Do I need protein shakes to build muscle, and are they safe?

1. Protein is a nutrient, not a training programme

Protein supplies amino acids, the building blocks used to make and maintain tissues. Some amino acids must come from food because the body cannot make them. Protein is therefore necessary even if you never visit a gym. “Do I need protein?” and “Do I need extra protein?” are different questions.[2]

Resistance training provides a reason for muscles to adapt. Protein supplies material for that process, but a shake does not reproduce the training stimulus. Early strength gains also reflect learning to recruit muscles more effectively, not just larger muscles. A change in lifting performance and a change in muscle size are related but different outcomes.[11]

The useful comparison is usually training with an adequate diet versus the same training with additional protein. It is not protein versus no protein: people in control groups still eat. Supplement trials therefore cannot establish that powder is essential, or that someone already eating enough will gain the same additional benefit as someone with a shortfall.[4]

2. Basic needs, training targets and calculations

EFSA's population reference intake for adults is 0.83 g per kilogram of body weight per day. This is an intake intended to cover the needs of most healthy adults, not a promise of maximum muscle growth. It applies to protein from a mixed diet, including animal and plant sources.[1]

The International Society of Sports Nutrition position statement gives 1.4–2.0 g/kg/day for most exercising people seeking to build or maintain muscle. This is a sports-nutrition range, not a compulsory minimum for everyone who lifts weights, and not an established safety ceiling. Training load, existing diet and the goal matter. This dossier does not prescribe specialist diets for aggressive weight loss or medical conditions.[3]

These are simple multiplications, not measurements of individual need. For example, 75 × 1.6 = 120 g in the entire day. If a hypothetical food diary already supplies 100 g, the arithmetic gap is 20 g, not another 120 g. Food could fill that gap; a shake is only one option. The decimal precision in the table does not mean anyone needs to weigh protein that precisely.[1][3]

Count ordinary meals, bread, grains, legumes, dairy or alternatives, snacks and drinks. Check the protein amount on the label rather than the weight of the powder: a scoop of product is not necessarily an equal weight of protein. A dietitian can help when body weight, appetite, restrictive eating or a medical condition makes a simple multiplication misleading.[2][8]

3. How much does extra protein add?

Morton and colleagues' 2018 systematic review combined 49 randomised studies with 1863 participants. Both comparison groups performed resistance training; one received additional protein. Training interventions lasted 6–52 weeks. Different training programmes, ages, protein sources and starting diets were combined, so this is an average across varied circumstances.[4]

These are between-group differences in gains. They do not mean the supplement group gained only 0.30 kg altogether, nor that everyone gains that amount each month. The confidence intervals describe uncertainty around an average, not the range of results every individual should expect. The comparison groups were placebo or no-supplement groups, not people deprived of dietary protein.[4]

Fat-free mass is an especially important wording distinction. A body-composition measurement is not a direct weighing of newly built muscle. The review also examined muscle-size outcomes, but those measurements came from fewer studies and some were sensitive to study inclusion. “A modest additional benefit alongside training” is more defensible than a promise of rapid muscle growth from powder.[4]

4. Diminishing returns, not a hard ceiling

The same review estimated a point beyond which further protein was not associated with further fat-free-mass gains: 1.62 g/kg/day. The estimated breakpoint had a wide 95% confidence interval of 1.03–2.20 g/kg/day. The model's improvement over a straight line was not conventionally statistically significant: p = 0.079.[4]

That makes roughly 1.6 g/kg/day a useful evidence-informed reference, not a biological switch. This was a model comparing study groups, not a trial assigning every participant to closely spaced doses to discover their personal optimum. The upper end of the confidence interval is not a requirement, and the breakpoint is not a kidney-safety limit.[4]

Nor does the result mean the body stops absorbing protein above that amount. Protein has uses beyond enlarging muscles and can provide energy. The relevant question is whether adding still more produces a worthwhile training benefit. Once intake is adequate, a more expensive shake or a larger serving need not solve a disappointing training result.[2][4]

5. Food, plant protein and whey

Protein can come from beans, lentils, tofu, tempeh, nuts, grains, eggs, fish, meat and dairy. Ordinary food can meet sports-related requirements; powders offer convenience rather than a separate biological category of muscle-building nutrition. Whey is a milk protein, not an anabolic drug. Choosing it can be practical, but choosing not to use it is also compatible with building muscle.[2][3]

Plant proteins differ in digestibility and essential-amino-acid composition. A varied intake, including legumes and grains, helps cover those differences. Voedingscentrum advises attention to protein quality and a higher basic intake for fully vegan diets. That basic dietary advice should not simply be stacked on top of every sports target as though the adjustments were independently tested.[2][3]

