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 clear difference.

Short answer: Very likely yes. In a 2025 randomized trial, a fully plant-based diet supported muscle protein synthesis just as well as a diet with meat. Both groups ate the same amount of protein, so the source did not seem to matter. Other research shows that your total daily protein intake has the biggest effect. The study measured muscle building over nine days, not muscle gain over months, and it looked at young, healthy people.

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 a mixed diet that included meat, the other a fully vegan diet. 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: no clear difference between plant and animal protein

Plant and animal diets showed no clear difference in muscle protein synthesis.

Whether protein was spread evenly or mostly eaten in the evening made no clear difference to muscle protein synthesis in these people either.

Put simply: at the same total intake, it did not matter whether protein came 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: many plant foods have less protein per serving and less leucine and lysine than meat (soy is an exception). 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. The study itself used less (1.1 to 1.2 g/kg), so this range is from broader research. If you have kidney problems or another health condition, check with your doctor first. More in how much protein you need.
• On a plant diet, aim for the upper half of that range and combine sources (legumes plus grains, soy foods like tofu and tempeh, a good plant protein powder). That evens out the amino acid profile.
• Spreading protein over roughly 3 to 5 meals is plenty. There is no need to time it to the minute. More on that in protein timing after a workout.

What to take from this

Muscle is built by enough protein and training, whatever the source. 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. For most of my clients, the diet that works is the one they can stick to and that gets them 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 a mixed diet that included meat, the other a fully vegan diet. Then muscle protein synthesis was measured with a sensitive method.

Does it matter how I spread protein across the day?

Whether protein was spread evenly or mostly eaten in the evening made no clear difference to muscle protein synthesis in the study. 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 aim for the upper half of that range and combine sources, for example legumes with grains, soy foods like tofu and tempeh, or a good plant protein powder. If you have kidney problems or another health condition, or follow a special diet, talk to your doctor first.

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 coached 600+ clients through fat loss and keeping the weight off. 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.