How much plant protein do you actually need to build muscle on a vegan diet?
Well, there is certainly no shortage of conflicting information on the subject.
Chances are you'll end up even more confused by trying to find an answer on the interwebs.
No wonder with not-so-brilliant advice floating around such as:
'Vegan person X eats Y amount of protein so that's what everyone should do'
'Just eat enough carbohydrate that will ensure you get adequate protein to build muscle and lose fat'.
I can't even...
So, if you're also tired of baseless claims and recommendations based purely on anecdotes and stupidity - and if you want the straight facts based on what scientific literature suggests to be an optimal intake...
...then read on to learn exactly how much plant protein you need to maximize muscle growth, both during bulking and cutting.
101 on Protein
You may or may not know all of this already, but I'll briefly run through the basics of just in case:
Protein is one of the three main macronutrients (along with carbohydrate and fat) that make up our diet.
When you consume protein, the digestive system breaks it down into what is called amino acids.
You see, protein molecules are actually made up out of hundreds and hundreds of these amino acids that are attached to each other in long strings.
These are the fundamental 'building blocks' for proteins - and it is the length and sequence of the amino acids that determines the characteristics of a protein molecule.
So when you eat protein it's broken down by the gut into the constituent amino acids...
...which then enter the bloodstream to be used by the body in a wide variety of ways (and I do mean wide variety as there are virtually endless combinations of amino acids):
Basically, you'd be having a hard time with this whole living thing without the required proteins to carry out thousands of vital tasks every day.
The group 'amino acids' can be divided into two broad groups:
Essential Amino Acids & Non-Essential Amino Acids
There are a total of 21 different amino acids that the body uses to build various proteins including muscle fibers.
In studies this is typically referred to as muscle protein synthesis (MPS), the process where cells take amino acids and put them together into a new protein.
9 of these amino acids cannot be synthesized in the body, thusly they're called essential amino acids (EAA):
*Branched chain amino acids (BCAAs)
So while the body can make all the nonessential amino acids it needs from scratch...
...we have to rely on food to obtain these 9 essential amino acids.
And here's where the concept of 'protein quality' comes into play:
Different foods have different amino acid profiles, which essentially are lists of much of each essential amino acid is present a food.
For instance, here's the amino acid profile of 100 g of cooked lentils:
Here is one of the aspects where animal proteins and plant proteins starts diverging from one another:
Animal products, such as meat, dairy and eggs, contain protein that is considered to be 'optimal' or 'complete'.
That is to say, animal protein has an amino acid profile with ideal proportions of all the nine essential amino acids for the human body to use.
I hope that sentence made sense.
Plant proteins on the other hand, generally speaking do not provide an ideal proportion of the 9 essential amino acids.
Hence why they've been dubbed as 'incomplete' or 'non-optimal' proteins.
The Myth of "Incomplete Protein"
Because plant proteins typically have a shortage of one or two of the essential amino acids, protein combining used to be a popular practice back in the day.
It was based on the notion that you had to combine different plant foods in meals, to make up for the shortcomings of plant protein and provide your body with all of the amino acids in optimal amounts.
Luckily we now know better.
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 picture comparing the essential amino acid profile of rice protein 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:
So the hypothesis behind protein combining was that you needed combine foods from 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 just 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.
Granted you actually eat enough plant protein throughout the day, that is (we'll get into that topic soon I promise).
Moreover, there's 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...)
Plant Protein vs Animal Protein
We've established that vegan sources of protein aren't 'incomplete' and that obsessing over combining plant proteins is almost certainly not needed.
Having that said...
...does plant protein have the same anabolic i.e. muscle building capacity as animal protein does?
You can try and answer the question by looking up figures such as DIAAS and PDCAAS - scores constructed to determine the overall quality of proteins.
Which is not a bad idea to get an overview of different proteins, however the problem with these numbers is that they view and rate protein sources as isolated nutrients.
For example cooked kidney beans have a DIAAS score of 0.59 - which makes it sound like the protein in kidney beans is really, really crappy.
I wouldn't want to base my protein around something with a score of only 0.59.
But here's the kicker:
Due to the way the formula is designed, it caps the score at any rate-limiting amino acid, which in the case of legumes such as kidney beans is methionine + cysteine.
As we have discussed already this does not matter if you eat a variety of plant proteins throughout the day.
So to answer this question we'll have to take a different, completely non-biased look at the subject:
Branched-Chain Amino Acids in Plant vs Animal Sources of Protein
One gram of beef protein provides the same amount of protein as one gram of rice protein.
Okay written out like that it sounds rather obvious.
What does differ though, is how many essential relative to non-essential amino acids are present in each gram protein.
And the protein with the largest proportion of essential amino acids will be your best bet if you want as much muscle growth as possible.
There are two reasons for this:
Firstly, a shortage of any essential amino acid will quickly become rate limiting for muscle protein synthesis.
That means the more EAAs you have running through your blood stream the better - so that there are always available building blocks for new muscle tissue to be made.
Secondly, a sub-group of the EAAs called the branched chain amino acids, or BCAAs, are especially important for triggering muscle growth.
These include leucine, isoleucine and valine.
What's so special about them, you ask?
Well, they account for 35% of the essential amino acid content in muscle protein, increase muscle protein synthesis and reduce protein degradation by activating key enzymes in muscle protein synthesis.