A 2021 systematic review comparing animal and plant protein found no clear overall difference in absolute lean-mass change or strength, but some lean-mass analyses favoured animal protein, including in younger adults. Many comparisons involved supplements rather than complete dietary patterns. This supports neither “all proteins are identical in every situation” nor “plant protein cannot build muscle.”[5]

Most animal-protein comparisons used dairy, while most plant-protein comparisons used soy. Background diets were not always adequately described, and lean-mass results changed when individual studies were removed. Someone taking a plant supplement could still be eating animal foods. Do not turn that evidence into a precise ranking of every vegan diet against every mixed diet.[5]

Choose an approach that is affordable, acceptable and repeatable. Compare the whole diet, not just the amino-acid profile of an isolated scoop. A short-term rise in muscle protein synthesis is useful mechanistic evidence, but it is not itself a measurement of how much muscle someone gains over months.[3][5]

6. Timing without the stopwatch

You do not lose the benefits of a workout because a shake was not consumed immediately afterwards. A meta-analysis of protein timing found no clear independent strength or hypertrophy advantage after accounting for other factors; total daily protein explained much of the apparent benefit. Few studies tightly matched total protein, so this is not proof that timing never matters.[6]

A practical approach is to include protein-containing foods across meals rather than struggle to fit everything into one late serving. Sports guidance supports distribution through the day and flexibility around exercise. If you trained without eating beforehand and your next meal is far away, eating afterwards is sensible; it does not require a special branded recovery product.[3]

Start with sufficient daily intake and a sustainable meal pattern. Treat precise timing as a secondary question, not an emergency. Evidence about immediate laboratory responses should not be presented as proof of a narrow “anabolic window” after which all potential muscle gain disappears.[3][6]

7. Healthy kidneys versus kidney disease

A 2018 systematic review analysed 28 trials with 1358 participants without kidney disease. Higher-protein diets did not produce a worse change in glomerular filtration rate, or GFR, than lower- or normal-protein diets. GFR describes how quickly the kidneys filter blood. Comparing only end-of-study values showed higher filtration with higher protein, but that is not itself proof of kidney damage.[7]

This is reassuring within the populations, doses, durations and outcomes studied. It does not establish that any dose is harmless for a lifetime. The studies varied, some had unclear risk of bias, and a kidney-function marker is not the same as counting future kidney failure over decades. “Without kidney disease” also did not mean every participant was a healthy strength athlete.[7]

The review excluded people with indicators of kidney impairment, including protein in the urine or a history of kidney stones. Those exclusions matter: reassuring results cannot simply be extended to groups the researchers left out. Tell your clinician about a stone history or an abnormal urine test rather than assuming this review settles your situation.[7]

With existing chronic kidney disease, the decision is different. Protein metabolism generates waste that the kidneys must remove; some patients need moderated intake, while too little can cause malnutrition. Requirements can also change with treatment. Do not copy a gym target or put yourself on a low-protein diet: ask your kidney team or dietitian for an individual plan.[8]

For this dossier, there is no defensible universal upper limit that guarantees safety. Neither a sports target nor a reassuring short study establishes one. Extreme intakes and long-term use remain less certain. Known kidney disease, abnormal kidney tests or an existing medical diet are reasons to seek advice before increasing intake substantially.[2][7][8]

8. Digestion and allergy

A product can be unnecessary or poorly tolerated without being toxic to the kidneys. Milk-based shakes may contain lactose. In people with lactose intolerance, lactose can cause bloating, gas, abdominal pain or diarrhoea. Tolerance varies; the relevant issue is the product's ingredients and your response, not simply its protein claim.[9]

Lactose intolerance is not milk-protein allergy. Lactose is a sugar; allergy involves an immune response to milk proteins. A lactose-free label therefore does not make a whey or casein product appropriate for someone with milk allergy. Read ingredient and allergen information rather than assuming that a different formulation removes the problem.[3][9]

If a shake causes recurring symptoms, stop using it and review the ingredients and portion with a clinician or dietitian when needed. Do not interpret discomfort as evidence that it is “working”, or use a self-diagnosis of intolerance to ignore persistent symptoms. Replacing foods should also preserve an adequate overall diet.[9]

9. Supplement quality and testing

Research on protein as a nutrient does not certify every tub sold online. A product may contain additional ingredients, and contamination with prohibited substances is a separate concern, especially for tested athletes. The Dutch NZVT system lists tested product-and-batch combinations, not blanket approval of a brand.[10]

