How Much Plant Protein Do You Need to Build Muscle?

If you're interested in vegan fitness you've probably wondered:

How much plant protein is actually needed to build muscle on a vegan diet?

There is no shortage of conflicting information on the subject - most likely you'll just end up more confused by trying to find a straight answer on the interwebs. 

I've seen advice range from 'Don't worry just eat enough bananas!!!' to 'Incomplete protein sucks, you have to supplement with X, Y and Z'.

Not super helpful. 

Well here's the truth:

Plant protein can absolutely aid you in putting on slabs of muscle (there's tons of people who have done it)...

... but there are some question marks that needs to addressed such as digestability and essential amino acid content.

In this article I will dissect the issue of protein on a vegan diet, with all the nitty-gritty concerning protein quality etc, and so you will know exactly how much plant protein you need to maximize muscle growth.

Let's do it. 

Why your body needs protein

3 types of lentils

You may or may not know all of this already, but I'll briefly run through the basics of just in case:

In the body, protein molecules are made up of hundreds of smaller units called amino acids that are attached to each other in long strings.

These amino acids are the 'building blocks' for proteins - and depending on the length and sequence of the amino acids the resulting protein will have different properties. 

Hence why they are responsible for such a wide range of functions in the body including:

They make up our enzymes i.e biological catalysts, antibodies that help our immune system, hormones such as insulin, a wide range of peptides and molecules such as the organic acid creatine, provide structure and support for cells and transport molecules from one location to another.

Phew.

Essential amino acids & nonessential amino acids

amino acids chain

Now if you're reading this you're probably most interested in the building of muscle proteins.

There are a total of 21 different amino acids that the body uses to build various proteins (and also our muscle fibers).

9 of these amino acids cannot be synthesized in the body, thusly they're called essential amino acids (EAA).

Here they are in all of their glory:

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine + Cysteine
  • Phenylalanine + Tyrosine
  • Threonine
  • Tryptophan
  • Valine

So while the body can synthesize all the nonessential amino acids it needs, we have to rely on food for the other 9 essential amino acids.

When you eat a food that contains protein, the digestive system breaks down the protein molecules into its components, the amino acids. 

Here's where plant protein starts to differ from animal protein.

Animal products, such as meat, dairy and eggs, are all sources of what is known 'complete protein'. These proteins contain an ideal or adequate proportion of all the nine essential amino acids necessary for the body to utilize in building muscle. 

Plant proteins on the other hand (with a few expections) have a shortage of one or several of these essential amino acids. This is why they've been dubbed as 'incomplete proteins'.

However as we will discover soon this labeling of plant protein as 'incomplete' is not really accurate.

A particular sub-group of the esssential amino acids, the branched-chain amino acids (BCAAs), isoleucine, leucine and valine, are especially important for stimulating muscle growth. Leucine in particular plays a vital role in triggering muscle protein synthesis. I'll return to this subject later on.

The myth of "incomplete protein"

You've probably heard about the theory of protein combining:

That you need to combine different plant proteins in meals to get a complete protein with all of the essential amino acids.

Well, this is probably one of the oldest myths related to the plant-based diet - let's debunk it once and for all (fingers crossed).

Below is a figure comparing the essential amino acids present in rice protein and lentil protein.

amino acid breakdown of rice and lentil protein

Do you see any 'incomplete protein' or 'deficiency in amino acids'?

Cause' I don't.

As you can plainly see, neither of these plant proteins are incomplete as all of the nine essential amino acids are present.

Further examining the amino acid profile of each protein you'll notice that they're quite similiar, with the exception for two amino acids lysine and methionine + cysteine. 

Rice lacks in lysine but has more of methionine + cysteine, and vice versa for the lentil protein. 

I deliberately chose these two plant proteins as they illustrate the basis of the outdated rule of choosing complementary proteins:

  • Legumes as a group, lentils, beans and peas etc, contain plenty of lysine but not so much methionine + cysteine. 
  • Cereals as a group, rice, wheat, oatmeal etc, contain less lysine but more methionine + cysteine. 

So the hypothesis of protein combining was that you needed combine foods from each of these two categories, otherwise the protein would be rendered useless (or something like that).

Well since the idea first emerged in the 70's this has been proven be absolute theoretical nonsense.

There is no need micromanage your diet in this meticulous manner.

Here's the position of the American Dietetic Association and Dietitians of Canada on ​the matter of protein combining:

"Research indicates that an assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults, thus complementary proteins do not need to be consumed at the same meal."

If your vegan diet includes a variety of plant foods, your body will have access to all the essential amino acids it requires for synthesizing new muscle tissue. 

There is constantly a buffer of amino acids floating around in our bloodstream available to be used. This amino acid pool, which is the size of about 120-130 grams in an adult male, consists of dietary protein and degraded protein from body tissue.

So any minor shortage of a specific amino acid in a meal, can be completed from your previous meal found in this pool of circulating amino acids.

