Perfect Sports Diesel Whey Isolate Review (2025): Grass-Fed NZ Protein—Taste, Macros, Price & Verdict

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I have managed a supplement store for more than a decade, and I have used protein powders as a coach and athlete for nearly twice as long. 

This first hand experience gives me both personal experience and professional insight into what makes a great protein powder. 

Diesel by Perfect Sports has been a number one selling protein powder in my store for years, with their immense flavor variety and commitment to quality being the top reasons for consumer satisfaction.

In this article I will dive through the various pros and cons of Diesel Whey Isolate to help you decide if it’s worthy of a spot in your supplement stack.

Key Takeaways:

Honest Review Guarantee from FeastGood: Our testing team purchases each product 100% independently and uses the product for several weeks up to several months before writing a review. Learn more about our review process here.

• Diesel uses exclusively grass-fed whey isolate and offers 26-27g of protein and 110-120 calories per scoop. 

• Diesel costs between $1.93 and $2.25 per serving, depending on which size you buy, which is around the average cost per serving for similar protein powders on the market

• Diesel is third party tested and does not use any artificial flavors, sweeteners, or colors in its formula

Before We Begin

The first thing I want to highlight first and foremost is that Perfect Sports has several protein powders that look similar. I want to distinguish between them before moving forward.

Diesel New Zealand Whey Isolate

This is the product that I am testing for this article, and will refer to it as Diesel protein going forward for clarity. This is a high quality whey isolate that uses grass-fed whey sourced from New Zealand. This protein uses no artificial flavors or colors, but does use sucralose . This is a sugar-free product that has a very high protein percentage and is likely suitable for individuals with lactose sensitivities.

Perfect New Zealand Whey Protein

Very similar to Diesel, the key here is that Perfect Protein still uses high quality whey protein from New Zealand with no artificial flavors or colors, but this is not an isolate protein. This product uses whey concentrate which has slightly higher levels of carbs and fats that have not been filtered out. 

Perfect Sports Ultra Fuel:

This is the value-focused protein powder by perfect sports. It does not use grass-fed New Zealand Whey, and it does use artificial sweeteners (sucralose).

About Perfect Sports

Perfect Sports is a Canadian company that is committed to quality through third-party testing and creating products without the use of artificial flavors and colors. 

Some of their products do use sucralose as a non-nutritive sweetener, but their flagship product (and the one we are reviewing today), Diesel Grass-Fed Whey Isolate, uses only stevia and natural flavors in its formula. 

In a world that is becoming increasingly eco-driven, consumers are putting pressure on supplement companies to show their commitments to sustainability. 

Perfect Sports has stepped up to the plate, with containers that are made from recycled plastic. Their containers and lids can be recycled by removing the product label and placing your products in bins. 

The Perfect Sports facility uses electricity that is generated using more than 90% non carbon-based power and uses a diverse mix of technologies for power generation like wind, solar, and water. 

Alongside their collection of whey protein powder, Perfect Sports manufactures a vegan protein powder, as well as a whole line of performance-based products like pre-workouts, amino acids, electrolytes, and fat loss support products. 

Perfect Sports has a blog on their website, but the most recent article appears to be from 2023. 

The same goes for their recipe page, however I highly recommend checking it out anyways because there are some delicious seasonal protein powder recipes that are applicable all year round.

Overview of Diesel Protein Powder

Diesel is made using only whey isolate sourced from grass-fed New Zealand cows. Diesel is available in 18 different flavor varieties, all sweetened with stevia. Diesel is gluten free, peanut and nut free, contains no artificial flavors or colors, and is Informed Choice certified.

The macronutrient breakdown of Diesel Whey protein is: 

• Protein: 26-27g  
• Carbohydrates:  0g
• Fat:  0g
• Sugar: 0g

At Feastgood.com, we have the following criteria to classify protein percentages: 

• Excellent: 85% protein per scoop or higher 
• Good: 75 to 84% protein per scoop
• Reasonable: 65 to 74% protein per scoop
• Unacceptable: Below 65% protein per scoop

Diesel Protein has 110 to 120 calories per serving. With 26 to 27g of protein, Diesel offers between 86% and 98% protein per scoop, putting all flavors in the “Excellent” category. 

