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Whey Protein Isolates

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What is whey protein isolate?

Whey protein isolate, usually shortened to WPI, is whey that has been filtered further than concentrate. The extra filtration strips out most of the fat and lactose, which lifts the protein content to roughly 90 per cent by weight against about 70 to 80 per cent for a concentrate. A standard 30 g scoop typically lands around 25 g of protein.

Two things follow from that filtration. It digests quickly and sits light, which is why it is the common pick straight after training or first thing in the morning. And with very little lactose left, people who find concentrate heavy on the stomach usually tolerate it better. The trade off is cost, since you are paying for the extra processing, and a thinner texture, because much of the flavour in a protein shake comes from the milk fat that isolate removes.

Why shop whey protein isolate at Supplement Mart?

  • 42 whey protein isolates in stock, across Australian and imported brands
  • 58 stores nationwide, with click and collect available
  • Free shipping Australia-wide on orders over $150, with no surcharges
  • East and west coast dispatch on orders placed before 2pm on weekdays
  • Supplement Mart Rewards, earning points on every dollar spent
  • An in-house nutritionist you can actually ask a question

How it is usually used

One scoop in 250 to 350 ml of cold water, shaken, after training or whenever protein is needed and food is not practical. Water keeps it fast and light; milk makes it creamier but adds back the lactose and fat that isolate was filtered to remove. Most people use one or two serves a day on top of meals rather than in place of them.

Frequently asked questions

What is the difference between WPI and WPC?

Filtration. Whey protein concentrate is around 70 to 80 per cent protein by weight and keeps more of the carbohydrate and fat from milk. Isolate is filtered further to roughly 90 per cent protein, with most of the lactose and fat removed. Concentrate tastes richer and costs less; isolate is leaner, lighter on the stomach and more expensive.

Is whey protein isolate suitable if I am lactose intolerant?

Usually, yes. The filtration that makes an isolate removes nearly all of the lactose, and most people with mild to moderate lactose intolerance handle it without trouble. It is not lactose free unless the label says so, and if you have a dairy allergy rather than lactose intolerance, a plant protein is the safer choice.

How much protein do I actually need?

The Australian Nutrient Reference Values set the recommended dietary intake at 0.84 g per kg of body weight per day for adult men and 0.75 g per kg for adult women. The International Society of Sports Nutrition suggests a higher range, 1.4 to 2.0 g per kg per day, for people doing regular resistance training. Both are linked under Sources below.

Should I mix it with water or milk?

Water if you want it fast, light and lowest in kilojoules, which is the usual choice after training. Milk if you want it thicker and more filling, which suits a breakfast or a between meals serve, at the cost of extra kilojoules and the lactose that was filtered out.

Does whey protein isolate help with fat loss?

Protein helps in a few indirect ways. It is more filling than carbohydrate or fat per kilojoule, and keeping protein high while in a deficit helps preserve muscle rather than losing it alongside fat. Isolate is useful here because it delivers protein with very little else attached. It does not burn fat on its own, and total daily intake is what matters.

Sources

Last reviewed: 10 October 2026