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After testing more than 70 protein powders, we named the Onnit Grass-Fed Whey Isolate one of the best protein powders in our best whey protein powders roundup and our overall best protein powders list. With callouts like that, you’re probably wondering what makes it so special.

In this Onnit Grass Fed Whey Isolate review, we’ll share more about our experience with this protein powder, getting into details about what we like and what we don’t. We’ll also dig deeper into the company’s shipping and return policies to help you decide if you want to try it for yourself.

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. GGR also recommends choosing a product that has been third-party tested for quality.

We’ve Tested More Than 100 Protein Powders

Next to creatine and pre-workouts, protein powders are one of the most popular sports nutrition supplements. Because of this, our GGR testers, which include nutrition coaches, certified personal trainers, and professional athletes, took our duties very seriously and tested more than 100 of them ourselves. We rated them on several factors, like taste, solubility, formulation, and price (everything’s laid out in our supplement testing methodology), sharing both the good and the bad parts of our experience with you.

We rated each factor on a scale of 1 to 5, also including:

  • Customer service
  • Customer reviews
  • Third-party testing

Onnit Grass-Fed Whey Isolate

Onnit Whey Protein

GGR Score: 4.4 starstarstarstarstar

Product Highlights

  • Sourced from New Zealand grass-fed cows
  • Made with whey protein isolate to filter out fats and carbs
  • Offers a complete amino acid profile
  • Website offers a subscription option to save money and auto-ship

Pros & Cons


  • Low in carbs
  • High in leucine
  • Whey isolate gets to muscles faster
  • Non-GMO


  • High cost per serving
  • Can cause digestive issues for some people
  • The Mexican Chocolate flavor has mixed reviews

Bottom Line

Onnit Whey Protein is a great protein option for those looking for a grass-fed protein, however there are cleaner grass-fed protein powders on the market that are lower in cost.

A Quick Look at Onnit Grass-Fed Whey Protein Isolate

Onnit is a U.S.-based company that manufactures all its supplements in Austin, Texas. It may not seem very creative, but their main philosophy is that “you are what you eat,” and they take the stance that everyone can benefit from including high-quality supplements, like the Grass-Fed Whey Protein Isolate, in their diet.

Because ingredient quality is one of Onnit’s brand values, they have rigorous standards for sourcing and third-party testing. This protein contains only natural ingredients and is free from artificial sweeteners, flavors, and colors.

At 20 grams of protein per scoop, it’s not as concentrated as we’d like—we typically like to see 25 to 30 grams of protein per serving for a whey protein—but 20 grams is still enough to support muscle-building and weight loss1.

Before You Buy 

  • This is an isolate, but it has some added ingredients, like MCTs, that affect its macro breakdown.
  • There are only two flavors, but many reviewers say the vanilla is the best they’ve had.
  • You can save 15% if you order directly through the brand’s site and subscribe for a recurring shipment.

Is Onnit Protein Powder Worth It?

“Is it worth it?” can be a really subjective question. At $2.00 per serving, it’s a premium supplement, but we think it’s worth it for those looking for a high-quality protein powder with additional gut support.

At the end of the day, just like everything else we recommend, we think this protein powder is great for some people and not so great for others. 

Great for:

  • Competitive athletes who want peace of mind from third-party testing
  • People who need additional gut support
  • Anyone looking for a highly bioavailable, high-quality protein

Not recommended for:

  • Those on low-carb or strict macro diets looking for a pure whey protein isolate
  • Shoppers on a tight budget
  • People looking for a really concentrated whey protein powder

Onnit Grass-Fed Whey Isolate Specs

Price per serving$2.00
Serving size1 scoop (29.2 grams)
FlavorsVanilla, Mexican chocolate
Protein 20 g
Carbs3 g
Fat2 g
SweetenersStevia, monk fruit extract
Third-party tested?Yes

Experience Using Onnit Grass-Fed Whey Protein Isolate

Certified sports nutrition coach, certified personal trainer, and fitness product testing expert Amanda Capritto tried the Onnit Grass-Fed Whey Protein Isolate over the course of a couple of weeks, rating it on things like price, formulation, taste, solubility, side effects, and third-party testing. Here’s how it stacked up.

Price Per Serving

If you purchase this protein powder directly from the website, it comes out to $2.00 per serving. This is slightly higher than some of the others we tested but still falls within the expected range. Typically, you’ll pay around $1.30 to $2.50 per serving for a whey protein, and since this is grass-fed, being on the higher side makes sense.

testing protein powders main feature photo

Onnit does have a subscription option on their website so if you want to sign up for recurring deliveries you can save 15%, bringing the price down to $1.70 per serving.


This is a relatively clean whey protein powder that’s gluten-free and made without artificial sweeteners and colors. Onnit uses only natural flavors and sweeteners, like stevia and monk fruit extract. There are some filler ingredients, like maltodextrin, but these help keep the protein powder shelf-stable and there are fairly minimal fillers compared to other protein powders.