Recently it's been theorised that the key player here is leucine:
Leucine content of a protein directly impacts protein synthesis and muscle hypertrophy, and it's been found that 3-4 grams of leucine per meal is needed to maximally stimulate protein synthesis.
With that information in mind, let's directly compare a plant source of protein to a animal protein.
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)
As you can plainly see, the egg protein does have an edge over the soy bean protein.
More precisely, the eggs contain 14.532 mg of EAA compared to the soy beans at 12.909 mg.
= 12.6% more essential amino acids.
Additionally the egg also wins in the BCAA department with more leucine, isoleucine and valine.
Alright, here's the key takeaway:
When you take any plant protein and compare it to animal protein, the animal protein will in 99.9% cases 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, but maybe you do).
A ballpark estimate would perhaps be around 10-15%, which may theoretically translate into 10-15% less muscle building potential.
Digestability of Plant vs Animal Protein
A protein's efficacy in promoting muscle hypertrophy also depends 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.
The gist when it comes to protein digestability is, unfortunately, that plant protein tends to not digest as well as animal protein.
Here are some different numbers for various foods:
...and here are a couple of more numbers for digestability of foods from this study done on rats (where you also can see that there's a significant difference between using the ileal or fecal method):
Bottomline here is that 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 rule of thumb, animal protein is digested about 10% better than plant protein.
What About Vegan BCAA Supplements?
I figured it would be a good idea to address this issue.
Considering the relatively low(er) BCAA content in plant protein - it would kind of make sense to supplement them in order to maximize protein synthesis as a vegan...
Maybe, and maybe not.
Before we jump the gun it's nice to have some scientific data backing up the BCAA supplements...
...and as it turns out there's not a whole lot of it.
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."
Then why does it seem like all huge vegan bodybuilders use and promote vegan BCAA supplements?
I don't know. Money, perhaps?
Vegan BCAAs are probably not a direct danger to your health, and if you've got the extra money in your bank account then go for it...
...but for the vast majority of people it's probably a waste of money. Money that you could spend on scientifically-backed supplements that actually work.
Or spend the cash on plant foods.
There's just tons of BCAA in high-protein vegan foods, below is the amino acid breakdown of a substantial vegan bodybuilding meal:
2 cups of black beans, 2 cups of brown rice and 2 cups of broccoli.
That's 46.8 grams of protein, 8.6 grams of BCAAs and 3.7 grams of leucine in one meal.
How Much Plant Protein Do You Need to Build Muscle?
At this point we've looked at some of the physiological functions protein and the key differences between plant protein and animal protein.
Now for the part you've all been waiting for:
How many grams of protein do you need to optimally build muscle on a vegan diet?
Well for starters we 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.
However this RDA is designed for the general population, and based on essentially sedentary individuals.
What the current body of sports nutrition research indicates is that this is not enough for athletes, that can have considerably greater protein needs to maintain muscle mass.
How much greater are these protein needs then?
Last year a couple big names in the evidence-based, fitness and nutrition world (Phillips SM, Henselmans, Alan Aragon, Brad Schoenfeld among others) published a massive meta-analysis of all studies done on protein supplementation and muscle and strength gains.
Here's the key takeaway from that study:
Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM.
Or put another way, eating ~1.6 grams of protein per kg bodyweight, or about 0.73 g protein per lbs, will maximize your muscle and strength gains.
Any more than that didn't seem to have any further positive effect.
Or is it?
You see, there can actually be rather large differences between individuals in how much protein is needed to just maintain muscle mass.
This review found 1.6 g protein per kg to be the mean optimal intake, which basically means that for most people it will work optimally.
However there are always outliers and some individuals may do better with more protein, and some with less.
The authors bring this point up and recommend another number that would cover the needs of any outliers:
...it may be prudent to recommend ~2.2 g protein/kg/d for those seeking to maximise resistance training-induced gains in FFM.
And so with taking into account this inter-individual variance in protein needs...
... a range of 1.6-2.2 g protein per kg (or around 0.7-1 g protein per lbs) would be appropriate to cover the needs of the majority of athletes, bodybuilders and lifters.
So, if you want to maximize your vegan muscle and strength gains go with:
1.6-2.2 grams of protein per kilogram per day.
An important thing to realize here, is that these numbers do not expect all protein sources you consume to be super well-digested and exceptionally rich in essential amino acids.
You see, protein recommendations are based on 'normal' diets - i.e. where some protein is animal-based, a lot of it is plant-based, some well-digested and some not so much.
Which means it already factors in some of the shortcomings of plant protein.
However to indulge in speculation, I would recommend shooting for the higher end of this range seeing as:
- Animal protein contains ~10-15% more essential amino acids than plant protein.
- Animal protein is digested ~10% better than plant protein.
- Animal protein generally speaking is more anabolic (contains less leucine) than plant protein.
Personally I aim for 2 g of protein per kg so that I know I get in all the EAAs and muscle-building leucine every meal.
But you do you.
Beyond maximizing muscle protein synthesis, a higher protein intake can also provide other benefits such as:
So feel free to higher on protein if you want... but do it within reason so you don't need to drastically cut down carbohydrate or fat - both of which are required for optimal health and physical performance.
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 beans, tofu 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:
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!
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!