Head to head · Protein Powder
Isopure Zero Carb Whey Protein Isolate vs Transparent Labs 100% Grass-Fed Whey Protein Isolate
Transparent Labs scores higher overall (8.8 vs 7.8 out of 10) and leads on four of the five factors we score.
Updated September 2026 from our full reviews · How we score
A true zero-carb whey isolate: 25 g of protein plus a broad vitamin and mineral blend in a 110-calorie scoop, at a price above most rivals.
We may earn a commission when you buy through these links — it never affects our scores. How we make money
A grass-fed whey isolate with 28 g of protein per scoop, stevia instead of artificial sweeteners, and NSF Certified for Sport status.
We may earn a commission when you buy through these links — it never affects our scores. How we make money
We may earn a commission when you buy through these links — it never affects our scores. How we make money
The short answer
Choose Isopure if…
- Keto and strict low-carb diets
- People who want added vitamins and minerals
- Those who prefer a less-sweet vanilla
Choose Transparent Labs if…
- Drug-tested athletes
- Clean-label shoppers avoiding artificial sweeteners
- People who want grass-fed sourcing
- Lactose-sensitive lifters
- You care most about quality & purity, value, experience, transparency
Side by side
| Zero Carb Whey Protein Isolate | 100% Grass-Fed Whey Protein Isolate | |
|---|---|---|
| Our score | 7.8 / 10 | 8.8 / 10 |
| Efficacy (30%) | 8.9 | 9.1 |
| Quality & Purity (25%) | 7.4 | 9.4 |
| Value (20%) | 6.8 | 7.4 |
| Experience (15%) | 7.8 | 8.6 |
| Transparency (10%) | 7.8 | 9.5 |
| Form | Powder | Powder |
| Serving | 1 scoop (31 g)40 servings per container | 1 scoop (34.9 g)30 servings per container |
| Price per serving | See retailer | $2.17 |
| Testing & certifications | cGMP facility | NSF Certified for SportInformed Choice |
| Dietary | Gluten-free, Sugar-free, Keto-friendly | Gluten-free |
| Key ingredients |
|
|
| Flavors | 6 (Creamy Vanilla, Cookies & Cream, Strawberries & Cream…) | 8 (Milk Chocolate, French Vanilla, Dark Chocolate…) |
| Creator video reviews | 4 | 5 |
Pros and cons
Zero Carb Whey Protein Isolate
- 25 g of protein with 0 g carbs and 0 g sugar per 110-calorie scoop
- All of the protein comes from whey protein isolate
- Broad vitamin and mineral blend, including 100% of the Daily Value for vitamin B12
- Large review base on Amazon (4.6 stars from more than 13,000 ratings)
- No third-party banned-substance certification found; testing is done in-house
- About $2.24 per serving for the 40-serving tub, and more on the brand site
- Contains soy lecithin, sucralose, artificial flavor and xanthan gum
- Flavor and texture draw mixed feedback, with some reviewers calling it gritty or bland
100% Grass-Fed Whey Protein Isolate
- 28 g of protein per scoop from grass-fed whey isolate
- Listed in NSF's Certified for Sport database and certified by Informed Choice (per the brand)
- Every ingredient disclosed by weight, with batch test results published online
- No artificial sweeteners, dyes or preservatives
- buyers frequently describe it as easy on the stomach
- About $2.17 per serving for the 30-serving tub, well above whey blends
- Stevia can leave an aftertaste some people dislike
- Made on equipment that also processes eggs, soy, wheat, shellfish, fish oil, tree nuts and peanut oil, and some flavors contain peanuts
- Mostly sold through the brand site and Amazon, so in-store discounts are rare
Our verdicts
Zero Carb Whey Protein Isolate
Isopure Zero Carb does exactly what the name promises: 25 g of isolate protein with no carbs or sugar, plus a vitamin and mineral boost. It is a sensible pick for strict low-carb and keto eaters, but the lack of third-party certification, the artificial sweetener and a price well above rivals such as ISO100 keep it out of the top tier.
Full review
100% Grass-Fed Whey Protein Isolate
For shoppers who prioritize ingredient transparency and third-party verification, this is one of the strongest whey isolates available: 28 g of protein, a short stevia-sweetened ingredient list, NSF Certified for Sport status and public batch testing. The trade-off is price, at more than $2 per serving, and stevia's flavor will not suit everyone.
Full review
What creators say
Questions people ask
Is Isopure better than Transparent Labs?
Are Isopure and Transparent Labs third-party tested?
Who should choose Isopure over Transparent Labs?
More protein powder comparisons
Whey+ Grass-Fed Whey Protein Isolate vs 100% Grass-Fed Whey Protein Isolate
Clear Whey Isolate vs 100% Grass-Fed Whey Protein Isolate
Whey Protein vs 100% Grass-Fed Whey Protein Isolate
Whey+ Grass-Fed Whey Protein Isolate vs Clear Whey Isolate
Whey Protein vs Whey+ Grass-Fed Whey Protein Isolate
Whey Protein vs Clear Whey Isolate
See all protein powder, ranked