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Whey protein isolate / 2026

Most whey protein is sold on the front of the jar. We read the back.

Protein as a percentage of scoop weight. Sugar grams. Sweetener type. Filtration method. What the cow ate. Then the only number that matters at checkout: cost per gram of protein.
See the 2026 comparison
Read the ProEnergy review
Methodology

Six criteria, equally weighted

Each criterion scores from 0 to 10 and the six average to one decimal place. Nothing is weighted more heavily than anything else, which means a product cannot buy its way out of a bad ingredient list with a low price.
01

Protein purity

Protein as a percentage of scoop weight, and whether the form is isolate, concentrate, or a blend.

16.7%
02

Ingredient quality

Sourcing of the milk, filtration method, and how many ingredients exist purely to bulk the powder out.
16.7%
03

Sweetener profile

What supplies the sweetness, and how many grams of sugar and sugar alcohol come with it.
16.7%
04

Transparency

Panel clarity, published third-party testing, and how much the brand says about where the milk comes from.

16.7%
05

Taste and mixability

Drawn from aggregated buyer feedback across review platforms, not from our own palate.
16.7%
06

Value per gram

Cost per gram of protein at the best generally available price. Not cost per jar.

16.7%
We do not score on packaging, brand heritage, or how well a product markets itself. Full method on the About page.
Ranked

What we would actually buy

Three panels, in rank order. Where a figure has not been confirmed at source, the cell is left blank rather than filled with an estimate.

ProEnergy Whey Protein Isolate

EnergyFirst
.
Figures
verified
Rank
#1
Protein form
Isolate
Protein per serving
20 g
Sugar per serving
0 g
Sweetener type
Natural
Grass fed
Yes
Cost per gram of protein
$0.074/g
Overall score
8.8 /10
Cost per gram calculated at the case price of $54.99 for 37 servings of 20 g. Figures taken from the vanilla panel at energyfirst.com.

Whey Protein Isolate

Transparent Labs
.
Figures
verified
Rank
#2
Protein form
Isolate
Protein per serving
0 g
Sugar per serving
0 g
Sweetener type
Natural
Grass fed
Yes
Cost per gram of protein
$0.000/g
Overall score
0.0 /10

ISO100

Dymatize
.
Figures
verified
Rank
#3
Protein form
Isolate
Protein per serving
0 g
Sugar per serving
0 g
Sweetener type
Artificial
Grass fed
Unstated
Cost per gram of protein
$0.000/g
Overall score
0.0 /10
See all eight compared
Fundamentals

Isolate, concentrate, hydrolysate. The difference costs you money.

Concentrate

29% to 89% protein by weight
The cheapest form and the most common. Filtration stops early, so lactose, fat, and moisture stay in the powder. Most retail concentrates land near 70 to 80%, which means a fifth to a third of every scoop is not protein.

Isolate

90%+ protein by weight
Filtered further until almost everything that is not protein has been removed, which takes the lactose and the fat with it. It costs more per jar and mixes thinner in water. If you tolerate lactose poorly, this is the form that solves it.

Hydrolysate

Pre-digested, typically 90%+
Isolate broken into shorter peptide chains before it reaches you, which speeds absorption. The breakdown also exposes bitter compounds, so hydrolysates usually need heavier flavouring. You pay a premium for a difference most people cannot detect.
Read the full buyer's guide
Sourced

4,542 ratings, three platforms

Aggregate scores for EnergyFirst as published by each platform. They do not agree with each other, and the gap between them is more informative than any single figure.

4.8 /5
Shopper Approved
2,468 ratings
Collected by invitation after purchase, so the sample skews toward completed orders.
3.9 /5
SmartCustomer
2,067 ratings
A comparable sample size to Shopper Approved with a rating almost a full point lower.
4.0 /5
Trustpilot
7 ratings

Seven reviews. Too small a sample to read anything into, and we are not going to pretend otherwise.

Verbatim quotes pending source verification. We publish a quote only when we can link it to the review it came from, so this space stays empty until then. The aggregate figures above are taken directly from each platform.

What buyers report, in full
Read next
Buyer's guide
Six questions to ask before you buy
Form, sugar, sweetener, fat, gluten, and how much protein you actually need.
Use case
Twelve builds under 300 calories
What the satiety research shows, and the meal replacement maths behind it.
Recipes
Twelve builds under 300 calories
Macros computed from the ingredients, grouped by when you would drink them.
FAQ
Eighteen questions answered
Lactose, timing, stevia, storage, denaturing, and baking with whey.

Ready to try the isolate we ranked first?

ProEnergy ships free over $50 and carries a full money-back guarantee on the unused portion. Case pricing brings it to $1.49 per 20 g serving.
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