Independent testing can reduce uncertainty within the scope of the test. Check whether the exact product and batch appear in the relevant database. Do not assume a logo covers every batch, every possible contaminant or every health outcome. The Doping Authority explicitly states that even a listed product cannot guarantee avoiding a positive doping test.[10]

Prefer a clearly described product when a supplement genuinely fills a gap. Compare actual protein, ingredients and allergens rather than muscle-building slogans. Testing for banned substances is not proof of superior muscle growth, complete purity or suitability for kidney disease. This dossier recommends no brand and has not commissioned laboratory tests of products.[2][8][10]

10. A practical decision

Begin with the problem you are trying to solve. Is protein intake genuinely low, or are you expecting a supplement to compensate for an inconsistent training programme? Check a few representative eating days, including days without a workout. Then consider whether ordinary food or a convenient supplement best addresses any gap. The objective is adequate intake, not the maximum number of scoops.[3][11]

Seek personalised advice for kidney disease, food allergy, persistent digestive complaints, restrictive diets or difficulty eating enough. Frailty and disease-related weight loss need their own assessment. Children, pregnancy and breastfeeding have different nutritional contexts: the calculations and supplement discussion here are not instructions for those groups.[1][2][8][9]

11. Methods, access limits and sources

This is a focused evidence dossier, not a preregistered systematic review or personal treatment plan. Sources were checked on 2026-09-21. We prioritised official nutrition information and systematic reviews of training and kidney outcomes. Sports position statements provide practical context but are not equivalent to independent trials.

We distinguished total dietary intake from supplementation, additional gains from total training gains, and fat-free mass from muscle. We did not calculate a new pooled result. The numerical examples are arithmetic illustrations. Differences between studies, limited follow-up and indirect comparisons constrain certainty; studies pooled in several reviews are not necessarily independent evidence.

Access: the review articles below were available as full web text; relevant methods, results and limitations were consulted, not every underlying trial or supplement. EFSA's public summary was accessible, but its journal page and NIH ODS pages returned access errors. KDIGO's guideline PDF was reachable but not text-extracted, and its journal text was blocked; no unverified KDIGO numerical recommendation is used. Kidney-disease advice instead uses the accessible NIDDK page. No unavailable full text is represented as checked.

1. EFSA — protein reference intakes (2012). EFSA sets population reference intakes for protein. Official public summary checked: adult reference intake and mixed dietary sources. The underlying journal opinion was not accessible in this check.
2. Voedingscentrum — Eiwitten. Protein: functions, foods, requirements and special groups. Web text, including expanded-page HTML, checked. Supports food sources, vegan-diet considerations and caution against unlimited intake; public guidance, not a supplementation trial.
3. Jäger et al. — ISSN position stand (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Full web text available; position statement and relevant sections checked. Supports the sports range, food options and timing. Expert synthesis, not a systematic estimate of benefit; authors disclose supplement-industry relationships.
4. Morton et al. — resistance-training meta-analysis (2018). 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. Full main text checked, including absolute effects, intervention duration and uncertain breakpoint model. Individual trial reports and all supplementary files were not independently reanalysed.
5. Lim et al. — animal versus plant protein (2021). Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Full web text available; abstract and relevant interpretation checked. Outcomes and subgroups differ; not proof of identical effects for every plant source or whole diet.
6. Schoenfeld, Aragon and Krieger — protein timing (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Full web text available; abstract, methods and interpretation checked. Total intake confounds timing comparisons; older evidence, not proof that timing never matters.
7. Devries et al. — kidney-function meta-analysis (2018). Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis. Full text sections checked, including methods, results and discussion. Focuses on filtration measures in adults without kidney disease; not lifetime safety or treatment evidence for kidney patients.
8. NIDDK — nutrition in chronic kidney disease. Healthy Eating for Adults with Chronic Kidney Disease. Official web guidance checked, especially protein and individual dietary planning. Clinical needs differ; both excessive restriction and inappropriate increases can be problematic.
9. NIDDK — lactose intolerance. Definition & Facts for Lactose Intolerance. Official web text checked. Distinguishes lactose intolerance from milk allergy and explains variability in tolerance.
10. Doping Authority Netherlands — NZVT. Nederlands Zekerheidssysteem Voedingssupplementen Topsport. Official disclaimer checked: testing concerns specified product-batch combinations and prohibited substances; no guarantee against a positive doping test and no general health endorsement.
11. Voedingscentrum — strength training and nutrition. Eten en drinken bij spiergroei en krachtsport. Official web guidance checked for training adaptations and using ordinary foods to supply protein. Not an individual programme or a trial of a specific shake.