Our body is pretty smart, it takes care of this stuff for us. Just don't be silly and eat a mono oatmeal diet (I just googled it and it's a thing apparently...)

Determining the quality of plant protein

green peas

I believe we've busted the myth of protein combining.

Great, let's finally move on.

Now:

Does plant protein have the same anabolic or muscle building capacity as animal protein does? 

And to answer that question we have to examine two different factors:

Essential amino acid content and digestability.

(Please note that this discussion is strictly judging a protein by how well it promotes muscle hypertrophy. For overall health I think it's pretty obvious which is the far superior option, but that's beyond the scope of this article)

Essential amino acid content of plant protein

Obviously one gram of protein from beef is the exact same quantity of one gram of protein from rice (duh.) 

What differs though is the proportion of the amino acids...

.... and for muscle growth we want to consume as many essential amino acids as possible.

So per gram of protein, how does plant protein stack up to animal protein in terms of EAAs?

To shed some light on the matter I made another chart (cause' who doesn't love charts) comparing the essential amino acids found in 28.6 grams of protein from cooked soybeans versus 28.6 grams of whole eggs. 

(Why 28.6 grams? I don't know, stop asking questions)

soybeans vs eggs

1000's mg on the vertical axis.

As you can see, the egg protein does have a slight edge over the soy bean protein.

More precisely the eggs provide 14.532 mg of EAA compared to the soy beans at 12.909 mg. 

That's about 12.6% more EAA.

Now egg protein is extremely tough competition for any other protein, it's recognized as perhaps the gold standard in terms of amino acid composition. If we would've compared soy protein to any other animal protein (such as chicken protein), the difference wouldn't have been as big. 

Anyways, this is still consistent across the board for plant vs animal protein - animal protein does boast a higher EAA content. 

An exact number for how much more is hard to determine as we would have to compare all plant proteins with all animal proteins (I don't have time for that, neither does anyone). A ballpark estimate would perhaps be around 10-15%. 

Digestability of plant protein

animal eating carrot

A protein's effectiveness is also going to depend on how well your body digests and utilizes the protein.

For example, eating 100 grams of protein X and absorbing 84 grams yields a digestability of 84/100=84%.

Now, there are different ways of determining protein digestability:

You can either measure digestability of individual amino acids or as whole proteins, fecal or ileal digestability (in the poop or in the final part of the small intestine), you can use different animals such as rats, pigs or humans...

... all of which will yield slightly different results.

Okay I get it you're not interested in if you measure protein in the poop or elsewhere.

So the gist when it comes to protein digestability is that plant protein tends to not digest as well as animal protein. 

Here are some different numbers for various foods:

  • Eggs: 97%
  • Milk and cheese: 95%
  • Beef: 98%
  • check
    Casein: 99%
  • Canned pinto beans: 79%
  • Lentils: 85%
  • Fababean: 86%
  • Rolled oats: 91%
  • Rice: 88%
  • Wheat: 86-93%
  • Refined wheat, flour: 96%
  • Pea protein concentrate: 92%
  • check
    Soy protein isolate: 95%

...And here are a couple of more numbers for digestability of foods (where you also can see that there's a significant difference between using the ileal or fecal method):

In summary, we seem to be better at digesting animal protein than plant protein (with the expection of plant protein powders that are digested just as readily).

As a general rule of thumb, animal protein is digested about 10% better than plant protein.

What about vegan BCAA supplements?

So I promised I would elaborate more on the branced-chain amino acids, or BCAAs.

This group of essential amino acids is compromised out of leucine, isoleucine and valine.

They account for 35% of the essential amino acids in muscle protein, promote protein synthesis & anabolic signaling and are also primarily metabolized in muscle tissue.

Naturally muscle seekers like the idea of supplementing additional BCAAs as they activate key enzymes in muscle protein synthesis (especially leucine that on it's own is a powerful trigger of MPS).

As illustrated in the chart comparing soy and egg protein, you can see that the BCAA content is lower in the soy protein.

So with that in mind it would kind of make sense to supplement BCAA in order to maximize protein synthesis as a vegan... right?

Maybe, and maybe not. Before we jump the gun it's nice to have some scientific data backing up the effiency of BCAA supplements...

...and as it turns out there's no evidence whatsoever. 

In the paper Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy the authors state that

"we find shockingly little evidence for their efficacy in promoting MPS or lean mass gains and would advise the use of intact proteins as opposed to a purified combination of BCAA that appear to antagonize each other in terms of transport both into circulation and likely in to the muscle "

Another recent review on the current body of research on BCAAs and protein synthesis arrived at the same conclusion:

"We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted."

To put one more nail in the coffin for BCAA supplements, below is the amino acid breakdown of a pretty standard vegan bodybuilding meal:

2 cups of black beans, 2 cups of brown rice and 2 cups of broccoli.

amino acid breakdown of vegan meal

Stats pulled from cronometer.