The non-GMO protein is derived from the milk of grass-fed dairy cows that were treated in accordance with Animal Welfare Approved standards. And research shows that grass-fed dairy has higher levels of omega-3 fatty acids and conjugated linoleic acid (CLA)2 and lower levels of omega-6s. This ratio not only combats inflammation, but CLA has been shown to increase endurance and delay perceived exertion during exercise3.

This protein powder is a whey isolate, not a whey concentrate, which means most of the lactose, fat, and carbohydrates have been filtered out. Even still, the fat and carb content is a little higher than you typically see with whey isolates (but not as high as whey protein concentrate). It has 20 grams of highly bioavailable animal-based protein, 2 grams of fat, and 3 grams of carbohydrates.

RELATED: Onnit Plant-Based Protein Review

There are some additional ingredients, like medium-chain triglycerides and sunflower oil powder, that you don’t typically see in whey protein isolates, so these are what’s affecting the macros. There are also probiotics and digestive enzymes added for some extra digestive support.

Amanda gave it a 4.5 out of 5 for formulation since the macros are still pretty good and these added ingredients can be beneficial for those who want to prioritize gut health. 

Taste and Solubility 

The Onnit protein powder gets mixed reviews for taste and solubility. Amanda gave it a 3.75 out of 5 for taste and a 5 out of 5 for solubility. 

A woman drinks from a shaker bottle

She tried the Mexican chocolate and said the flavor was “good,” and that it actually does taste different than other chocolate protein powders. (FYI Mexican chocolate is made with cinnamon for a little hidden kick under the chocolate flavor). The texture was extremely thin, though, especially when it was mixed with water, which is why some points got knocked off. Amanda noted that it is richer when mixed with whole or oat milk. It could also be a good option for smoothies.

RELATED: Best-Tasting Protein Powder

As for solubility?

“This dissolves great—almost too well! It’s so thin when mixed with water. There are no clumps whatsoever,” Amanda said.

Side Effects

As far as side effects go, there’s nothing to note. Amanda tried this protein powder on three separate occasions and didn’t experience any digestive upset or other reactions to it. Because of this, this protein powder got a rating of 5 out of 5 here, too.

Third-Party Testing 

When it comes to third-party testing, Onnit is on it. Amanda gave them a 5 out of 5 in this category. The company opts in to various certifications, including Informed Sport, which means the products have been tested for (and found to be free of) substances that are banned in professional sports and athletic competitions. They’re also tested for purity.

Onnit Grass-Fed Whey Protein Isolate vs Transparent Labs Whey Isolate 

Transparent Labs Whey Isolate

Transparent Labs 100% Grass-Fed Whey Protein Isolate

GGR Score: 4.2 starstarstarstarstar

Product Highlights

  • High-quality whey protein isolate
  • 28 grams of protein per serving
  • 15 flavors to choose from
  • $1.99 per serving

Pros & Cons


  • High-quality protein
  • No artificial sweeteners, food dyes, or preservatives
  • Lots of flavors to choose from
  • Good customer reviews
  • Whey isolate may be easier to digest for some people


  • Price per serving on the high end

Bottom Line

Our testers love Transparent Labs 100% Grass-Fed Whey Protein Isolate because we know exactly what's in it, and almost every flavor we've tried is a 5 out of 5 on taste. Yes, it's a little more expensive than other protein powders but you get what you pay for.

Transparent Labs Whey Isolate is one of our favorite whey proteins because it’s high-quality and great-tasting. It’s also excellent for post-workout and pre-workout, which is partly why we named it the best whey protein for muscle gains. There are a lot of similarities between these two options, but there are notable differences, too. One of the biggest is their macro content. 

While both are whey isolates, the Onnit Whey has 20 grams of protein, 2 grams of fat, and 3 grams of carbohydrates. The Transparent Labs whey has 28 grams of protein, zero grams of fat, and 1 gram of carbohydrates. This may seem negligible, but it can make a difference for those who are on a low-carb diet or closely tracking their macros.

And while the Onnit protein has probiotics and digestive enzymes added, the Transparent Labs protein is pure protein. Here’s a chart breaking down the specs side by side, but you can also read our full Transparent Labs protein review if you want more details.

Onnit Whey IsolateTransparent Labs Whey Isolate
Price per serving$2.00$2.00
Serving size1 scoop (29.2 grams)1 scoop (32.96 grams)
FlavorsVanilla, Mexican chocolateMilk chocolate, French vanilla,
chocolate peanut butter, milk chocolate chip,
vanilla peanut butter, strawberry milkshake,
dark chocolate, oatmeal chocolate chip cookie,
cinnamon French toast, sugar cookie, mocha,
peanut butter, vanilla oatmeal cookie,
blueberry pancakes, unflavored
Protein 20 grams28 grams
Carbs3 grams1 grams
Fat2 grams0 grams
SweetenersStevia, monk fruit extractStevia
Third-party tested?YesYes

Customer Experience 

Onnit is pretty generous with their returns, but the policy depends on which supplement you get. For the whey protein, you’ll have 90 days to return it if you don’t like it. To get a full refund, it has to be at least half full. Otherwise, they’ll give you a store credit. Returns outside of the 90-day window are also eligible for a store credit.

