Three questions come up whenever someone trains hard and eats vegetarian : how much protein, from which sources, and whether the diet itself is good for long-term health. All three have been studied, with methods of different strength. This article separates what the trials show from what we derive from them, and names where the evidence ends.
How much protein
Three numbers from the studiesThe most cited figure comes from a meta-analysis of 49 randomised trials with resistance training : above about 1.6 grams of protein per kilogram of body weight per day, additional muscle mass barely increased. The confidence interval reaches up to 2.2 g/kg. Studies using the indicator amino acid method, which estimates the requirement more directly, land in the same range : about 1.65 g/kg after a 20 km run, 1.7 g/kg in bodybuilders on a rest day.
1.6 g/kg
A large meta-analysis with resistance training pointed to a plateau of additional lean mass at about 1.62 g/kg. Endurance athletes had a mean requirement of 1.65 g/kg after a 20 km run.
1.8 bis 2,0
Still within the confidence interval of the same meta-analysis. With resistance training, each further increase brought only small gains, without a clear plateau.
2.2 g/kg
Upper limit of the confidence interval around the estimated breakpoint. No added benefit above it has been shown : in a 16-week trial, 3.2 g/kg did no better than 1.6 g/kg. Not a safety limit.
Combined training does not change the picture much. In a 16-week trial with strength or concurrent strength and cycling training, 1.6 g/kg worked as well as 3.2 g/kg. One study after resistance training estimated 2.0 g/kg (1.62 to 2.38), in men who habitually ate 2.3 g/kg ; the authors themselves consider that value likely to be an overestimate. For people with healthy kidneys, a meta-analysis found no change in kidney function at higher intakes, on average up to about 1.8 g/kg ; long-term data above 2 g/kg are lacking.
Which sources
Soy keeps up, other plants lagProtein quality is measured today with the DIAAS score, which accounts for digestibility at the level of each essential amino acid. For muscle building, leucine also matters : it is the amino acid that triggers muscle protein synthesis. The amount of protein needed to supply about 2.7 grams of leucine shows how different the sources are.
| Source | DIAAS | Protein for 2.7 g leucine | In practice |
|---|---|---|---|
| Milk, milk protein | 123–141 | 31 g | Strong base ; low-fat versions |
| Whey | 125–133 | 25 g | Simplest portion after training |
| Egg | 135–137 | 39 g | Complete, but relevant for LDL |
| Soy (isolate, tofu) | 97–105 | 40 g | As effective as dairy protein in 17 trials |
| Pea | 60–73 | 38 g | Best in blends |
| Wheat / seitan | 54 / 28 | 45 g | Low in lysine ; combine with legumes or soy |
In muscle mass, the trials translate this as follows. A 2025 meta-analysis of randomised trials found no difference between soy and dairy protein across 17 trials (standardised mean difference −0.02), mostly soy isolate against casein or whey. Other plant proteins studied, namely rice, chia, oat and potato from five small trials, lagged behind (−0.58), and so did the subgroup with resistance training (−0.45), which pooled all plant sources ; whether the disadvantage under training also applies to soy, the analysis cannot say. In adults under 50, animal protein produced about 0.4 kg more lean mass in another meta-analysis. Blends can close the gap : a single serving of wheat, maize and pea stimulated muscle protein synthesis over five hours much like the same amount of milk protein ; this was not a training trial over weeks.
Our derivation from this, not a study result of its own : if at least half of the daily protein comes from dairy, whey, eggs or soy, there is no reason for a vegetarian surcharge. If most of it comes from legumes, grains and seitan, this derivation points rather to the upper end of the range the studies examined.
How much protein do vegetarians who train need?
In a large meta-analysis with resistance training, additional lean mass plateaued at around 1.6 g per kilogram of body weight per day, with an upper uncertainty limit of around 2.2 g/kg. A blanket surcharge for vegetarians is not shown, provided a good share of the protein comes from dairy, eggs or soy.
Is plant protein worse for building muscle?
Soy is not : in 17 randomised trials, soy showed no difference compared with dairy protein, mostly tested as protein powder. Other plant proteins studied (rice, chia, oat, potato ; five small trials) lagged behind on average. A blend of wheat, maize and pea stimulated muscle protein synthesis in the short term much like dairy protein.
Do vegetarians live longer?
It has not been shown. In two large cohorts, all-cause mortality in vegetarians was 0.91 and 1.00 compared with meat eaters, in neither case a firm difference. For heart health, quality matters : in the top versus bottom tenth of a healthful plant-diet index, coronary heart disease risk was 25 percent lower ; for the unhealthful index, 32 percent higher (Satija 2017). These are observational data, not proof of effect.
How much protein per meal makes sense?
A common rule of thumb from a review is at least 0.4 g/kg per meal across four meals, around 32 g at 80 kg. After whole-body resistance training, 40 g worked better than 20 g, and large portions are not wasted : 100 g had a longer effect than 25 g.
Which blood markers are informative for vegetarians?