That's 46.8 grams of protein, 8.6 grams of BCAAs and 3.7 grams of leucine in one meal.

And right around 3-4 grams of leucine per meal has been shown to maximally stimulate protein synthesis. 

In light of these recent reviews that fail to find any benefits of BCAA supplements, and considering that you obviously can get all the BCAA you need from high-protein plant foods, I see absolutely no benefit to supplementing BCAA in hopes of growing more muscle. 

How much protein do you need to build muscle?

man lifting weights

We've established some of the key differences between plant protein vs animal protein (and why BCAAs are probably a total waste of money).

Now for the part you've all been waiting for:

What kind of protein numbers are we looking at for optimal muscle growth?

Well for starters we probably don't need a gazillion or even millions of grams per day. 

According to U.S. and Canadian dietary reference intakes 0,8 g protein per kg is enough to meet the nutrient requirement of nearly all (~98%) healthy individuals.

The same panel that established the RDA also states that “in view of the lack of compelling evidence to the contrary, no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise”

For a person weighing 70 kg or 154 lbs, the RDA equates to 56 grams of protein. 

chicken eating grains

‘But mah PROTEIN!!!!’

Yes, sports nutrition research indicates that for athletes that wants to improve body composition and performance, a higher protein intake than the current RDA can be beneficial.

No, still not a valid reason to eat the guy in the picture above. He is adorable and is not to be killed for completely trivial reasons.

1.3-1.8 g protein per kg seems to be the optimal range for us that are interested in gaining muscle mass and maximizing muscle protein synthesis (according to this, and this, and this, and this review of protein needs).

Now, beyond maximizing muscle protein synthesis, a higher protein intake can also provide other benefits such as: 

If you are planning to get seriously lean for a bodybuilding show (which entails tons of cardio, weight training, a drastic reduction in calories etc) some preliminary evidence suggests that an even higher protein intake of 2.3-3.1 g/kg of LBM might help with maintaining positive nitrogen balance. 

Once again this is for elite bodybuilders, not for the vast majority of people that simply want to look great naked or improve performance/get as strong or athletic as possible.

Protein recommendations for vegans

vegan meal

We know for a fact that there's less essential amino acids in plant protein and that it's not digested as well as animal protein. 

Does that mean you should compensate by eating more plant protein? 

These reviews of protein intake I've referenced do not provide separate recommendations based on protein quality - which means we'll have to make our own educated guess. 

Firstly, it's important to realize that these protein recommendations of 1.8 g/kg or any other number are not based on flawless diets consisting of protein that is digested at 101% efficiency with an excellent amino acid profile.

They are based on what a diet usually looks like:

Some animal-based protein, a whole lot of ‘incomplete’ protein, some protein sources that are well digested and some not as well digested. 

Which means that the figures for protein already factors in the lower EAA content and lowered digestability of plants. 

Still, when you derive all your protein from generally speaking less anabolic plant sources, I'd say it's a wise choice to err on the side of caution. 

To compensate for the overall lower quality of plant protein (and to get plenty of the all-important BCAAs for muscle building), my recommendation is to stay at the higher end of the range for protein intake at around 1.8 g protein per kg, or 0.82 lb per lbs.

Awesome sources of vegan protein

Unsure as to how to actually get all of the vegan protein in your diet?

Don't fret, it's actually quite easy if you simply know where to look.

Traditional 'carb sources' such as whole grains, starchy roots and vegetables all contain protein.

At the end of a day's worth of vegan eating you'll be surprised how much protein you get from foods such as oatmeal and broccoli.

400 grams of broccoli is more than 10 grams of protein and 100 g of oatmeal provides 17 grams of protein!

However the most protein-dense plant group is legumes, that is lentils, peas and beanstofu and tempeh and so on and so forth.

These are absolutely packed with protein and they also contain plenty of BCAA.

Another hassle-free way of getting enough protein is to simply include a vegan protein shake or two per day.

Here are some great vegan protein sources:

  • Red, green and brown lentils
  • Chickpeas
  • Black beans
  • leaf
    Kidney beans
  • leaf
    Edamame
  • leaf
    Tofu
  • leaf
    Tempeh
  • leaf
    Seitan (faux meat made from wheat-gluten)
  • leaf
    Vegan protein powder
  • leaf
    Oatmeal
  • leaf
    Quinoa
  • leaf
    High-protein vegetables such as green peas, broccoli, spinach and mushrooms

Alright I think that's pretty much it for vegan protein. I hope you found some of the information useful. 

I'd love to hear what your thoughts are about protein intake on a plant-based diet in the comments!

 🙂

'Spread the Vegan Word'!
  • Alex
  • December 8, 2017
Alex
 

Hey there! I'm Alex and I'm obsessed with a vegan diet, strength training and bodybuilding, as well as health and nutrition. When I'm not writing articles on here I am either in the gym, playing electric guitar or cooking vegan food!

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