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Whey protein isolate · Strong evidence
Whey isolate: how it differs from concentrate
The short answer. Isolate and concentrate rest on the same evidence: it is the same whey protein, filtered more times. The difference is not in what it does in the muscle, but in what the tub contains: more protein per kilo and almost no lactose or fat. That makes it useful in a few specific cases and an unnecessary expense in the rest.
Several meta-analyses or position stands from scientific societies agree that there is an effect. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.
01 What it does and how much
Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.
| Effect | How much | Detail |
|---|---|---|
| Protein per kilo of product | ~88 to 90 % | Against ~75 % for a concentrate. It is the only difference you can measure without asking anyone, and it is why the two categories do not share a table: on price per kilo of tub, concentrate always wins by carrying more filler. [3] |
| Lactose | almost none | The extra filtering removes lactose and fat. It is the real reason many people tolerate it better. [3] |
| Effect on strength and lean mass | the same | Gram for gram of protein, there is no demonstrated advantage of isolate over concentrate in healthy people who train. What counts is still the daily total. [1][2] |
| Ceiling of the daily dose | 1.6 g/kg/day | The same as for any protein source. Switching from concentrate to isolate does not move this figure. [1] |
02 How to take it
- Dose. 20 to 40 g per serving; the daily total is still 1.4 to 2.0 g per kilo.
- When. Same as concentrate: whenever it suits you to reach the total.
- How long before you notice it. Weeks or months, and only with strength training behind it.
Details that change the result
- Always compare the price per kilo of PROTEIN, not per kilo of tub. An isolate at €30/kg with 88 % protein is cheaper per gram of protein than a concentrate at €27/kg with 75 %.
- If your stomach has no issues and you do not count every gram, concentrate is usually the sensible buy.
- Hydrolysate is something else: pre-digested protein. It is absorbed a little faster and there is no evidence that this translates into more muscle.
03 When it makes sense and when it does not
Worth it if
- Lactose intolerance or heavy digestion with concentrate.
- Cutting with very tight calories, where every gram of fat and sugar in the tub matters.
- Athletes with strict weight control who need protein with as little else as possible.
Not worth it if
- You tolerate concentrate well and do not count macros to the gram: you are paying a premium for nothing.
- You are trying to gain weight: then the fat and carbs in concentrate are not a waste, they add up.
04 Sources
Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.
- Morton RW et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. doi:10.1136/bjsports-2017-097608
- Jager R et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. doi:10.1186/s12970-017-0177-8
- de Wit JN. Nutritional and functional characteristics of whey proteins in food products. J Dairy Sci. 1998;81(3):597-608. Los aislados parten del 90 % de proteina y los concentrados comerciales van del 35 % al 80 %. doi:10.3168/jds.S0022-0302(98)75613-9
This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.
Questions about whey isolate
Answered with the data on this page
- Is it worth paying more for isolate?
- Only if it solves something specific for you: lactose, digestion or very tight macros. Gram for gram of protein there is no evidence it builds more muscle than concentrate. Before deciding, look at the price per kilo of protein, not per kilo of tub: sometimes isolate comes out the same or cheaper on that count.
- Is isolate absorbed faster?
- Somewhat faster, yes, because it carries less fat and lactose. But that speed has not translated into more muscle mass in the studies: what matters is total daily protein.
- Is isolate suitable if I am lactose intolerant?
- It is usually well tolerated because the filtering leaves almost all the lactose out, normally below 1 g per serving. A milk protein allergy is different: there the problem is the protein, not the sugar, and isolate is no good.
And now, which to buy
Prices, kept apart from the evidence
This page explains what whey isolate does and deliberately names no brand. The comparison is the other half: 182 products from 14 stores from €26.99 per kg, sorted by price and by how verifiable their certification is.
Other guides
What each supplement does, with its sources