Protein powder

Concentrated protein from milk or plants, taken mostly for muscle and strength.

People take it for

Strength and muscle
Weight and body fat
Staying strong with age
Walking and getting about

A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.

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What is protein powder?

Protein powder is protein taken out of a food, dried, and sold by the tub. Most of it comes from milk, as whey or as casein, with beef and egg white the other animal sources and peas, rice, soy and hemp the plant ones. It is mixed into water, milk or a smoothie, plain or flavoured. People buy it because it is a quick, inexpensive way to add a known amount of protein to the day, which is why it has spread well beyond the gym.

Why do people take protein powder?

Strength and muscle

The thinking. Resistance training breaks muscle protein down, and the protein eaten around a session is the material it is rebuilt from. Reviews describe a clear rise in muscle rebuilding when protein is taken before or after training, and a shake is the simplest way to be sure it arrives.

What research has found. Meta-analyses pooling dozens of training trials, one of them 49 studies and 1,863 adults, measured muscle size and strength and found bigger gains with a supplement than with training alone. The difference shrank with age and stopped once total daily protein reached about 1.6 grams per kilogram of body weight. A fair body of trials has looked at this, and most point the same way.

Weight and body fat

The thinking. Eating fewer calories tends to take muscle away along with the fat. The thinking is that keeping protein high while the rest of the diet comes down leaves less reason for muscle to be broken down.

What research has found. A review of fourteen trials in adults with obesity eating fewer calories measured fat-free mass and found it broadly held, most often where resistance exercise was part of the plan; several found no difference. A small trial in older women taking whey alongside supervised training found a greater fall in body fat than training with a placebo. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.

Staying strong with age

The thinking. Muscle mass and strength fall away with age, and the trials here were run mostly in older adults who had already lost muscle or were becoming frail. The thinking is that a measured scoop tops up the day’s protein without asking anyone to eat a bigger meal.

What research has found. Seven reviews and two trials measured muscle mass and strength; most found more of both when a supplement was added to resistance training. One large review of 36 studies in healthy, non-frail older adults found no clear difference, its authors noting that those taking part were already eating enough protein. A reasonable number of trials have measured this, and most of them agree.

Walking and getting about

The thinking. What matters day to day is not muscle size but what it allows: walking at a decent pace, getting out of a chair, carrying shopping. So part of the research has measured movement itself, which is what people have in mind when buying a tub for an older parent.

What research has found. Two reviews and one trial measured walking speed, chair rises and grip strength in older adults. One review found faster walking but no change in muscle mass or strength; another found lean-mass gains that tracked with leg strength; a trial in frail adults found better physical performance with no change in muscle mass. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.

What does protein powder do in the body?

Protein is a chain of amino acids. Digestion takes the chain apart, the amino acids arrive in the blood, where trials measuring them record a rise after a shake, and the body uses them to build and repair its own tissue, muscle included. A powder does nothing a plate of food would not; it delivers a known amount, quickly.

Around exercise, reviews describe a marked rise in muscle protein synthesis, the rebuilding process, when protein is taken shortly before or after a session; that is the basis for the habit of a shake afterwards. The same reviews are clear that total protein and calories across the whole day matter more than the timing of any single serving. The source changes the mix of amino acids: whey, used in most of the older-adult research, is high in essential amino acids and particularly leucine.

What do people say about taking protein powder?

These are anecdotes people have shared, not evidence.

What people like

Very commonly, people say a shake keeps them full to the next meal and settles the mid-afternoon urge to snack.
Convenience comes up in nearly every thread: a known amount of protein on a busy morning, with no cooking.
Many find hitting a protein target from meals alone surprisingly hard, and use a scoop to close the gap.
A smaller group take it around training, for recovery after weights, and find the lighter, clearer versions most refreshing.

Common complaints

Digestive trouble is the commonest complaint by far: bloating, wind and stomach upset, usually blamed on whey or the sweeteners.
Taste and texture come up constantly: shakes going thick or slimy, sweet flavours turning cloying, plant versions tasting earthy.
A steady minority object on principle, calling powders ultra-processed and arguing that meat, fish, dairy and pulses do the same job.
Cost draws regular grumbles, and several warn that leaning on shakes as meal replacements ends in eating it all back.

How people take it

One scoop a day is the usual pattern, most often at breakfast or straight after the gym; a few take two.
Mixed with water, or with dairy, soya, oat or almond milk, and often blended with frozen berries, banana or ice.
Stirring it into yoghurt or skyr is very common, and some cook with it in porridge, overnight oats or pancakes.
Ready-made bottled drinks suit some who dislike mixing powder, though most note they cost considerably more per serving.

Read from these public discussions:

Protein powder - guide me plz! (Mumsnet, 2025)
Protein powder/shakes (Mumsnet, 2025)
Anyone here in good shape - and NOT using protein powders? (Mumsnet, 2024)
Protein powders (Mumsnet, 2023)
Protein shakes (Mumsnet, 2023)

What forms of protein powder are there?

Form	What’s different	Per serving, on products we list
Whey concentrate	A tub sold as plain whey protein, with no further wording, is concentrate.	20 g to 23 g
Whey isolate	Whey processed a step further, leaving less of what is not protein.	26 g
Whey hydrolysate	Whey whose protein chains have already been partly broken down.	not in our price tables yet
Whey blend	A stated mix of concentrate and isolate; the ratio is rarely given.	not in our price tables yet
Milk protein	Protein from milk as a whole rather than one fraction of it.	not in our price tables yet
Casein	The family of milk proteins that clusters into micelles.	not in our price tables yet
Beef protein	Protein from beef rather than milk, often sold as an isolate.	not in our price tables yet
Egg white protein	Protein from egg white, also labelled albumen or egg albumin.	not in our price tables yet
Soy protein	A plant protein with well-balanced amino acids, comparable to animal protein.	not in our price tables yet
Pea protein	Protein from yellow peas, sold alone or as the base of a blend.	not in our price tables yet
Rice protein	Protein from brown rice, most often seen alongside pea protein.	not in our price tables yet
Hemp protein	Protein from hemp seed, labelled hemp or hemp seed protein.	not in our price tables yet
Vegan protein blend	Most vegan tubs are a pea-and-rice blend, not a single plant source.	not in our price tables yet

What else is worth knowing about protein powder?

Labels give protein per serving, and a serving is often two or three scoops; the protein share of the powder varies, so two tubs of the same weight can hold very different amounts.
Trials used a wide range, from 15 grams twice a day in frail older adults to 35 grams a day alongside training, and reviews found no further gain in fat-free mass beyond about 1.6 grams per kilogram of body weight a day.
A review of protein for muscle loss and frailty reported no serious adverse events, and a dose-comparison trial in frail older adults reported none that were harmful.
Nearly all of these studies used whey or milk protein, with soy in a couple of reviews; the beef, egg, pea, rice and hemp powders on sale did not appear among them.

If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.

The research behind this page (23 studies)

How much does protein powder cost?

That depends on the form and the pack, so we work out the price of the same dose of every protein powder product we can find and rank them.

Compare protein powder prices per dose