Strength
You don’t have to harm animals to be strong
No gapMuscle built on plants vs animal protein in these trials
When protein is matched, vegan and omnivorous diets build the same muscle — trials that biopsy muscle, scan it with DXA and MRI, and test 1-rep max keep finding that. Illinois used isotope tracers after lifting: no difference in muscle-protein synthesis. A Brazilian trial followed men who had already been vegan for at least a year for 12 weeks of supervised lifting: lean mass, ultrasound, biopsies, and strength all moved the same as omnivores. A UK trial lifted five days a week for 10 weeks — lean mass rose 2.6 kg on the omnivorous diet and 3.1 kg on vegan; thigh muscle volume rose 8.3% in both; fiber area rose about a third in both. Older adults build muscle protein on a vegan menu at the same rate. Pea protein grew biceps about 20% versus about 16% on whey. We do not have to harm animals to be strong.
What the evidence says
The main points first. Every claim is tied to a source below.
Illinois: same muscle-building rate on a vegan plate
Nicholas Burd and Andrew Askow randomized 40 young adults to a vegan diet or an omnivorous diet for nine days of lifting, after a week getting used to the menu. Protein was a moderate 1.1–1.2 g per kilogram — closer to what people actually eat than the mega-doses in supplement ads. They drank deuterium-labeled water so newly built muscle protein could be traced, and they took leg-muscle biopsies at the start and end. Muscle-protein synthesis did not differ. Spreading protein evenly across meals did not matter either. Earlier one-meal studies had favored animal protein. A whole diet, with training, did not.
Habitual vegans gained the same lean mass in 12 weeks
Hevia-Larraín and colleagues in Brazil compared 19 men who had been vegan for at least a year with 19 omnivores. Protein was matched at 1.6 g/kg. Both groups did supervised lifting twice a week for 12 weeks. DXA scans of leg lean mass, ultrasound, biopsies, and 1-rep-max tests all moved the same way. These were not people trying tofu for a weekend. The vegan group had already been eating plants. They still packed on muscle like the meat-eaters.
Ten weeks, five days a week: same size, same strength
Monteyne’s team first used stable isotopes to measure daily muscle-protein synthesis on a high-protein vegan diet (mycoprotein) versus an omnivorous diet at about 1.8 g/kg. Rates matched at rest and after exercise. Then 22 young adults lifted five times a week for 10 weeks at about 2 g/kg. Lean mass rose 2.6 kg on the omnivorous diet and 3.1 kg on vegan. Thigh muscle volume rose 8.3% in both. Muscle-fiber area rose about a third in both. Strength on multiple lifts rose to comparable degrees. DXA, MRI, biopsies, and 1RM — not a bathroom scale.
Older adults: vegan diets did not slow muscle-protein synthesis
Monteyne 2020 found a mycoprotein vegan diet supported the same daily muscle-protein synthesis as an omnivorous diet in older adults. Domić 2024 used a 10-day integrated tracer method in active older men and women at about 1.2 g/kg: a well-balanced vegan menu did not compromise mixed-muscle protein synthesis versus an isocaloric, protein-matched omnivorous diet. Aging muscle still builds on plants when the protein is there.
Pea protein built as much arm muscle as whey
Babault and colleagues randomized 161 young men to pea protein, whey, or placebo during 12 weeks of resistance training. Biceps thickness rose 20.2% on pea and 15.6% on whey — not a win for dairy. Strength rose about 17% on both proteins. Lim’s 2021 review of plant versus animal protein for lean mass and strength found that once protein is matched, the gap that older acute studies advertised mostly disappears.
Sources
Papers and datasets. Caveats stay on the card — small samples and single animals included on purpose.
University of Illinois / MSSE, 2025 · Clinical
Illinois RCT — vegan vs omnivorous diet after lifting
Askow, Burd and colleagues: 40 young adults, randomized, nine days of training after a week on the assigned diet. Protein 1.1–1.2 g/kg. Deuterium-labeled water plus leg-muscle biopsies tracked myofibrillar protein synthesis. No difference between vegan and omnivorous diets. Meal-to-meal protein distribution did not matter either. A whole diet beat the old one-meal dogma.
Sports Medicine, 2021 · Clinical
Habitual vegans vs omnivores — 12 weeks of lifting
Hevia-Larraín et al.: 19 men vegan for at least a year vs 19 omnivores, protein matched at 1.6 g/kg, supervised resistance training twice a week for 12 weeks. Leg lean mass (DXA), ultrasound, biopsies, and 1RM all increased similarly. Protein source was not the limiter.
Journal of Nutrition, 2023 · Clinical
Mycoprotein vegan diet — 10 weeks, five sessions a week
Monteyne et al.: daily muscle-protein synthesis matched on high-protein vegan vs omnivorous diets (~1.8 g/kg). Then 10 weeks of high-volume lifting at ~2 g/kg: lean mass +2.6 kg omnivorous vs +3.1 kg vegan; thigh volume +8.3% both; fiber area about +33% vs +32%. Strength rose to comparable degrees. DXA, MRI, biopsies, 1RM.
British Journal of Nutrition, 2020 · Clinical
Older adults — mycoprotein vegan diet, same synthesis rates
Monteyne 2020: a mycoprotein-based high-protein vegan diet supported equivalent daily myofibrillar protein synthesis compared with an isonitrogenous omnivorous diet in older adults. Randomized.
Journal of Nutrition, 2024 · Clinical
Active older adults — 10-day vegan menu, same mixed-muscle synthesis
Domić et al.: physically active older men and women, vegan vs omnivorous diets at about 1.2 g protein/kg, isocaloric and isonitrogenous. Ten-day integrated muscle-protein synthesis did not differ. A carefully composed vegan diet did not compromise the anabolic response.
Journal of the International Society of Sports Nutrition, 2015 · Clinical
Pea protein vs whey — 161 men, 12 weeks
Babault et al.: pea protein, whey, or placebo during resistance training. Biceps thickness +20.2% pea vs +15.6% whey vs +8.6% placebo. Strength rose about 17% on both proteins. Pea was not a consolation prize.
Nutrients, 2021 · Review
Plant vs animal protein for lean mass — review
Lim et al.: once total protein is matched, plant proteins support lean-mass and strength gains comparably to animal proteins in resistance-training studies. Older acute meal tests that favored milk or meat do not decide a whole diet.