This great protein percentage is attributed to the fact that Diesel only uses whey isolate, which is whey protein that has had the carbs and fats filtered out. 

Among the highest protein percentages are French Vanilla, Cookies and Cream, Strawberry, Banana, Salted Caramel, Mocha Latte Cappuccino, Honeydew Melon Bubble Tea, and Brown Sugar Bubble Tea.

Diesel protein offers 86-98% protein per scoop, making it an “Excellent” protein source.

Highlights: What I Liked About Diesel Protein

All-Natural Ingredients

Diesel uses exclusively grass-fed whey isolate and does not use any artificial flavors, sweeteners, or colors in its formula. 

While a lot of brands are now turning to more natural non-nutritive sweeteners like stevia or monk fruit, Diesel has been a pioneer in this area and has done this for more than a decade. 

Tons of Flavor Variety

Diesel is currently available in 18 flavor varieties and comes out with seasonal flavors like Pumpkin Spice Latte and Chocolate Cream Egg. 

While a lot of protein powder brands have switched to using more natural non-nutritive sweeteners like stevia and monk fruit, Diesel has managed to do so with 18 different flavors. 

There are traditional flavors like chocolate and vanilla, but also unique flavors like brown sugar bubble tea and mocha latte cappuccino which increases the likelihood that you will find a flavor you like. 

Good for Lactose Sensitivity

Diesel contains 0g of sugar, which means it contains no lactose. This makes it a suitable option for individuals with lactose sensitivity.

Note that Diesel is still made from whey protein which comes from dairy. Individuals who have dairy allergies and not just sensitivities may still experience negative side effects from Diesel. 

If you follow a vegan diet or have a dairy allergy, I suggest trying Perfect Sports Diesel® Vegan instead.

Third-Party Tested

Diesel is Informed Choice certified, which means it undergoes third-party testing for quality and purity. 

This Informed Choice certification is required for the athletes of some athletic organizations, and is an added level of reassurance that their products are free from banned substances. 

For the general athletic population, this adds security that your protein powder is free of contaminants and does actually contain the ingredients that it claims to. 

Drawbacks: What I Didn’t Like About Diesel Protein

Cost*

Diesel protein costs between $1.93 and $2.25 per serving, which is higher than the average cost of whey protein which falls closer to $1.35 per serving. 

That being said, when we compare the cost per serving of Diesel to other natural, third-party tested protein powders the playing field is much more level. 

Transparent Labs and Legion Whey both offer similar quality products (no artificial flavors, grass-fed whey, third-party tested) at the same $2.00 per serving. 

*In Canada, we have seen a massive increase in the cost of Diesel Protein and it is now one of the most expensive proteins per serving on retail store shelves. While inflation has hit whey protein powders hard across the board internationally, Perfect Sports has had some of the highest price increases. The cost for Diesel protein in Canada is between $2.11 and $3.33 making it among the highest cost per serving for whey protein among Canadian brands. 

Stevia can have an undesirable taste

Some people find that stevia has a bitter aftertaste. Because it is so much sweeter than table sugar, some individuals also find stevia-sweetened products to be too sweet.  

I do find some of the Diesel flavors to be very sweet without having a really strong flavor, which ends up with a weird combination of them being both sweet and bland. 

This is a very subjective experience, however, so it’s always worth testing out the flavors on your own. Even though there are some flavors that I am not a huge fan of (like Milk Chocolate which is one that I find bland), there are others that I really enjoy like Triple Milk Chocolate and Brown Sugar Bubble Tea.

Diesel Protein Review: My Experience

I have been fortunate as both a supplement store manager and a Canadian to have had access to Diesel’s full flavor line up for nearly a decade. I don’t normally get this amount of hands-on experience using a protein powder. 

Diesel was one of the first companies to really go all-in on using New Zealand whey protein and avoiding the use of artificial flavors and sweeteners. While there are a lot of companies now, like Transparent Labs, who offer third-party tested all-natural protein powders, Diesel was really ahead of its time. 

