How much protein should you take a day?

The reference meta-analysis puts the ceiling of the benefit at around 1.6 g per kilo of body weight a day, with an interval reaching 2.2. For a 70 kg person that is about 112 g a day counting all food, not just shakes. Going beyond that has not been shown to add more muscle.

Do you have to take it right after training?

It is not critical. The meta-analysis on timing concludes that what explains the differences between studies is total daily protein, not whether the shake came at thirty minutes or at two hours. The narrow anabolic window is a convenient myth for selling shakes.

Does protein make you fat?

It makes you fat as much as its calories do, like any food. A scoop of whey is around 100-120 kcal. In fact it is one of the most filling macronutrients and the one that burns the most energy to digest.

Does whey harm the liver or kidneys?

In healthy people there is no evidence that a high protein intake harms the kidneys or liver. With a diagnosed kidney disease protein is controlled, but that is prescribed by a doctor.

Is whey or isolate better?

For most people, concentrate is better value per gram of protein. Isolate makes sense with lactose intolerance, on very tight cuts or if it upsets your stomach. They are compared separately on this site precisely because they do not carry the same protein per kilo.

Home / Whey protein (concentrate) / Guide

Whey protein (concentrate) · Strong evidence

What whey protein is for and how much to take

The short answer. Whey does not build muscle because it is whey: it does so by getting you to your daily protein total, which is the figure that really matters. A meta-analysis of 49 studies finds that supplementing protein, on top of the same training without supplements, adds little in absolute terms, and that the benefit stops growing at around 1.6 g per kilo of body weight a day. It is convenient, cheap food, not a drug.

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.

Effects of whey protein with their source
Effect	How much	Detail
Ceiling of the daily dose	1.6 g/kg/day	Above that figure the meta-analysis finds no further gain (the interval reaches 2.2). For 70 kg that is about 112 g of protein a day counting all food, not just shakes. It is the most useful figure on this whole page. [1]
Strength (1RM)	+2.49 kg	What the supplement adds over training without it. It is not what you gain from training: most of the result comes from the training, and this is the extra you can attribute to the tub. [1]
Lean mass	+0.30 kg	Small, and it should read as small. It is the difference attributable to the supplement in people who already train and already eat. [1]
Dose per serving	20 to 40 g	The range where the ISSN places maximal protein synthesis per serving. It takes 700 to 3000 mg of leucine, which 20-25 g of whey covers easily. [2]
Timing of the serving	barely relevant	The half-hour anabolic window does not hold up: the meta-analysis on timing concludes that the differences are explained by total daily protein, not the clock. [3]

02 How to take it

Dose. 20 to 40 g per serving. What counts is the daily total: 1.4 to 2.0 g per kilo of body weight.
When. Whenever it suits you to reach the total. Before, after or between meals.
How long before you notice it. Weeks or months, and only with strength training behind it.

Details that change the result

A kilo of concentrate is not a kilo of protein: it is around 75 %. That is why the price per kilo of tub and the price per kilo of actual protein are not the same number, and why this site splits concentrate and isolate into two tables.
If you already reach your protein from food, a shake adds nothing. It is a convenient and usually cheap way to get there, not a requirement.
Protein powder is no more "chemical" than chicken: it is filtered and dried milk whey.

03 When it makes sense and when it does not

Worth it if

You struggle to reach 1.6 g per kilo from food, which is very common on cutting diets.
High training volume and little time to cook.
Cutting with low calories: protein keeps you full and protects lean mass.
Vegetarian diet with little complete protein.

Not worth it if

You already reach the daily total with food. Then the shake is spending, not gaining.
Marked lactose intolerance: isolate carries much less.
If it is expected to replace meals. It adds to the total; it is not a meal.

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. 49 estudios, 1863 participantes. 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
Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013;10:53. doi:10.1186/1550-2783-10-53

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 protein

Answered with the data on this page

How much protein should you take a day?: The reference meta-analysis puts the ceiling of the benefit at around 1.6 g per kilo of body weight a day, with an interval reaching 2.2. For a 70 kg person that is about 112 g a day counting all food, not just shakes. Going beyond that has not been shown to add more muscle.
Do you have to take it right after training?: It is not critical. The meta-analysis on timing concludes that what explains the differences between studies is total daily protein, not whether the shake came at thirty minutes or at two hours. The narrow anabolic window is a convenient myth for selling shakes.
Does protein make you fat?: It makes you fat as much as its calories do, like any food. A scoop of whey is around 100-120 kcal. In fact it is one of the most filling macronutrients and the one that burns the most energy to digest.
Does whey harm the liver or kidneys?: In healthy people there is no evidence that a high protein intake harms the kidneys or liver. With a diagnosed kidney disease protein is controlled, but that is prescribed by a doctor.
Is whey or isolate better?: For most people, concentrate is better value per gram of protein. Isolate makes sense with lactose intolerance, on very tight cuts or if it upsets your stomach. They are compared separately on this site precisely because they do not carry the same protein per kilo.

And now, which to buy

Prices, kept apart from the evidence

This page explains what whey protein does and deliberately names no brand. The comparison is the other half: 251 products from 17 stores from €20.00 per kg, sorted by price and by how verifiable their certification is.

See the whey protein (concentrate) comparison

Other guides

What each supplement does, with its sources