Protein is essential when you’re building muscle. Muscle tissue is made of protein, which means it is made of amino acids, and those amino acids have to come from somewhere. But how much does the source of protein matter?
Animal foods (like meat, dairy, and eggs) contain lots of protein, so they’re the traditional go-to foods for bodybuilders and other gym-goers. But plant foods can provide protein as well, and there are plenty of strong vegan athletes—so it’s definitely possible to build muscle on a plant-based diet.
There are two downsides of plant-based protein, so if you’re determined to stick to these sources, it’s important to account for both.
Plant foods generally have more calories for the same amount of protein
If you’re watching your overall calories (for example if you are trying to lose weight, or maintain your weight in a specific range), meat is a more efficient way to get protein in. A small chicken breast, for example, has 27 grams of protein in just 142 calories. Nearly all of the calories come from protein, a few from fat, and none from carbs.
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No whole food plant source can match those macros. Three-quarters of a cup of tofu will give you roughly the same calories, but with only 15 grams of protein. (The rest is carbohydrate and fat.) Or try 100 grams of rice and beans: 150 calories, but only 5 grams of protein. (The rest is mostly carbs.)
So if you want to build muscle on plant foods, you’ll have to work a little harder than an omnivore to get all your protein in without going over your calorie target. You’re more likely to need protein powder to make up the difference, where an omnivore could more easily meet their needs with a few meat-containing meals.
You may need more plant protein than animal protein to get all your amino acids
When we say we need protein in our diet, what we really mean is that we need amino acids. There are 20 amino acids, nine of which we cannot make in our bodies and need to get in our diet.
Animal foods, conveniently, have a balanced selection of amino acids—if you eat meat as your main protein source, you’ll get plenty of all the amino acids you need. But plant foods aren’t always as well balanced. This is why plant proteins are sometimes referred to as lower “quality” protein. There’s nothing wrong with the protein itself; quality just refers to the amino acid balance. (Another term for having all the essential amino acids is “complete” protein.)
A plant-based diet will still provide all the amino acids, if you have a reasonable variety of foods. Rice and beans famously balance each other out, for example. Soy is one of the few complete plant proteins, so tofu is a great choice. Many plant-based protein powders are formulated to include all the essential amino acids.
Because it’s harder to get a good balance of amino acids with a vegan diet than an omnivorous one, and because plant-based protein sources are sometimes less digestible, some guidelines recommend that vegan athletes aim for a slightly higher total amount of protein than omnivores, just to be sure you’re covering all your needs. Others recommend making sure to get extra leucine, an amino acid that’s present in legumes and that you can also buy as a supplement.
Bottom line, you can build muscle on plant proteins, but you’ll have to put a little more thought into planning out your diet to make sure you get enough.