Whey and whey isolate comparison
Isopure Zero Carb 100% Whey Protein Isolate vs Optimum Nutrition Gold Standard 100% Isolate
Isopure Zero Carb and ON Gold Standard Isolate tie at 71/100 on our standard, with the same points on every criterion, so the label details below decide it. We could not verify a current price for Isopure Zero Carb, so we can't compare cost.
Both are scored out of 100 against our published standard: protein density, third-party testing, label transparency, sugar, ingredient simplicity and verified label data. Every number below is from the manufacturer's label; last checked 2026-10-13.
Isopure
Zero Carb 100% Whey Protein Isolate
Optimum Nutrition
Gold Standard 100% Isolate
Side by side
Per serving, from each label. Bold marks the better score, protein density, sugar and cost where the two differ. How we score
| Compared | Isopure Zero Carb | ON Gold Standard Isolate |
|---|---|---|
| Our score | 71/100 | 71/100 |
| Protein density | 30 / 3081% of each scoop is protein | 30 / 3081% of each scoop is protein |
| Third-party testing | 0 / 25No verified independent testing program | 0 / 25No verified independent testing program |
| Label transparency | 20 / 20Fully disclosed formula, no amino spiking | 20 / 20Fully disclosed formula, no amino spiking |
| Sugar | 10 / 100 g sugar per serving | 10 / 100 g sugar per serving |
| Ingredient simplicity | 6 / 10Mix of natural and artificial flavors or sweeteners | 6 / 10Mix of natural and artificial flavors or sweeteners |
| Verified label data | 5 / 57 of 7 label values verified | 5 / 57 of 7 label values verified |
| Type | Whey Isolate | Whey Isolate |
| Protein per serving | 25 g | 25 g |
| Serving size | 31 g (about 1 scoop) | About 1 Scoop (31g) |
| Protein by weight | 81% | 81% |
| Sugar | 0 g | 0 g |
| Calories | 110 | 110 |
| Cost per 25 g protein | Not verified | $2.35 |
| Price per serving | Not verified | $2.35 |
| Third-party certifications | None found | None found |
| Sweeteners | Sucralose | Sucralose |
| Allergens | Milk, Soy | Milk, Soy |
| Proprietary blend | No | No |
| Added free amino acids (amino spiking) | No | No |
| Last checked | 2026-10-13 | 2026-10-13 |
Which to choose
Only the differences in our records. A value we couldn't verify never counts as a difference.
Choose Isopure Zero Carb if…
On the label facts we track, Isopure Zero Carb has no clear edge over ON Gold Standard Isolate. Taste, how it mixes and the price where you shop may still decide it.
Choose ON Gold Standard Isolate if…
On the label facts we track, ON Gold Standard Isolate has no clear edge over Isopure Zero Carb. Taste, how it mixes and the price where you shop may still decide it.
The two powders
Good to know
Labels and prices change, so check the package before buying, especially if you have allergies. If you are pregnant, nursing, buying for a child or managing a health condition, ask your doctor before adding a supplement.