Let’s talk about plant-based diets and protein consumption.

Choosing a plant-based diet comes with many pressing questions, especially if you’re a dedicated fitness buff trying to maximize your nutrition intake: Am I getting enough protein by only eating plant-based foods? Are all proteins the same? And what type of protein is best for muscle growth?

The good news is that plant protein does build muscle, although it comes with a few more considerations than if you were consuming animal protein.

A quick refresher on protein

First, let’s do a quick overview of what protein is, and how it works.

Proteins are large molecules that are made up of smaller components known as amino acids. Your body actually synthesizes several of these amino acids on its own, but there are 9 that your body can’t easily make:

1. Histidine 
2. Isoleucine
3. Leucine
4. Lysine
5. Methionine
6. Phenylalanine
7. Threonine
8. Tryptophan
9. Valine 

These 9 amino acids are called essential amino acids (EAAs for short) and you need to get them from your diet in order to allow your body to make complete protein molecules.

As just about any athlete or casual gymgoer will tell you, protein is important because it acts as the “building blocks” for all of your body’s tissues, muscles included. When you’re following a good exercise routine that includes resistance training (aka lifting weights), it provides a stimulus for growth. Your body then responds to that stimulus by creating new muscle tissue. This response requires muscle protein synthesis to happen and, more precisely, it requires certain amino acids, including leucine [1] to start the reaction.

When your diet has enough leucine and other essential amino acids, your body can properly respond to your lifting stimulus, and build thicker, stronger muscle fibers.

So, the million-dollar question here is: are all proteins the same? No, not really, and it really starts to show when you look at the differences between plant protein vs animal protein.

Plant protein vs. animal protein

Obviously, the easiest difference you can distinguish between plant vs. animal proteins is their source. Animal protein can come from a wide variety of animal and animal by-products including meat, poultry, whey, and other dairies. Meanwhile, plant-based protein can come from a wide variety of plant foods, some of the most notable of which are legumes, wheat, grains, and oats.

Animal-based food sources generally tend to have more protein than plant-based sources per weight. But even more important is the difference in quality between plant vs. animal proteins.

What this means:

• Most animal-based proteins are complete protein sources, so they contain sufficient amounts of all 9 essential amino acids that your body can’t make on its own.
• Most plant-based proteins are incomplete, so they won’t have all 9 amino acids in the optimum amounts that you would need for muscle growth.

In addition to the different amino acid profiles in animal protein vs. plant protein, it’s also important to note that some plant proteins tend to be of lower quality than animal proteins. Protein quality is evaluated using the PDCAAS (Protein Digestibility Corrected Amino Acid Score), which takes into account both the amino acid profile of a protein source and your body’s ability to digest it (in other words, its bioavailability). Because some plant-based protein sources contain antinutritional factors [2], which are other components in the food that interfere with nutrient absorption, this can negatively impact the amount of protein that your body can actually use. This means that plant proteins tend to rank lower for their PDCAAS score than animal proteins. 

Plant protein vs. animal protein for building muscle

Due to its higher quality, the fitness world definitely has a bias towards animal-based proteins for muscle growth. Moreover, the research around this subjectalso seems to suggest that animal-based proteins are better than plant-based sources when comparing similar total protein consumption. 

For example, a 2021 meta-analysis [3] of 18 different studies concluded that animal protein tended to be more beneficial for lean muscle mass gains than plant protein in younger adults under the age of 50.

Let’s take a closer look at why this might happen.

In equal amounts (gram for gram), animal protein is going to be the best for building muscle because it has higher amounts of leucine. As we’ve already discussed, the amino acid leucine is the primary amino acid responsible for stimulating muscle protein synthesis.

So when we compare plant protein vs. animal protein, animal proteins are obviously going to have the upper hand since they by definition are complete proteins that include ample amounts of leucine, while most individual plant proteins aren’t going to compare. [4]

Now, with all that said, it isn’t that plant protein isn’t good for building muscle. There’s just a lot more to consider when sticking to a plant-based diet.

Does Plant Protein Build Muscle? 

A 2020 study [5] highlighted this by comparing soy and whey protein supplements that were matched to have the same amount of leucine by increasing the total amount of soy supplement consumed by the soy group. A group of 61 adults was randomly assigned to have one of the two protein supplements, each of which contained 2 grams of leucine. They also participated in a resistance training program three times a week for the 12-week trial.

What the researchers found: there was no significant difference in the amount of total muscle mass gained when the two groups were compared.

So the key takeaway here is that even plant protein can support your muscle growth as long as you’re getting the right amounts, both of total protein and the amino acid leucine. You may have to eat a higher volume of protein from plant-based sources than you would if you were eating meat and other animal-based foods, but the good news is that it can be done.

There’s also an easy workaround that lets you get all of the essential amino acids you need from plant-based foods: simply eat a more diverse array of plant foods containing protein! [6]

Even though individual plant foods may not contain optimum amounts of each essential amino acid when consumed alone, you can meet your requirements by eatingcomplementary proteins that fill in the gaps for what the other protein source lacksRice and peas [7] are great examples of complementary protein sources since they can address most of your essential amino acid needs when eaten together, even if they can’t make up your needs individually.

Bottom line: is plant protein as good as animal protein?

All things equal, plant protein can be just as good as animal protein for building muscle. But when we say “all things equal,” we aren’t just talking about the grams of protein in each; we’re also looking more closely at the quality of the amino acids that are present. Even though plant proteins tend to be of lower quality than animal proteins, you can absolutely get enough protein for muscle growth from plant proteins as long as you’re eating sufficient total protein from different sources.

So how can you make sure that your plant-based diet is giving you all the tools you need to grow?

• Eat a wide range of plant-based foods to get all of the amino acids you need.
• In addition to reaching your minimum total protein goal, pay extra-close attention to the amount of leucine you’re getting. This generally means you’ll need to eat more total grams of protein than the amount you would need from animal-based proteins (somewhere around 0.7 to 0.8 grams per pound of body weight [8] at least).

To sum it up, here’s the good news for all you plant-based eaters out there: as long as you’re approaching it the right way, there’s nothing to suggest that being vegan or vegetarian is going to get in the way of your muscle gains!

 

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References

1. Blomstrand, Eva et al. “Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise.” The Journal of nutrition vol. 136,1 Suppl (2006): 269S-73S. doi:10.1093/jn/136.1.269S

2. Sarwar Gilani, G et al. “Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality.” The British journal of nutrition vol. 108 Suppl 2 (2012): S315-32. doi:10.1017/S0007114512002371

3. Lim, Meng Thiam et al. “Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Nutrients vol. 13,2 661. 18 Feb. 2021, doi:10.3390/nu13020661

4. van Vliet, Stephan et al. “The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption.” The Journal of nutrition vol. 145,9 (2015): 1981-91. doi:10.3945/jn.114.204305

5. Lynch, Heidi M et al. “No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial.” International journal of environmental research and public health vol. 17,11 3871. 29 May. 2020, doi:10.3390/ijerph17113871

6. Berrazaga, Insaf et al. “The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review.” Nutrients vol. 11,8 1825. 7 Aug. 2019, doi:10.3390/nu11081825

7. Hertzler, Steven R et al. “Plant Proteins: Assessing Their Nutritional Quality and Effects on Health and Physical Function.” Nutrients vol. 12,12 3704. 30 Nov. 2020, doi:10.3390/nu12123704

8. Stuart M. Phillips & Luc J.C. Van Loon (2011) Dietary protein for athletes: From requirements to optimum adaptation, Journal of Sports Sciences, 29:sup1, S29-S38, DOI: 10.1080/02640414.2011.619204