Can you build muscle on a vegan diet?

The best-controlled study had habitual vegans and omnivores strength-train for twelve weeks with matched protein intake, around 1.6 grams per kilo of body weight per day. Muscle growth and strength gains were comparable between the groups, and the authors concluded that protein source does not affect resistance-training adaptations as long as protein intake is adequate (Hevia-Larraín 2021).

A systematic review and meta-analysis of 16 randomised trials paints a more nuanced picture. Overall, neither muscle strength nor absolute lean mass differed between animal and plant protein. In younger adults under 50, however, there was a small advantage for animal protein on lean mass (Lim 2021). The difference is small and confined to a subgroup, not a barrier to building muscle on a vegan diet.

Why does that small gap appear? Plant protein is digested slightly less well and generally contains less leucine, the amino acid that most strongly switches on muscle protein synthesis. A critical review notes that this can be offset: eat a little more total protein, vary the plant sources so the amino acid profile is complete, and get enough leucine per meal (Berrazaga 2019).

Taken together, building muscle on a vegan diet is well established. What decides it is the same as for omnivores, enough total protein and progressive strength training. The vegan just has to be a bit more deliberate about amount and variety.

The idea that muscle requires meat is old and emotionally charged. Meat and strength have long been linked culturally, and in gym settings the way people talk reinforces it. There is also a simple illusion at work: many large, muscular people eat a lot of meat, so the brain reads it as cause and effect when it is really a habit. Then there are the incentives. The meat and dairy industries, along with much of the protein-powder and supplement business, profit from the message that animal protein is superior. 'Complete protein' sells. The small, subgroup-specific edge the research shows is easily inflated into an absolute rule, because an absolute rule is easier to market than an 'it depends on the amount'.

If you strength-train and eat vegan: aim for enough total protein, around 1.6 grams per kilo of body weight per day, and spread it across the day. Combine different plant sources such as legumes, grains, soy, tofu and tempeh so the amino acid profile is complete. Soy and pea protein come closest to animal protein in profile. Calculate your own protein needs before you guess.