Plant-based diets are often associated with sustainability, ethics, and health benefits. But what about plant-based proteins and muscle growth? Can they rival animal proteins, or are they perhaps even better? An update.

WHY DO YOU NEED PROTEIN AT ALL?

Proteins are essential for muscle growth. When you ingest proteins, they are digested into smaller blocks called amino acids. Chains of these amino acids are absorbed from the intestines into the bloodstream. Your body breaks down these chains into individual amino acids, which in turn serve as building blocks for the protein in your body cells. Compare it to a child taking apart a LEGO creation and building something else with the same bricks.

In the case of muscle tissue, we also speak of muscle protein synthesis, briefly summarized as the process of building proteins in muscle cells. Muscle protein synthesis does not necessarily mean that a muscle grows. That only happens when muscle protein synthesis exceeds muscle breakdown (as a result of overload in training). In that case, we also speak of a positive muscle protein balance.

HOW MUCH PROTEIN DO YOU NEED FOR MUSCLE GROWTH?

To build maximum muscle, you need approximately 1.6 to 2 grams of protein per kilogram of body weight daily, as has been convincingly established by science. That is twice as much protein as a non-bodybuilder needs.

Additionally, it has been shown that it is best to distribute your protein intake evenly throughout the day in ‘shots’ (meals) of 20-40 grams. This is likely the best way to stimulate muscle protein synthesis. In practice, this means consuming four to five protein-rich meals a day, with three to four hours between each.

It is therefore clear that the amount of protein plays an important role in muscle building. But what about the quality of proteins? Are all types of protein equally effective for muscle building?

RESEARCH: ANIMAL VERSUS PLANT PROTEINS

Researcher Jorn Trommelen concludes, based on scientific literature, that animal proteins are slightly better than plant proteins for muscle growth. It is explicitly noted that in most studies, animal and plant proteins perform equally, with a smaller number of studies favoring animal proteins. There are no known studies in which plant proteins are the winner. This, once again, applies to muscle building. See also a scientific review by Trommelen and his colleagues.

The perceived benefit of animal proteins may be related to the lower leucine content typically found in plant proteins. Leucine is the most important amino acid for muscle growth. More on that later.

META-ANALYSIS 4-2025

A meta-analysis of 12 studies concluded that animal proteins stimulate more muscle protein synthesis on average than plant proteins. The difference was small, but the average was negatively influenced by one study in which the plant group consumed more total protein (to compensate for the leucine content). This was the only study that favored plant proteins and had the second-largest effect size. In studies with equal protein supplementation, 10 of the 11 effect sizes favored animal proteins.

The benefit of animal proteins was also greater in the elderly. The elderly may have anabolic resistance, requiring a higher amount of protein per meal, particularly leucine, to significantly increase muscle protein synthesis.

META-ANALYSIS 7-2025

A meta-analysis of 30 studies compared animal and plant protein sources that were equal in total protein and calorie intake. Animal sources resulted in significantly more muscle mass and lower body strength, but there were no significant differences between the proteins regarding upper body strength or athletic performance. However, the superiority of animal proteins was not great.

Coach and researcher Menno Henselmans says about this:

In general, animal protein sources appear to be more effective than plant-based sources, but the difference in practice is nowhere near as large as researchers (myself included) had theoretically expected.

META-ANALYSIS 4-2026

A meta-analysis of 12 studies, including muscle growth expert Brad Schoenfeld, shows that animal proteins offer a modest advantage in stimulating muscle protein synthesis compared to plant proteins. However, the observed benefit of animal proteins was largely limited to older adults (over 65), whereas younger individuals showed similar responses regardless of the protein source.

In older adults, anabolic resistance appears to increase the leucine threshold, meaning that a higher leucine intake per meal is required to effectively stimulate muscle protein synthesis.

Schoenfeld concludes:

In combination with recent longitudinal studies, the evidence suggests that both plant-based and animal proteins can support similar muscle adaptations, provided that total daily protein intake is sufficient (approximately 1.6 g/kg).

THE DOWN SIDES OF PLANT-BASED PROTEINS

Why do plant-based proteins turn out somewhat unfavorably for muscle growth on balance? Trommelen identifies three points.

