Animal Vs. Plant Protein For Muscle Building

Animal Vs. Plant Protein For Muscle Building

When trying to build muscle there is one thing that every athlete knows. From the trainee who just stepped into the gym for the first time to the professional bodybuilder; you need to eat a lot of protein.

How Much Protein Should You Eat?

You should be consuming 1g of protein per pound of bodyweight (or about 2.2 grams per kilogram of bodyweight) a day, which your body then breaks down into amino acids that are used for countless processes in the body. One of these processes that athletes are concerned about is known as muscle protein synthesis or the growth of new muscle.

The main amino acid that is used for stimulating muscle protein synthesis is known as leucine and can be found in many protein sources. Like carbohydrates and fats though, not all protein sources are made equal. Some contain higher levels of leucine and the other eight essential amino acids that we need to get in our diet. This has been the main fuel for a long standing debate on what source of protein is better, usually divided by whether it is animal sources or plant sources.

In this article we will be discussing how much protein can be found in plant sources and animal sources as well as how levels of leucine can differ between sources (and why it matters).

animal vs plant protein

How Does Animal & Plant Protein Differ?

When it comes to low fat, low carb protein sources, we usually think of meat as the best source. This is definitely the case until we talk about powders. From a whole food perspective, high protein diets are much harder to fulfill on a vegan lifestyle. When looking at the numbers, it isn’t even close.

For comparison it would take over two pounds (about one kilo) or 1,110 calories of quinoa to achieve 40 grams of protein, while it only takes eight ounces (or about 220 grams) or 200 calories of chicken breast to also achieve 40 grams of protein.

The only animal free food source that can compete with lean meat sources is soy protein, in the form of tofu, tempeh, etc. An eight ounce serving of tempeh will also deliver 40 grams of protein and 450 calories (due to extra fat and carbs). The issue with this is a lack of variety, as meatless whole food sources that are high protein are very limited while omnivorous athletes can consume seemingly limitless varieties of meats along with everything vegans eat. Protein powders are a different conundrum though.

As stated in the introduction, protein sources are less cut and dry than just the number game. Levels of important amino acids are higher in different foods, which can impact overall muscle growth. Using soy again as an example (this time in the form of soy isolate powder), the macronutrients are very similar to whey protein powder:

Soy Protein Isolate: 30 gram serving, 120 calories, 26 protein, 1 fat, 0.5 carb.

Whey Protein Isolate: 30 gram serving, 120 calories, 25 protein, 0 fat, 1 carb.

These numbers are almost indistinguishable from each other at a glance, but their amino acid profiles speak a different story.

LEUCINE BCAA 1546 2609
ARGININE 1428 480
LYSINE 1184 2222
TOTALS 9039 10491


As you can see, these numbers are quite different, especially when it comes to the most important amino acid for muscle growth, leucine. To put these numbers in perspective, it would take almost two times as much soy protein to reach the amount of leucine that is present in whey. This is where something known as the leucine threshold comes in, or the amount of leucine required to create the most anabolic (muscle building) state in the body for a few hours. Current research shows that 3.5-4 g of leucine is enough to put your body in “muscle building mode”.

Looking back at the amount of leucine in soy and whey, it would take only 1.5 servings of whey to reach this threshold, while it would take over two servings of soy to reach it. Unfortunately other vegan protein powders contain even less leucine than soy, with rice protein powder containing 1400 mgs per 26 grams, pea protein powder containing 1300 mgs and hemp containing 600 mgs.

animal vs plant protein

Take Home Message

So is this the end of the debate for which source of protein is best? Not quite, as it is very possible to still build impressive amounts of muscle with only plant proteins. While it will take a larger appetite to consume enough protein to fulfill the leucine threshold, it can be done easier when taking advantage of certain supplements. The most important of which is pure leucine powder, which is quite cheap when bought in bulk. When mixed with a soy/pea/rice protein shake, it will help you reach that leucine threshold and put your body in an anabolic state. For whole foods it will be important to prioritize higher protein foods such as beans, nuts, forms of soy, and seeds/grains. While it will always be easier for meat eaters to get in enough leucine rich protein to gain muscle, always know that as a vegan or vegetarian, it is very possible when done correctly.


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Billy Galipeault

Billy Galipeault

Writer and expert