# Whey, Casein or Plant Protein: Which Powder Should You Buy?

> Concentrate, isolate, casein, pea: the real differences, how to read a label, and how to work out the price per gram of protein.

- Source: [Musku](https://website.musku.app/), free strength training tracker for iPhone and Android
- Canonical URL: https://website.musku.app/blog/whey-casein-plant-protein-powder
- Published: 2026-09-09
- Updated: 2026-09-09
- Level: Beginner, Intermediate
- Language: English
- French version: https://website.musku.app/fr/blog/proteine-en-poudre-whey-caseine-vegetale
- Author: Musku (Julien Legrand)

_Informational content: this is not a substitute for medical advice. Check with a doctor before starting a training program, especially if you have a health issue or any pain._

The protein aisle is designed to confuse you. Fifteen brands, five types of powder, names promising revolutionary absorption, and a threefold price spread for essentially the same contents. Here is how to cut through it, starting from one simple idea: protein powder is not a supplement, it is a food.

## What a powder is, and is not

Protein powder is milk or plant matter, filtered, dried and flavoured. It does not build muscle on its own. It only helps you reach your [daily protein target](https://website.musku.app/blog/protein-per-day-build-muscle) when cooking is inconvenient. If you already hit that target with food, you need nothing.

Which leads to a useful rule: judge a powder like a food, on three criteria only. Its actual protein content, how well you digest it, and its price per gram of protein. Everything else is packaging.

## Whey: concentrate, isolate, hydrolysate

Whey is the by-product of cheesemaking. It is the reference option because it is well absorbed, rich in leucine, and cheap.

| Type | Protein | Lactose | Who for |
| --- | --- | --- | --- |
| Concentrate | 70 to 80 % | Present, 4 to 8 % | Everyone, by default |
| Isolate | 85 to 92 % | Near zero | Lactose intolerance, strict cutting |
| Hydrolysate | 85 to 90 % | Near zero | Nobody, barring a medical reason |

Concentrate is the sensible default. Isolate costs 30 to 50 % more for a genuine benefit in one case only: if lactose bothers you. Hydrolysate is pre-digested, which speeds absorption by a few minutes and has never been shown to build more muscle. Its price, however, is entirely real.

## Casein: slow, but not magic

Casein is the other milk protein. It clots in the stomach and digests over five to seven hours, against one to two for whey. Hence the classic bedtime shake argument.

The effect is real: around forty grams of casein before sleep does increase overnight protein synthesis. But the magnitude is modest, and it only matters much if your overall intake is borderline. Greek yoghurt or quark contain the same casein, cost less, and have the advantage of being actual food.

Verdict: worth it if you like the thick texture and want a filling snack. Not a separate pillar of your strategy.

## Plant proteins

Pea, rice, soy, hemp, or blends. The question is not whether they work, it is how much you take. Plant proteins are generally a little lower in leucine, the amino acid that triggers muscle building, and often short on one specific amino acid: pea tends to lack methionine, rice lacks lysine.

Two practical consequences:

- **Choose a blend** rather than a single source. Pea and rice complement each other well.
- **Increase the dose by around 25 %.** Where 25 g of whey does the job, count on 30 to 35 g of plant powder for a comparable stimulus.

At matched doses, the results converge. We go deeper into this in our guide to [building muscle without meat](https://website.musku.app/blog/building-muscle-plant-based).

## Reading a label in thirty seconds

1. **Look at protein per 100 g of powder**, not per serving. A brand advertising "24 g of protein" in a 40 g scoop is selling you 60 % protein, so plenty of sugar or thickeners.
2. **Check the reference serving size.** It ranges from 25 to 40 g between brands, which makes every front-of-pack comparison useless.
3. **Read the ingredient list.** It should fit in a few lines. Blends padded with cheap amino acids often exist to inflate the stated figure.
4. **Ignore the marketing terms.** "Cold micro-filtered", "anabolic matrix", "rapid absorption": none of these has a regulated definition.

## The only calculation that matters

Compare price per 100 g of protein, not price per kilo of powder. The formula fits on one line: **bag price divided by the grams of protein it contains, multiplied by 100**.

| Source | Rough cost per 100 g of protein |
| --- | --- |
| Whey concentrate, large bag | 3 to 4 € |
| Eggs | 4 to 6 € |
| Chicken breast | 4 to 5 € |
| Quark, skyr | 5 to 7 € |
| Premium branded isolate | 6 to 9 € |

Prices vary by country and by promotion, but the ranking barely moves. A bag selling for twice as much per kilo rarely holds twice the protein. This is the calculation that saves you the most money, and it takes ten seconds in the shop.

## When powder does nothing for you

If you already eat 1.6 to 2.2 g of protein per kilo of bodyweight, adding a shake changes nothing. If you are trying to lose fat, powder is still calories: it helps when it replaces a fattier food, not when it stacks on top of everything else. And if you struggle to eat enough calories, powder is a poor tool; a real meal does that job better.

## Frequently asked questions

### Is whey bad for your kidneys?

In people with healthy kidneys, no study has shown harm from a high protein intake, powder included. If you have a diagnosed kidney condition or a risk factor, though, your protein intake should be set by your doctor or a dietitian, not by an article or a label.

### Can you take whey without training?

Yes, it is simply another protein source. It will not make you gain weight on its own and will not make you lose it either: it counts towards your daily calories like any food.

### Do I need my shake right after training?

No. Your muscle stays sensitive to protein for several hours after a session. A meal within two to three hours is plenty, and the shake is purely a matter of convenience.

### Are sweetened powders a problem?

At the doses found in a shake, approved sweeteners are considered safe by food safety authorities. Some people digest them poorly, particularly polyols: if you get bloating, try an unflavoured version or another brand before concluding that protein does not agree with you.

The real trap with protein powder is believing it solves a training problem. It only solves a grocery problem. What actually moves you forward is what ends up in your log: loads going up, sets adding up, sessions stacking week after week. In Musku, those are the numbers you watch change over time, and no shaker will ever replace them.