1. LOWER CONTENT OF ESSENTUAL AMINO ACIDS

There are a total of 22 amino acids. The body can produce 13 of them itself. You obtain the remaining 9 from your diet. These are called essential amino acids. In terms of protein content, animal proteins have a higher content of essential amino acids than plant proteins. As mentioned, this also applies to the important amino acid leucine.

2. DEFICIENT COMPOSITION OF ESSENTIAL AMINO ACIDS

But it is not only the total number of amino acids that matters; the composition of those amino acids also matters: the amino acid profile. Compare it to building a house: if you have bricks and windows but no doors, you cannot build a well-functioning house. The same applies to building muscle proteins: you need sufficient amounts of all individual essential amino acids. If a protein source is low in one of the essential amino acids, you are missing an ingredient for muscle protein synthesis. Many plant-based proteins are low in one or more essential amino acids.

3. LOWER DIGESTIBILITY

Digestibility is how well protein can be broken down into amino acids. Those amino acids are subsequently absorbed (taken up by the intestines) and ultimately transported to tissues such as muscles. So, a digestibility of 80% would mean that 20% of the protein is not digested and is excreted in the stool. That protein has not had the opportunity to do something useful in the body, such as building muscle.

Plant-based proteins generally have lower digestibility than animal proteins. This is because plant-based foods often contain so-called antinutrients, which serve to protect the plant but contain no nutrients.

In short, from a muscle growth perspective, plant-based proteins have several characteristics that make them inferior to animal proteins. But again, meta-analyses show that the difference is much smaller than was or is often thought.

SOLUTIONS FOR PLAT-BASED PROTEINS

Do you eat a plant-based diet and want to play it safe? Try one or more of the following solutions to compensate for the theoretical shortcomings of plant-based proteins. They are especially useful for older strength athletes.

1. EAT MORE PROTEIN

The first solution is simply to eat more protein. For vegetarians, and certainly for vegans, it is true that you need to eat more protein than the standard recommendation of 1.6 g per kg of body weight per day. As a vegetarian, aim for a protein intake of around 2 g/kg/d, and as a vegan, 2.2 g/kg/d. By doing so, you compensate for the lower content of essential amino acids, the less favorable composition of those essential amino acids, and the lower digestibility.

Getting even more protein is easier said than done. On average, protein density is much lower in plant-based products than in animal products. Getting 20 grams of protein from a steak is easy, but just try getting it from potatoes. Additionally, you will need many extra calories. So, as far as we are concerned, eating more protein ‘just like that’ is not ideal.

2. TAKING PROTEIN SUPPLEMENTS

Plant-based protein supplements are an easy way to increase your protein intake without unwanted calories from carbohydrates, and without filling you up as much as whole foods.

In addition, plant-based protein supplements have high digestibility, which solves the third problem with plant-based proteins as well.

3. ADD MISSING AMINO ACIDS

Another solution is to fortify foods with a low content of a specific amino acid. For example, there are many meat substitutes available, and many of these products are fortified with lysine and methionine, two amino acids that are often lacking in plant-based proteins.

4. STRAREGICALLY MIXING PROTEIN SOURCES

A fourth solution is the strategic mixing of two or more protein sources. If a protein is high in lysine and low in methionine, it is the perfect partner for another protein that is high in methionine and low in lysine. For example: peas combined with brown rice.

That sounds logical, but it does mean that you need to be well-informed about the nutritional values ​​of products.

CONCLUSION

Animal proteins are far less beneficial for muscle growth than is often still thought. Scientific meta-analyses show that actually only older adults (65+) benefit from animal proteins. For young gym-goers, the difference appears to be negligible.

It should be noted, however, that the quality of plant-based proteins regarding muscle growth is theoretically slightly lower than that of animal proteins. Therefore, if you consume exclusively plant-based protein, you may want to supplement your diet with plant-based protein supplements. These provide you with plenty of plant-based protein, including essential amino acids, and offer high digestibility, without consuming too many calories. However, you can also obtain a lot of plant-based protein from regular food. Legumes, in particular, are a protein-rich and healthy food source. Another recommendation is pea protein, which does contain a complete amino acid profile.