Isopure: Brand Review

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Isopure Zero Carb’s defining number is 100 calories per scoop — and every one of those calories comes from 25g of whey protein isolate. No carbs. No sugar. 0.5g fat. This makes it the benchmark choice for anyone on strict keto, managing lactose sensitivity, or wanting the highest protein density per calorie in a mainstream powder.

Quick summary

The benchmark ultra-lean whey isolate — 25g protein, 100 calories, 0g carbs, Informed Choice certified. The right product if you need zero-carb protein purity. Priced at a premium over concentrates.

  • Zero Carb: 25g protein, 100 calories, 0g carbs, 0g sugar per scoop — 100% protein calories
  • 100% whey protein isolate — no concentrate filler, no carbs
  • Trace lactose only (<1g per serving) — suitable for most lactose-intolerant users
  • Informed Choice certified — batch-tested for banned substances
  • Flavor profile thinner than concentrate-based powders — inherent to isolate processing

Isopure Zero Carb Whey Isolate

25g protein, 100 calories, 0g carbs

The Data

The Pro Tip

The Unflavored version is actually unflavored — not “mild vanilla” the way most so-called unflavored powders are. That makes it the right pick for cooking and baking where sweetener-flavored protein would clash, and for smoothies where you want zero flavor interference. It also tends to run cheaper per serving than the flavored options.

The Honest Critique

Thinner flavor profile than concentrate-based powders. The microfiltration that removes carbs and fat also strips some natural flavor compounds. Isopure flavors consistently taste thinner and less rich than concentrate-based proteins mixed at the same volume. This is an inherent property of pure isolate, not a quality defect — but buyers switching from Gold Standard or similar will notice the difference. Use milk rather than water if this matters to you.

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Isopure Low Carb

Same isolate base, 3g carbs, added vitamin blend

The Data

The Pro Tip

The added vitamins make Low Carb a better fit than Zero Carb if you’re using protein powder as a daily meal replacement. The micronutrient coverage adds functional value that Zero Carb doesn’t provide.

The Honest Critique

The 3g carb difference rarely matters in practice. For anyone following a low-carb diet that isn’t strict competition keto, 3g carbs per serving is nutritionally negligible. Pay for the Low Carb version only if you specifically want the vitamin addition — not because the 3g-versus-0g carb difference will affect your results.

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Isopure Infusions

20g protein in a clear, fruit-flavored format

The Data

The Pro Tip

Serve over a full glass of ice and drink immediately. Infusions is designed to be consumed like a sports drink — the flavor quality drops noticeably at room temperature.

The Honest Critique

Lower protein than Zero Carb at a comparable price. At 20g per serving versus 25g, you’re getting 20% less protein for a similar outlay. Infusions fills a real niche for anyone who actively dislikes milky shakes, but if you’re buying it as a straight swap for Zero Carb without registering the protein difference, you’re getting worse value.

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Buyer’s Guide: Is Isopure Right for You?

1. Zero Carb makes sense if you’re on strict keto or tracking carbs tightly. There’s no other mainstream isolate that reliably delivers 0g carbs per serving. For anyone not on strict carb restriction, the practical difference between Isopure and a quality whey concentrate is marginal — and concentrate is substantially cheaper. See our best protein powder roundup for the comparison.

2. Check whether pure isolate is actually necessary for your goals. People who tolerate dairy well absorb whey concentrate and isolate with essentially equal effectiveness. Isolate’s advantages — lower lactose, higher protein density — matter for specific goals. If those goals don’t apply to you, you’re paying a premium without benefit.

3. Informed Choice certification is batch-tested, not just formula-tested. This distinction matters for athletes in tested sports. A formula can be clean without any individual batch being tested. See our safety testing guide for the full breakdown.

FAQ

How much protein is in Isopure Zero Carb?

25g protein per scoop, 100 calories, 0g carbs, 0g sugar. The protein source is 100% whey protein isolate. One of the leanest protein-to-calorie ratios available in a mainstream powder.

Is Isopure lactose-free?

Less than 1g of lactose per serving — trace amounts only. Most people with lactose intolerance handle it without issue. Not suitable for those with a dairy protein allergy. For fully dairy-free options, see our dairy-free protein powder guide.

Is Isopure certified for athletes?

Yes — Informed Choice certified (batch-tested for banned substances and label accuracy). Appropriate for competitive athletes in tested sports. See our safety testing guide for the full breakdown.

Can I use Isopure on keto?

Yes. Zero Carb delivers 0g carbohydrates per serving — it fits any ketogenic macro split. Low Carb’s 3g carbs are compatible with most non-strict keto approaches.

What’s the difference between Isopure Zero Carb and Low Carb?

Zero Carb: 0g carbs, 100 calories, no added vitamins. Low Carb: 3g carbs, 110 calories, extended vitamin and mineral blend. Both use the same 100% whey isolate base. Choose based on whether the micronutrient addition is worth the small carb increase to you.

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Last reviewed: by the protein.supply editorial team.