For vitamin B12, the serum value alone does not reliably reflect functional status ; holotranscobalamin and methylmalonic acid can complement the picture, taking supplements and kidney function into account. Add ferritin with transferrin saturation, the omega-3 index and ApoB. What the values mean for you is something to discuss with your doctor.
One number from the largest British vegetarian study surprised us.
What the long-term data showAmount and source settle muscle building. The long-term data tell a second story. In the EPIC-Oxford cohort, vegetarians came out higher than meat eaters on one specific risk : in absolute terms about 3 more cases per 1,000 people over ten years, while the same study saw 10 fewer coronary events. Observational data, not proof. To our knowledge, none of the usual supplements, neither omega-3 nor creatine nor B12, has been tested in a study against this risk.
Which risk that is and how large it really is, what cheese, butter and eggs do to ApoB, why the usual serum B12 value can mislead under supplements, and which claim from a well-known podcast is too sweeping : that is the second part, along with the poster that puts the whole topic on one page.
All core numbers on one page
Protein amount, sources, quality and the blood values worth discussing, sharp and complete after signing in to the client area.
Sign in and view →The second part is for clients : the risk, ApoB, B12 and the poster.
Up to this point the article covers the mechanism. What follows moves from the mechanism to your own values, and that part we keep for the people we work with.
- Distribution over the day : portion size, the 40 gram question after training and why large portions are not wasted
- Which vegetarian diet is healthy : daily, sparingly, replace, with amounts from the cohorts and the effect of cheese, butter and eggs on ApoB and LDL
- What remains despite omega-3, creatine and B12 : haemorrhagic stroke, bone, iron, with absolute numbers rather than relative risks only
- Which blood values are informative for vegetarians and why serum B12 reveals little under supplementation
- Rhonda Patrick's FoundMyFitness take, sources checked (as of 4 October 2026), and the whole topic on one poster
There is no self-service sign-up. Access comes with working together ; the first conversation is free and non-binding.
Put it in context
How your diet, training and blood test results fit together is what I put in context in the Longevity Check-up. Whether and in what amount you take a supplement is a decision for you and your doctor.
Sources (studies and reviews)
- Morton RW et al. (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. Br J Sports Med 52(6):376-384. PMID 28698222.
- Kato H et al. (2016). Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method. PLoS One 11(6):e0157406. PMID 27322029.
- Bandegan A et al. (2017). Indicator Amino Acid-Derived Estimate of Dietary Protein Requirement for Male Bodybuilders on a Nontraining Day Is Several-Fold Greater than the Current Recommended Dietary Allowance. J Nutr 147(5):850-857. PMID 28179492.
- Tagawa R et al. (2021). Dose-response relationship between protein intake and muscle mass increase : a systematic review and meta-analysis of randomized controlled trials. Nutr Rev 79(1):66-75. PMID 33300582.
- Bagheri R et al. (2023). Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males. J Int Soc Sports Nutr 20(1):2236053. PMID 37516903.
- Mazzulla M et al. (2020). Protein Intake to Maximize Whole-Body Anabolism during Postexercise Recovery in Resistance-Trained Men with High Habitual Intakes is Severalfold Greater than the Current Recommended Dietary Allowance. J Nutr 150(3):505-511. PMID 31618421.
- Devries MC et al. (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. J Nutr 148(11):1760-1775. PMID 30383278.
- Mathai JK et al. (2017). Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than values calculated using the concept for protein digestibility-corrected amino acid scores (PDCAAS). Br J Nutr 117(4):490-499. PMID 28382889.
- Gorissen SHM et al. (2018). Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids 50(12):1685-1695. PMID 30167963.
- Reid-McCann RJ et al. (2025). Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia : A Systematic Review and Meta-analysis of Randomized Controlled Trials. Nutr Rev 83(7):e1581-e1603. PMID 39813010.
- Lim MT et al. (2021). Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength : A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients 13(2):661. PMID 33670701.
- Pinckaers PJM et al. (2022). The Muscle Protein Synthetic Response to the Ingestion of a Plant-Derived Protein Blend Does Not Differ from an Equivalent Amount of Milk Protein in Healthy Young Males. J Nutr 152(12):2734-2743. PMID 36170964.
- Ciuris C et al. (2019). A Comparison of Dietary Protein Digestibility, Based on DIAAS Scoring, in Vegetarian and Non-Vegetarian Athletes. Nutrients 11(12):3016. PMID 31835510.
- Satija A et al. (2017). Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults. J Am Coll Cardiol 70(4):411-422. PMID 28728684.
- Orlich MJ et al. (2013). Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med 173(13):1230-1238. PMID 23836264.
- Appleby PN et al. (2016). Mortality in vegetarians and comparable nonvegetarians in the United Kingdom. Am J Clin Nutr 103(1):218-230. PMID 26657045.
This article is educational and does not replace medical advice. StoaVita provides longevity and performance coaching, not medical treatment, gives no dosing recommendations for supplements and sells no supplements. Protein amounts are those used in the studies. Anyone with kidney disease or regular medication should discuss a high protein intake with their doctor first. Felix Baier is neither a physician nor a German-licensed Heilpraktiker.