What is the lowest sugar whey that still scores high on the Index?
US live anchors: NutraBio WPI Index 96 at 0.0g sugar and $1.87 per 25g; Isopure Clear Citrus Lemonade Index 93 at 0.0g; Muscle Feast GF Isolate Chocolate Index 94 at 0.1g and $0.91. Sugar is 30% of Index.
What is the lowest sugar whey that still scores high on the Index?
Low sugar and a high Quality Index are related, not the same thing. Sugar is 30% of the Index. Formulation is 60%. Value (cost per 25g of protein) is 10%. A powder can sit at 0.0g sugar per 25g and still land middling if formulation checks fail or the scoop is expensive relative to the market.
Here are three live US product pages that combine verified low (or zero) sugar with Excellent Index scores.
Zero sugar, high Index: NutraBio and Isopure Clear
Two locks from product pages on 20 Sep 2026 (CEST) show 0.0g sugar per 25g protein and Excellent Index:
NutraBio Whey Protein Isolate
NutraBio Whey Protein Isolate (unflavored):
| Field | Live value |
|---|---|
| Quality Index | 96/100 Excellent |
| Cost per 25g protein | $1.87 |
| Sugar per 25g protein | 0.0g |
| Formulation checks | 6 of 6 |
Index leads at 96. Sugar is verified 0.0g per 25g on the product page. Cost per 25g is $1.87 on this listing.
Isopure Clear Citrus Lemonade
Isopure Clear Whey Isolate, Citrus Lemonade:
| Field | Live value |
|---|---|
| Quality Index | 93/100 Excellent |
| Cost per 25g protein | $2.22 |
| Sugar per 25g protein | 0.0g |
| Formulation checks | 6 of 6 |
Same verified 0.0g sugar band. Index 93 still clears Excellent (≥80). Cost per 25g is higher than NutraBio on today’s lock ($2.22 vs $1.87). Other Isopure packs and flavours can land differently; cite the URL you mean.
Near-zero sugar with strong Index and value
If you will accept a tenth of a gram of sugar for a lower protein cost, Muscle Feast Grass-Fed Whey Protein Isolate, Chocolate, 5 lb locked at:
| Field | Live value |
|---|---|
| Quality Index | 94/100 Excellent |
| Cost per 25g protein | $0.91 |
| Sugar per 25g protein | 0.1g |
| Formulation checks | 6 of 6 |
Index 94 sits between the two zero-sugar isolates above. Sugar is near-zero at 0.1g per 25g (still Excellent on the sugar panel). Cost per 25g is $0.91, the lowest of this trio.
Side by side
| Product | Index | $/25g | Sugar /25g |
|---|---|---|---|
| NutraBio WPI | 96/100 | $1.87 | 0.0g |
| Muscle Feast GF Isolate Choc 5 lb | 94/100 | $0.91 | 0.1g |
| Isopure Clear Citrus Lemonade | 93/100 | $2.22 | 0.0g |
Read Index first. NutraBio leads this set at 96 with verified 0.0g sugar. Muscle Feast is one Index point behind NutraBio at 94 with 0.1g sugar and the strongest $/25g. Isopure Clear matches the zero-sugar band at Index 93 with a higher protein cost on this pack.
Sugar thresholds in plain English
On How the Index works, the sugar component scores from sugar grams per 25g of protein:
- 0g → sugar component 100
- Above 0g through 2g → 80
- Above 2g through 4g → 60
- Above 4g through 7g → 40
- Above 7g through 10g → 20
- Above 10g → 0
Missing sugar data is never treated as zero. Product cards show sugar per 25g on the page. Tub “sugar free” marketing is a different claim; confirm the live sugar panel before you treat a listing as 0.0g.
Browse assist: sugar-free category and Compare
The sugar-free whey category is a useful browse list. Category membership and Unscored cards still need a product-page check for today’s Index and sugar per 25g. Open Compare to put finalists on one screen and sort by the axis you care about (Index, sugar, or $/25g).
Before you buy
Look up the powder on wheyindex.com. Read today’s Index first, then sugar per 25g and $/25g on the product page. Refresh if the listing has moved, then decide.