Skip to content

Solving The Protein Conundrum: A Guide To Building A Fit And Flourishing Body On A Plant-Based Diet

If you're considering a plant-based diet, you might wonder how to get enough protein. After all, protein is an essential nutrient that helps your body build and repair muscle, maintain healthy bones, and even boost your mood and cognitive function.

Solving the Protein Conundrum: A Guide to Building a Fit and Flourishing Body on a Plant-based Diet

Whether considering a vegetarian or vegan diet, how do you ensure you get enough protein without eating meat, dairy, or eggs?

You’re not alone if you’re wondering this. Many people are on the fence about transitioning to a plant-based diet because they fear they won’t get enough protein.

That’s where we come in—we’re going to break down everything you need to know about plant-based protein—including how much you need, where to get it, and some tips and tricks for getting enough daily protein. 

Whether you’re a seasoned pro at plant-based eating or just starting to explore it, you’ll have the information right here. Let’s dive in!

Just How Much Protein Do You Need?

Nuts and seeds as a source for plant-based proteins

Regarding protein, getting caught up in numbers and recommendations is easy. The truth is, the amount of protein your body needs depends on a variety of factors, including your:

  • Age
  • Gender
  • Physical activity level
  • Overall health

If you try to “google” how much protein you need, you’ll likely find various suggestions. However, some dietary recommendations can be misleading, so we’ve covered Evidence-Based Research for Protein Intake in a previous article. 


As we age, our body’s ability to absorb, digest, and utilize protein diminishes. The older we get, the more protein we need to maintain muscle mass, strength, and overall health.

Sarcopenia, the age-related loss of muscle mass, is a common issue in older adults. This condition can lead to a decline in physical function, increased risk of falls, and overall decreased quality of life. Consuming enough protein can help slow down or even prevent muscle loss, so older adults need to consume enough protein.

As we age, our appetite may decrease, making it harder to consume enough protein. For that reason, it’s important for older adults to choose nutrient-dense protein sources and to spread their protein intake throughout the day to ensure that they are getting enough.


Men need more protein than women due to their larger muscle mass. Still, this depends on their lifestyle. 

For example, active women in regular resistance training may need more protein to support muscle growth and recovery than inactive men. Similarly, pregnant and breastfeeding women may need more protein to support the growth and development of the fetus or infant.

Activity Level

Physical activity level plays a huge role in determining protein needs. If you’re physically active, you’ll have higher protein needs to support muscle repair and growth than someone with a sedentary lifestyle. 

For example, endurance athletes need more protein than others to support muscle repair and growth because of the constant wear and tear on their muscles during training and competition. Similarly, strength or resistance-trained athletes need extra protein to recover from training and maintain their muscle mass.

It’s worth noting that protein needs can also vary based on the type and intensity of the physical activity. A bodybuilder looking to gain a lot of muscle may require more protein than a runner looking to maintain muscle and support their body. 

Overall Health

Your body needs more than just protein to survive, and we require a diverse and balanced diet containing both macronutrients and micronutrients to stay healthy. Too much of anything is never good, and consuming too much protein can be hard for the body to metabolize and excrete. 

A high protein intake of up to 1 gram per pound of body weight (or 2.2 grams per kilogram) is generally safe. It’s also often beneficial for maintaining muscles, improving satiety, controlling blood sugar, and helping with weight loss. The upper tolerable limit for protein intake is 3.5 grams per kilogram of body weight per day. This is nearly impossible with a plant-based diet, though.

There’s no one-size-fits-all to this—which is why the best thing is to work with a healthcare professional or a licensed dietitian if you can, especially if you have kidney issues.  

What’s the Deal with Complete Protein?

Not all protein is created equal. Some proteins are better for you than others at helping you build muscles and supporting your other needs. So, you want to learn about protein quality and complete vs. incomplete proteins.

When it comes to plant-based proteins, some sources are considered complete proteins, and some are considered incomplete proteins. Technically, all of them are complete proteins, but some plant sources are low in certain amino acids.

Essential, conditionally essential, and non-essential amino acids.

A lot of proteins in your body contain all 20 essential amino acids. So, if you don’t have all 20, your body won’t be able to construct new proteins, including muscles. As a result, it will burn the other amino acids you have as energy instead of building new proteins. This is why you want to complete or complement your proteins every single day.

Here’s the difference between the two:

  • Complete proteins contain all the essential amino acids your body needs but cannot produce independently. These include animal-based proteins and proteins in quinoa, soy, potatoes, chia, and hemp.
  • Incomplete proteins are low in one or more of the essential amino acids. For example, grains are low in lysine but high in cysteine and methionine. In comparison, legumes are high in lysine and low in cysteine and methionine.  

Complementing your proteins is one way to ensure you get all the essential amino acids you need. You get all the essential amino acids (or complete proteins) by combining complementary incomplete proteins. For example: 

  • Rice and beans
  • Peanut butter on whole-wheat bread
  • Hummus with pita bread
  • Lentils and rice
  • Tofu and whole-wheat pasta

Another approach is to consume single plant-based protein sources that are considered to be complete proteins, such as:

  • Quinoa
  • Hemp seed
  • Chia seeds
  • Spirulina
  • Pumpkin seeds

Sometimes it’s impossible to complement all your proteins in a single meal. Generally, you want to complement your proteins in 24 hours so your body can use the amino acids you eat as building blocks.

Aside from completeness and quantity, protein quality also matters. A protein is high-quality when your body can use it easily. 

What is Protein Quality?

