Isopure Zero Carb vs Transparent Labs Grass-Fed Whey Isolate
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Isopure is the convenience-tier zero-carb isolate — 25g protein, $1.40–1.80 per serving at typical sizes, widely available on Amazon, and includes an Unflavoured version. Transparent Labs is the clean-label premium — 28g protein, grass-fed sourcing, no artificial sweeteners, dual Informed Choice + Informed Protein certification. Pick Isopure if you want maximum value per gram of protein with zero carbs; pick Transparent Labs if grass-fed and clean-label are non-negotiable.
Isopure Zero Carb
25g protein per serving. 100% whey isolate. 0g carbs, 0g sugar, 100 calories. Informed Choice certified. Includes Unflavoured version. Widely available.
Check current price on Amazon →Transparent Labs Grass-Fed Whey
28g protein per serving. 100% grass-fed whey isolate. No artificial sweeteners, colours, or preservatives. Informed Choice + Informed Protein certified.
Check current price on Amazon →At a glance
- Both are 100% whey isolate at premium-tier spec
- Isopure: 25g protein, 0g carbs, 100 cal, Informed Choice — the cleanest macro spec
- Transparent Labs: 28g protein, grass-fed, no artificial additives, Informed Choice + Informed Protein — the cleanest ingredient spec
- Isopure has an Unflavoured version for cooking; Transparent Labs uses stevia-only sweetening
- Transparent Labs has 12% more protein per serving but costs $0.30–0.60 more per serving at typical sizes
Head-to-Head
| Isopure Zero Carb | Transparent Labs Grass-Fed Whey | |
|---|---|---|
| Protein per serving | 25g | 28g |
| Calories per serving | 100 | 120 |
| Carbs per serving | 0g | 1g |
| Sweetener | Standard supplement sweeteners | Stevia only |
| Artificial colours/preservatives | Yes (varies by flavour) | None |
| Grass-fed sourcing | Not claimed | Yes |
| Certification | Informed Choice | Informed Choice + Informed Protein |
| Unflavoured option | Yes | No |
| Brand-direct price | Varies (mid-market) | $59.99 / 30 servings (transparentlabs.com May 2026) |
Isopure Zero Carb
The data: 25g protein per scoop, 100 calories, 0g carbs, 0g sugar. 100% whey protein isolate. Informed Choice certified. Available in 8 flavours plus an Unflavoured version that stirs into Greek yoghurt, oatmeal, or savoury food without adding sweetness. Multiple tub sizes; larger sizes are more cost-efficient.
Who it’s for: Strict macro trackers and keto dieters who need true zero-carb protein at mid-market pricing. Anyone who wants an Unflavoured version for cooking or stirring into food. Buyers who value Amazon availability and consistent retail presence over premium ingredient claims.
The honest critique: No grass-fed sourcing claims. Uses standard supplement-industry sweeteners (acesulfame-K, sucralose) and artificial colours in some flavours. The zero-carb formula has no thickeners — water-thin by design. Informed Choice is solid but is less than Transparent Labs’s dual certification stack.
Isopure on Amazon →Transparent Labs Grass-Fed Whey Isolate
The data: 28g protein per scoop, sourced from 100% grass-fed cattle whey isolate. Stevia and natural flavours only — no artificial sweeteners, colours, or preservatives. Informed Choice certified for banned substances and Informed Protein certified for content verification. From transparentlabs.com, May 2026: $59.99 for 30 servings. 21 flavours.
Who it’s for: Buyers who want the most rigorous clean-label whey isolate — grass-fed, no artificial additives, and protein content independently verified. Anyone whose buying criteria explicitly include grass-fed sourcing. Buyers who want both Informed Choice (banned substances) and Informed Protein (content accuracy) certifications.
The honest critique: Per-serving cost is at the upper end of the mainstream isolate range. Stevia divides buyers — some find it cleaner, others find it less effective at masking the whey base. No Unflavoured version — limits the use case to shakes and smoothies rather than savoury cooking applications.
Transparent Labs on Amazon →Which Should You Buy?
Choose Isopure if
- You’re strict keto and need true zero-carb protein
- You want the Unflavoured version for cooking applications
- Cost-per-serving matters more than clean-label sourcing
- Informed Choice certification alone is sufficient
Choose Transparent Labs if
- You want grass-fed sourcing and no artificial additives
- You want the higher 28g protein per serving
- Dual Informed Choice + Informed Protein certification matters
- You prefer stevia-based sweetening
FAQ
Is Transparent Labs worth the extra cost over Isopure?
Worth it if you specifically want grass-fed sourcing, no artificial sweeteners, and dual Informed Choice + Informed Protein certification together. Transparent Labs costs $59.99 for 30 servings — typically $0.30–0.60 more per serving than Isopure at similar sizes. If clean-label isn’t a priority, Isopure delivers an equivalent zero-carb spec at lower cost.
Which has more protein per serving?
Transparent Labs — 28g per serving versus Isopure’s 25g. Across a tub, the difference adds up to meaningfully more total protein in Transparent Labs.
Does Isopure use grass-fed whey?
Isopure does not publicly claim grass-fed sourcing. Transparent Labs publishes grass-fed sourcing as a core product claim. If grass-fed is non-negotiable, Transparent Labs is the only choice between these two.
Are both certified for tested athletes?
Yes — Isopure carries Informed Choice and Transparent Labs carries both Informed Choice and Informed Protein. Both cover banned-substance testing for drug-tested athletes. Transparent Labs adds independent verification that the labelled protein content matches what’s in the tub. See our safety testing guide for the full breakdown.
Related Resources
- Read the full Isopure brand review
- Read the full Transparent Labs brand review
- See our best protein powder guide for picks across all categories
- See Dymatize vs Isopure for the hydrolyzed vs standard isolate comparison
- See ON vs Transparent Labs for the benchmark vs clean-label comparison
- Read protein powder without artificial sweeteners for more clean-label options
Last reviewed: by the protein.supply editorial team.