains all nine essential amino acids.

Complement Organic Protein is our top vegan protein powder.

The only ingredients in this protein powder are a blend of nutritious plant proteins: organic yellow pea protein, organic pumpkin seed protein, organic almond protein, organic sunflower seed protein and organic chia seed protein.

All of the products recommended in this section are entirely free of additive ingredients that we consider to be unhealthy.

Where to Get the Best Price

Isopure products are sold at a variety of online retailers. 

Here's a price breakdown for a one-time purchase of the two products reviewed in this article, at the time of publishing:

Isopure Protein Drink (12-pack)

Brand website: $59.99 (plus shipping, link)

Vitamin Shoppe: $54.99 (free shipping, link)

Amazon: $54.99 (free shipping, link to official Amazon listing)

Isopure Zero Carb Protein Powder (47 servings)

Brand website: $79.99 (free shipping, link)

Amazon: $74.26 (free shipping, link to official Amazon listing)

Walmart: $69.83 (free shipping, third-party seller, link)

Isopure protein supplements are currently around 10% cheaper on third-party retailers than at the brand's website.

However, the Walmart listing is from a third-party seller, so it may be safer to purchase Zero Carb Protein Powder from the official Amazon listing or the brand's website.

Pros and Cons of Isopure

Here are the pros and cons of Isopure in our opinion:


  • Zero Carb Protein Powder has no unhealthy ingredients
  • Zero Carb Protein Powder is only keto protein powder we've come across
  • Both products reviewed have effective protein dose for muscle building
  • Mostly positive online customer reviews


  • Somewhat expensive per serving
  • Protein Drink contains artificial flavors
  • Protein Drink contains artificial colors
  • Protein Drink contains an artificial sweetener
  • Doesn't appear to be clinically tested
  • Unclear if brand sourced from grass-fed animals
Stay up-to-date on our research reviews


In this article, we reviewed two Isopure protein supplements, and we consider one to be much better-formulated than the other. 

Isopure Protein Drink provides an effective protein dose for muscle building, but also contains a range of unhealthy additives including artificial flavors, artificial colors and an artificial sweetener.

Isopure Zero Carb Protein Powder provides an effective protein dose for muscle building, and has no additive ingredients that we consider to be unhealthy.

The Zero Carb Protein Powder is also the only protein supplement we've reviewed to date on Illuminate Health that contains 0 g of carbs per serving, so it may be a good option for keto dieters.

Individuals on low-carb, rather than keto, may benefit from considering other whey protein isolate supplements, because Isopure's Zero Carb Protein Powder has a relatively high price per serving.

Most of the online customer reviews of Isopure that we came across while researching this article were positive.

At the time of publishing this article, third-party retailers like Amazon and Vitamin Shoppe have better prices on one-time purchases of Isopure's products than the brand's website.