Plant vs animal protein: can you build muscle without meat?

"You can't build muscle without meat." I have heard it a hundred times. Science says something else. A randomized trial from 2025 put young, active people either on a normal diet with meat or on a fully plant-based one. Then it measured how fast their muscle proteins were being built. The result: no difference.

Short answer: Yes, you can build muscle on plant protein the same way as on meat. The 2025 randomized trial found that plant and animal diets started muscle protein synthesis equally. What decides is how much protein you eat in total per day. Chicken or lentils is secondary. The study did look at young, healthy people over a short time.

What the study did

The researchers took 40 healthy, active people. For nine days they did strength training and ate a precisely set diet with 1.1 to 1.2 g of protein per kilo of body weight. One group ate animal sources, the other only plant sources. On top of that they tested whether the spread of protein across the day matters (evenly, or most of it in the evening meal). Then they measured muscle protein synthesis with a sensitive method.

The result: the source (almost) did not matter

Plant and animal diets started muscle protein synthesis the same.

The spread across the day did not play a big role either. Worries like "you must have 30 g in every meal" were unnecessary for these people.

Put simply: what decides is how much protein you eat in total per day, not whether it comes from chicken or from lentils.

Where the catch is (let's be fair)

I don't want to oversell this. These were young, healthy people, a short time and a fairly moderate protein intake. In older people, at a very high intake or in a hard deficit, small differences (protein quality, leucine content) can play a slightly bigger role. And above all: plant sources tend to have less protein and a less "complete" amino acid profile. That is easy to fix. You just have to think about it.

The practical minimum, so you build muscle from anything

• Watch your total intake: roughly 1.6 to 2.2 g of protein per kilo if you want to build or keep muscle. That is lever number one. More in how much protein you need.
• On a plant diet, add a bit on top and combine sources (legumes plus grains, tofu, tempeh, soy, a good plant protein powder). That evens out the amino acid profile.
• Don't stress about timing. Spread protein over roughly 3 to 5 meals and you are done. Forget precision to the minute. More on that in protein timing after a workout.

What to take from this

Muscle does not stand on meat. It stands on enough protein and on training. If you eat plant-based, there is no reason to fear that "it won't work". Just watch the total amount and combine sources. And if you eat meat, that is fine too. The best diet is the one you can stick to and that gives you enough protein.

Frequently asked questions

How did the researchers compare plant and animal protein?

They took 40 healthy, active people who did strength training for nine days and ate a precisely set diet with 1.1 to 1.2 g of protein per kilo of body weight. One group ate animal sources, the other only plant sources. Then muscle protein synthesis was measured with a sensitive method.

Does it matter how I spread protein across the day?

For the people in the study the spread across the day did not play a big role, and worries like "you must have 30 g in every meal" were unnecessary. In practice it is enough to spread protein over roughly 3 to 5 meals and not chase precision to the minute.

How much protein should I eat to build muscle on a plant diet?

Roughly 1.6 to 2.2 g of protein per kilo if you want to build or keep muscle. On a plant diet add a bit on top and combine sources, for example legumes with grains, tofu, tempeh, soy or a good plant protein powder. If you have health problems or follow a special diet, talk to your doctor.

Does this apply to older people or a hard diet?

The study looked at young, healthy people, a short time and a fairly moderate protein intake. In older people, at a very high intake or in a hard deficit, small differences such as protein quality and leucine content can play a slightly bigger role.

Sources, so you can check:

1) Askow A. et al., "Impact of Vegan Diets on Resistance Exercise-Mediated Myofibrillar Protein Synthesis in Healthy Young Males and Females: A Randomized Controlled Trial", Med Sci Sports Exerc, 2025. DOI: 10.1249/MSS.0000000000003725

Martin Barna

Online nutrition and fitness coach. Since 2013 I have helped 600+ people lose fat and keep the result. Science, not crash diets.

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This article is for information only. It is not medical advice. If you have a health condition, talk to your doctor.