Since Diesel has 0g of sugar per serving, it can be inferred that it is lactose free (since lactose is a sugar). As such, Diesel should be a suitable option for anybody who has a lactose sensitivity. 

As someone with a lactose sensitivity, I always found that I tolerated Diesel well with no gassiness, bloating, or discomfort. 

Diesel mixes up really well with no chalkiness or clumps and I find it really easy to mix just with water, but also into smoothies, oatmeal, and yogurt. 

One of my absolute favorite ways to have Diesel though is to mix the Brown Sugar Bubble Tea flavor with water and a splash of almond milk, and then add my own tapioca boba pearls into it. This has taken my summer obsession with bubble tea from a 400+ calorie, high sugar drink to a 150 calorie, high protein one. 

I will say that overall, if I have one complaint about Diesel protein powder it’s actually the flavor. I enjoy the Brown Sugar Bubble Tea flavor I just mentioned, and I enjoy the fruitier flavors like Pineapple Mango and Honeydew Melon Bubble Tea. I find the traditional flavors like vanilla, milk chocolate, and chocolate peanut butter to lack in overall flavor. 

They don’t taste bad by any stretch, I just find the overall flavor itself to be lacking. This could come down to the way that stevia itself tastes for me personally, but I find that many flavors of Diesel are sweet without being rich or flavorful. 

This is also a very subjective aspect to the powder. I like my proteins to be really rich and flavorful. I know that many people are the opposite and prefer their proteins to have a more mild taste. 

Ultimately, with more than a dozen flavors to choose from, it’s incredibly likely that you will be able to find at least one – likely more – that you enjoy and can integrate into your day. 

How Does Diesel Stack Up Against Our Criteria For Whey Protein

We have used the following 7 key criteria for ranking whey protein powders.  Here’s how Diesel Protein stacked up:

Nutrition label transparency 

Our rating: 5/5

Diesel clearly labels the calories, carbs, protein, and fat per serving according to National food guide standards. 

Since Diesel is Informed Choice certified, it has to undergo regular third-party testing for quality and purity. You can find a list of the tested batches with their corresponding lot numbers here. 

Effective ingredients 

Our rating: 5/5

Diesel protein uses only New Zealand Grass-Fed Whey Isolate in their formula. They avoid using artificial flavors and colors. 

New Zealand cattle are pasture-raised, which improves the overall quality of life of the cattle used. It has been theorized that whey from grass-fed cows has higher nutrient content, but the consensus seems to be that by the time the milk gets filtered into whey protein, there is little to no difference between grass-fed and alternately-fed whey. 

That being said, New Zealand Grass-Fed Whey is guaranteed to be free of hormones and antibiotics.   

Diesel is lactose-free, peanut and nut free, and gluten-free. 

Protein percent of calories

Our rating: 5/5

Diesel offers 26-27g of protein per serving and has 110-120 calories. This means that Diesel offers between 86 and 98% protein per scoop, putting all flavors in the “Excellent” category for protein percentage. 

Diesel uses exclusively whey isolate, which has had the naturally occurring fat and sugar content of the dairy removed. 

Through additional levels of filtration, Diesel offers a protein that contains zero sugar and zero fat, resulting in a protein powder with an excellent protein percentage.

Taste/flavor

Our rating: 4/5

Diesel offers a ton of flavor variety, with 18 different flavors currently available. I personally find some of the flavors to be a little dull when mixed with just water, but the vast selection makes it likely that everyone can find a flavor that works for them.

Diesel is one of the top selling protein powders in my store and has been for years. Even though I personally find some of the flavors a bit dull, there are still 3 or 4 that I enjoy enough to consume regularly. 

Many customers appreciate the lighter flavor, since they find a lot of protein powders sickeningly sweet. The lighter flavors also make Diesel easy to add to recipes like smoothies or baking without having the protein completely dominate the flavor. 

Mixability

Our rating: 4.5/5

Diesel mixes up with no clumps or chalky texture. 

I did find that when it was left for a few minutes, the protein did separate with some starting to settle at the bottom. This was easily remedied by gently swirling the protein bottle between sips to redistribute the powder. 