Ordering Onnit Whey Protein 

You have two options when ordering: a one-time purchase or a subscription. Subscriptions can be set up for as little as a week to as much as 90 days, with several options in between. If you subscribe, you’ll get 15% off each order.

An image of Onnit grass-fed whey

Shipping is free if you spend at least $100; otherwise, you’ll have to pay a shipping fee dependent on your zip code.

You can also get this protein powder from Amazon. If you do, you’ll be subjected to their shipping and return policies.

RELATED: Best Protein Powder on Amazon

Customer Reviews

Overall, customers are happy with the Onnit whey protein. It has an average of 4.3 out of 5 stars on Amazon and the brand’s site. Most of the negative commentary is around the thin texture and the price. Some also say the vanilla flavor is a little too strong and it overpowers everything. There are also some recent negative reviews saying that the formula changed and isn’t as good now. 

But reviewers mostly like it, saying that it blends well and it’s easier to digest thanks to the probiotics and enzymes. Some also like the thinner texture, saying they prefer to add it to smoothies or protein shakes and like that it doesn’t make them too thick.

Final Verdict of Our Onnit Grass-Fed Whey Isolate Review

We thought the Onnit Grass-Fed Whey Isolate was pretty good. It wasn’t the best-tasting protein powder we’ve ever tried, but it was good enough and it scored some extra points since it’s sourced from grass-fed cows. We also liked the addition of probiotics and digestive enzymes for those who want additional gut support.

  • It’s pricey, but as some reviewers say, “You get what you pay for.”
  • It’s a good choice for those who need gut support in the form of probiotics and digestive enzymes.
  • The macros are a little off for a whey isolate, so it may not be the best for those on a strict macro diet.

Full Rating

Onnit Grass-Fed Whey Protein

Onnit Whey Protein is a great protein option for those looking for a grass-fed protein, however there are cleaner grass-fed protein powders on the market that are lower in cost.

Product Brand: Onnit

Product Currency: $

Product Price: 59.95

Product In-Stock: InStock

Editor's Rating:

Onnit Grass-Fed Whey Protein Isolate Rating

Price per serving – 2.25
Formulation – 4.5
Taste – 3.75
Solubility – 5
Side effects – 5
Third-party testing – 5
Customer service – 5
Customer reviews – 4.7
Buy Now

Onnit Grass-Fed Whey Protein: FAQs

How long is Onnit Protein Powder good for?

Onnit provides a manufactured date for each of its products. The protein powder is good for two years after that date.

Is Onnit Grass-Fed Whey Protein better than plant-based protein?

In my opinion, yes. Plant-based and vegan protein powders have their place, but when it comes to bioavailability4 (which in turn, has major effects on muscle growth and workout recovery), you can’t beat a high-quality whey protein powder.

Does grass-fed whey build muscle?

Yes, just like other quality protein supplements, grass-fed whey protein can help with muscle gain and increasing muscle mass because it’s rich in branched-chain amino acids (BCAAs), most notably leucine 5. Keep in mind that when it comes to building muscle, you need to focus on your total protein intake. Grass-fed whey can be a good supplement to help you get there, but you need to make sure you’re hitting those protein macros (and weight training).

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.


1. Kadam, B, Ambadkar, R, Rathod, K, Landge, S. Health Benefits of Whey: A Brief Review. Int. J. Livest. Res. 2018;8(4):1. doi:10.5455/ijlr.20170411022323

2. Alothman, M, Hogan, SA, Hennessy, D, et al. The “Grass-Fed” Milk Story: Understanding the Impact of Pasture Feeding on the Composition and Quality of Bovine Milk. Foods. 2019;8(8):350. doi:10.3390/foods8080350

3. Terasawa, N, Okamoto, K, Nakada, K, Masuda, K. Effect of Conjugated Linoleic Acid Intake on Endurance Exercise Performance and Anti-fatigue in Student Athletes. J Oleo Sci. 2017;66(7):723-733. doi:10.5650/jos.ess17053

4. Berrazaga, I, Micard, V, Gueugneau, M, Walrand, S. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients. 2019;11(8):1825. doi:10.3390/nu11081825

5. Duarte NM, Cruz AL, Silva DC, Cruz GM. Intake of Whey Isolate Supplement and Muscle Mass Gains in Young Healthy Adults when Combined with Resistance Training: a Blinded Randomized Clinical Trial (Pilot Study). J Sports Med Phys Fitness. 2020;60(1):75-84. doi:10.23736/S0022-4707.19.09741-X

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