Plant-based protein powder as a complete vegan protein source

Protein quality refers to how effectively a protein supports the body’s growth and maintenance. The quality of a protein is determined by its amino acid profile, digestibility, and bioavailability.

  • The amino acid profile is the proportion of essential amino acids in a protein.
  • Digestibility refers is how easily your body can digest the protein
  • Bioavailability refers to how well your body can absorb and use the amino acids

Protein quality is especially important for people who want to build muscle, recover from injury or illness, or maintain a healthy weight. Also, vegetarians or vegans may consume various protein sources to get all the essential amino acids. Generally, plant-based proteins are lower quality because they are less complete and harder to digest.

The most widely used methods to measure protein quality include:

  • Protein Digestibility Corrected Amino Acid Score (PDCAAS) 
  • The Digestible Indispensable Amino Acid Score (DIAAS)

The Food and Agriculture Organization (FAO) and World Health Organization (WHO) developed these two methods to evaluate protein quality in food. DIAAS is considered more accurate than PDCAAS.


PDCAAS compares the amino acid requirements of humans to the amino acid composition of a protein, and assigns a score of 0 to 1. The highest score of 1 means that the protein is considered high quality, as it contains all of the essential amino acids in the correct ratio and in sufficient amounts to meet human needs.


DIAAS, a more recent approach, is an improvement over the PDCAAS. It takes into account the bioavailability of amino acids, the digestibility of the protein source, and its essential amino acids profile. If protein food scores are high on DIAAS, close to 100% of its indispensable amino acids are digested and absorbed. It means the protein food has very high protein quality. 

Problems with Soy as a Plant-Based Protein Food

Soy is a complete protein source.

Soy is a complete and bioavailable plant-based protein source with numerous health benefits. However, soy is also high in goitrogens and phytoestrogens. So, it may be best to limit soy products to 3 servings per week.

Phytoestrogens are plant compounds that mimic the effects of estrogen in the body. In excessive amounts, phytoestrogens may interfere with estrogen functions and may have negative effects on certain health conditions. 

Some men who rely on soy as a protein source report developing symptoms of high estrogen levels, such as man boobs. However, studies do not confirm this.

Goitrogens are substances that interfere with your thyroid function and inhibit iodine uptake. This can be an issue for people with thyroid problems but not necessarily for healthy people who consume moderate amounts of soy. Fortunately, the fermentation process may break down many of these goitrogens.

It’s worth noting that traditional soy-based foods like tofu, tempeh, and miso may be more healthful options than heavily processed soy products like soy protein isolate or textured vegetable proteins.  

Final Thoughts

You can get enough protein on a plant-based diet, but it requires a bit of planning, food preparation, and a variety of different sources. You want to focus on complete proteins and also be sure to complement your proteins.

It’s helpful to have a backup source of protein, such as Protein Breakthrough, which can help you reach your essential amino acids and protein needs for the day (and is also a tasty drink in-between meals). 

Also, high-quality plant-based protein-digesting enzymes like MassZymes and VegZymes can help you better digest and absorb your amino acids, even with lower-quality and harder-to-digest plant proteins. These enzymes allow our cofounder Wade T. Lightheart to build enough muscles to compete in Mr. Universe while eating 80 grams of proteins a day.

Whether you’re working on building muscle mass or supporting your cognitive functioning, there are plenty of options available to support a healthy, plant-based diet.

BIOptimize your digestion
Share this article using the buttons below
  1. Institute of Medicine (US) Committee on Military Nutrition Research. Amino Acid and Protein Requirements: Cognitive Performance, Stress, and Brain Function. National Academies Press (US); 1999.
  2. Elango R, Ball RO. Protein and Amino Acid Requirements during Pregnancy. Adv Nutr. 2016;7(4):839S – 44S.
  3. Rasmussen B, Ennis M, Pencharz P, Ball R, Courtney-martin G, Elango R. Protein Requirements of Healthy Lactating Women Are Higher Than the Current Recommendations. Current Developments in Nutrition. 2020;4(Suppl 2):653.
  4. Wu G. Dietary protein intake and human health. Food Funct. 2016;7(3):1251-1265.
  5. Joint WHO/FAO/UNU Expert Consultation. Protein and amino acid requirements in human nutrition. World Health Organ Tech Rep Ser. 2007;(935):1-265, back cover.
  6. Tujioka K, Ohsumi M, Hayase K, Yokogoshi H. Effect of the quality of dietary amino acids composition on the urea synthesis in rats. J Nutr Sci Vitaminol . 2011;57(1):48-55.
  7. Schaafsma G. The protein digestibility-corrected amino acid score. J Nutr. 2000;130(7):1865S – 7S.
  8. Sathyapalan T, Dawson AJ, Rigby AS, Thatcher NJ, Kilpatrick ES, Atkin SL. The Effect of Phytoestrogen on Thyroid in Subclinical Hypothyroidism: Randomized, Double Blind, Crossover Study. Front Endocrinol . 2018;9:531.
  9. Patisaul HB, Jefferson W. The pros and cons of phytoestrogens. Front Neuroendocrinol. 2010;31(4):400-419
  10. Reed KE, Camargo J, Hamilton-Reeves J, Kurzer M, Messina M. Neither soy nor isoflavone intake affects male reproductive hormones: An expanded and updated meta-analysis of clinical studies. Reprod Toxicol. 2021;100:60-67.[/custom-reference
  11. Babiker A, Alawi A, Al Atawi M, Al Alwan I. The role of micronutrients in thyroid dysfunction. Sudan J Paediatr. 2020;20(1):13-19.
Posted in
You'll enjoy these posts

Leave a Comment