Texture (Thick or Thin)

Our rating: Thin

Diesel mixes up with a very thin texture, which is a common feature of whey isolates.

Satiety

Our rating: 1/5

Diesel uses exclusively whey isolate, which is a low calorie and fast-digesting protein source. I found that I got approximately 1 hour of satiety after having Diesel.

On its own, Diesel is a low calorie whey isolate. It makes a great post-workout option since the protein can be digested quickly to support muscle recovery. 

It doesn’t lend itself to feelings of satiety or fullness, especially if it is just mixed with water. 

You can add Diesel to a meal, or combine it with other food sources like yogurt or oatmeal to increase the feelings of satiety from that meal/snack. 

Who Is Diesel Protein For? 

Diesel protein is for: 

• Someone who wants to avoid any artificial flavors, sweeteners, and colors

• Individuals who are sensitive to lactose

• Those who like a lot of flavor variety

• Those looking for a post-workout protein or who just want to add more protein to their day

Who Shouldn’t Take Diesel Protein?

Diesel protein is not for: 

• Individuals who can’t tolerate any dairy or follow a vegan diet

• Those who want a rich, dessert-like protein powder

• Individuals who want their protein powder to provide prolonged satiety

Diesel Protein Customer Reviews

Like I mentioned above, some customers and I definitely have differences of opinion when it comes to the taste and mixability of Diesel protein.

That being said, on the Diesel website, they boast a 4.69 out of 5 star rating with more than 5,000 reviews which is a pretty generous sample size. The reviews on large online retailers like Costco and Amazon have very similar ratings, with 4.7 and 4.5 out of 5 stars, respectively.

Many reviews praise the clean ingredients of the product and users have found a variety of ways to integrate the protein into their day, by mixing it into coffee or blending it with various fruits as smoothies. 

Many users feel that the protein digests well and a lot of individuals comment on how they appreciate that the flavor isn’t too sweet. If you are someone who tends to find protein powders to be unbearably sweet, then there’s a good chance you will also appreciate the more subtle taste of Diesel Whey. 

Where To Buy Diesel Protein? 

In the United States, your key retailers include The Vitamin Shoppe, Amazon, and Muscle & Strength. 

International shoppers can find the retailer closest to them by using the Where To Buy feature on the Perfect Sports website.  Perfect Sports has retailers in the US, Canada, Asia, Latin America, The Middle East, and Europe.

Frequently Asked Questions

Where Is Diesel Whey Made? 

Diesel Protein is manufactured in Canada, in Vaughan Ontario, in a cGMP (current Good Manufacturing Practices) licensed facility.

What Is Perfect Sports’s Shipping Policy? 

Products ordered from the Perfect Sports website can only be shipped within Canada, with different tiers to get free shipping depending on your location. International buyers will be subject to the shipping policy of the third party retailer.

What Is Perfect Sports’s Return Policy? 

Items ordered through third party retailers must be returned to that retailer. Items purchased directly from Perfect Sports can be returned if they are unopened, within 30 days of purchase. Full details on returns and refunds can be found here.

Is Diesel Protein Gluten Free?

Diesel Protein is gluten-free.

Is Diesel protein good for muscle building?

Yes, Diesel is a high-quality whey isolate that delivers 26–27g of fast-digesting protein per scoop with no extra carbs or fats. It’s third-party tested and Informed Choice certified, making it a clean, reliable option to support muscle repair and growth.

Are There Any Side Effects?

Diesel Protein is a pure whey isolate with 0g of sugar, making it lactose-free. This should make it safe for use by most individuals with no negative side effects. It is still a dairy-based product, however, and may still be reactive to those with dairy allergies.

How To Contact Perfect Sports

Perfect Sports has a contact page that allows you to filter your reason for inquiry and submit a message directly via that page. 

While browsing their shipping and returns page, I did find the e-mail address shop@perfectsports.com that you can contact for returns and exchanges. 

To connect on a more casual level, find Perfect Sports online on Facebook (last updated in 2023), Instagram, X (zero posts here), TikTok, and Youtube.