When people mention “muscle foods,” the first thing that comes to mind probably isn’t lentils.

That thinking is only partially based on science.

Here’s what folks tend to get right: Meat, poultry, eggs, fish, and dairy all offer the full range of essential amino acids, whereas most plant foods do not.

Mind you, plants aren’t deficient in essential amino acids (EAAs). It’s just that most plant foods contain smaller amounts of EAAs and tend to be especially low in lysine, methionine, threonine, and tryptophan. These differences in amino acid profiles have led some to describe animal protein as “higher quality” than plant protein. (1)

However, people on fully plant-based diets can and do build muscle.

More importantly, in recent years, research has shown that plant protein can support muscle growth as effectively as animal protein, including the study you’ll be reading about today. (2)

Conducted by researchers at the University of Helsinki, University of Alberta, American College of Lifestyle Medicine, and the University of New England, the study adds to a growing body of evidence supporting the use of plant-based proteins to support muscle gains.

What the study found

Researchers set out to answer a common question:

Can an entirely plant-based eater consume enough protein and vital amino acids—especially leucine, which is critical for muscle protein synthesis—from plants to support bodybuilder-level muscle growth?

To determine the answer, the researchers used preexisting findings and recommendations to calculate a typical competitive bodybuilder's energy, protein, and leucine needs. That came to more than 4,200 daily calories spread out over four meals, 135 grams of protein, and 8 grams of leucine.

The researchers then used data from the Adventist Health Study-2. This data set included the dietary records of 71,751 people, 5,694 of whom followed an entirely plant-based diet. Those food records allowed the researchers to estimate the protein and leucine intakes of this group of entirely plant-based eaters.

Once the researchers determined those numbers, they scaled them up to match the caloric intake of a typical competitive bodybuilder. When they did, their analysis revealed that the entirely plant-based Adventists would theoretically consume enough leucine and protein to build muscle, provided they also consumed enough calories, as the chart below shows.

The researchers concluded that completely plant-based diets scaled to meet the caloric demands of adult male bodybuilders can, indeed, “surpass the protein and leucine intakes required for optimal muscle development as recommended in existing literature, as well as most other micronutrient intake levels.”

Takeaways

This study is theoretical—and not based on real bodybuilders eating plant-based meals.

That matters—because it’s easy to argue with many of the assumptions made by the researchers.

For one, The 4200-calorie benchmark was higher than a typical bodybuilder would consume.

In addition, the protein benchmark was lower than what many bodybuilders shoot for.

As a result, it’s difficult to make any conclusions based on this study alone.

That said, some fully plant-based bodybuilders have found a way to consume enough protein to support muscle growth. Plus, other research supports the study’s conclusion—consuming enough plant protein to support muscle growth is possible.1

Possible, however, isn’t synonymous with easy.

Building muscle while consuming only plant protein takes more effort, planning, and education.

It also generally requires supplementing with a plant-based protein powder to help boost overall protein without consuming an enormous amount of calories or fiber that typically comes “packaged” with whole food (which brings us to our next point).

The scaled-up plant-based bodybuilding diet includes a whopping 99 grams of fiber.

As the researchers noted, when you scale up a minimally processed, plant-based diet to meet the caloric and protein needs used in the study, you’re scaling up all dietary nutrients—including fiber.

The result: The scaled-up plant-based bodybuilding diet includes 99 grams of fiber daily—much more than the typical human would comfortably consume and digest.

Seventh-day Adventists eat differently than most people.

The Seventh-day Adventists are a Protestant church with members primarily based in Loma Linda, California. This city is considered one of the world’s “Blue Zones,” a region where people live longer than average.

In addition to typical evangelical Christian beliefs, Seventh-day Adventists also emphasize nutrition and overall health.

Many Seventh-day Adventists abide by the Kosher restrictions from the Old Testament. They fill their plates with fruits, vegetables, whole grains, legumes, and healthy fats like olive oil. They also minimize processed foods, sugar and its substitutes, and food additives.

What we described above is the opposite of the so-called “Oreo vegan” diet.

In other words, a fully plant-based eater can consume enough protein and leucine to support muscle growth if they eat like a Seventh-day Adventist.

However, not all fully plant-based eaters do so. If you get most of your calories from processed “vegan” snack foods and pasta, you’ll likely struggle to reach the protein and leucine goals from the study.

Planting seeds of change,

Michael Beiter

Certified Personal Trainer

PN L1 Sleep, Stress Management, and Recovery Coach

References

1. Nichele S, Phillips SM, Boaventura BCB. Plant-based food patterns to stimulate muscle protein synthesis and support muscle mass in humans: a narrative review. Appl Physiol Nutr Metab. 2022 Jul 1;47(7):700–10.

2. Goldman DM, Warbeck CB, Karlsen MC. Completely Plant-Based Diets That Meet Energy Requirements for Resistance Training Can Supply Enough Protein and Leucine to Maximize Hypertrophy and Strength in Male Bodybuilders: A Modeling Study. Nutrients [Internet]. 2024 Apr 10;16(8).

3. Messina M, Lynch H, Dickinson JM, Reed KE. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. Int J Sport Nutr Exerc Metab. 2018 Nov 1;28(6):674–85.

4. Hamilton-Reeves JM, Vazquez G, Duval SJ, Phipps WR, Kurzer MS, Messina MJ. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril. 2010 Aug;94(3):997–1007.