Animal-Based vs. Plant-Based Protein for Building Muscle & Staying Lean

As an athlete or fitness enthusiast, you're always looking for the best way to build and maintain muscle mass. One of the most crucial factors in muscle growth is protein consumption. However, with the rise of plant-based diets, you might be wondering if plant-based protein sources are as effective as animal-based protein sources. In this article, we'll compare the benefits and drawbacks of animal-based and plant-based proteins for muscle hypertrophy.

Animal-Based Protein

Animal-based proteins such as chicken, beef, and eggs are considered complete proteins because they contain all nine essential amino acids. These amino acids are critical for building and repairing muscle tissue (1). Animal-based proteins are also rich in leucine, a branched-chain amino acid (BCAA) that plays a vital role in muscle protein synthesis (2). However, animal sources of protein can be high in calories, saturated fat and cholesterol (1).

Plant-Based Protein

Plant-based protein sources like beans, lentils, quinoa, and tofu are low in saturated fat and cholesterol and contain other essential nutrients like fibre and antioxidants. Unlike animal sources of protein, plant-based sources are not complete sources of protein as they do not contain all of the essential amino acids in the same proportions (1). However, this can be mitigated by combining different plant-based proteins to provide the body with all the essential amino acids necessary for muscle growth.

Protein Density

Protein density refers to the percentage of calories that are from protein in a food. Lean animal-based protein sources tend to have a greater number of calories from protein than that of plant-based protein sources. For example, a 100-gram serving of chicken breast contains about 31 grams of protein, while a 100-gram serving of tofu contains about 8 grams of protein. High protein density foods can be beneficial if you are on a low-calorie diet and need to maximise the number of calories consumed from protein, while a low protein density can be beneficial if you are on a high-calorie diet and need to actually limit your protein intake.

Protein Density Graph.jpg Reproduced from Vliet et al., 2015 (2)

Leucine Content and Muscle Protein Synthesis

Muscle protein synthesis (MPS) is the process of building new muscle tissue. Leucine, one of the BCAAs found in protein, plays a crucial role in MPS (1). In general, animal-based protein sources have a higher leucine content than plant-based protein sources (2). This means less total protein can often be consumed from animal-based protein sources compared to plant-based sources to trigger MPS.

Leucine content % of total protein.jpg Reproduced from Vliet et al., 2015 (2)

Protein for max. MPS.jpg Reproduced from Vliet et al., 2015 (2)

Protein Source & Body Composition

A meta-analysis found that animal-based protein sources tend to result in a more favourable effect on lean muscle gain than plant-based protein sources, especially in young adults, but the difference was not statistically significant (3). It did, however, show that lean body mass percentage (i.e., the percentage of total body mass being made up of lean mass), was higher in diets with animal-based protein sources, meaning if achieving and maintaining a higher ratio of muscle mass to body fat is your goal, animal-based protein sources may be better. To add to this, the majority of the studies analysed were conducted on untrained people. It’s possible that if you are well-training and want to maximise the amount of muscle you gain, animal-based protein sources may become more advantageous due to their higher quality and bioavailability, especially if remaining lean is also your goal.

Muscle gain by protein source.jpg Taken from Lim et al., 2021 (3)


Both animal-based and plant-based protein sources have unique benefits and drawbacks for muscle hypertrophy. While animal-based protein sources are rich in complete protein and leucine, they can also be high in saturated fat and cholesterol. Plant-based protein sources are typically lower in overall calories but also have a lower protein density, often making it difficult to consume an adequate amount of protein on a low-calorie diet. Both sources can be adequate to facilitate muscle growth but animal protein consumption has been shown to result in a greater percentage of lean body mass than fat mass.

Ultimately, the choice between animal-based and plant-based protein sources depends on personal preference, values, goals, and overall dietary needs but both are suitable to build muscle.


  1. Jeukendrup, A. and Gleeson, M. Sport Nutrition. Champaign: Human Kinetics, 2019.
  2. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. Vliet, S., Burd, N. and Loon, L. 9, s.l. : The Journal of Nutrition, 2015, Vol. 145. 1981-1991.
  3. Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Lim, M. T., et al. 2, s.l. : Nutrients, 2021, Vol. 13. 1-18.

About the author

Daniel Brack

BSc., Pn1, CFT, SEN

From commercial pilot to fitness coach, Daniel changed careers to pursue his passion for health & fitness. He is the founder of Recalibrated Bodies and co-founder and Head Coach of Titan Fitness Algarve. He has a Bachelor of Science in Strength and Conditioning and is a Certified Fitness Trainer and Sports and Exercise Nutritionist. Daniel was an international IFBB men's physique competitor and is a father to two daughters. His passion is helping others become more educated and skilled to reach their health and fitness goals.

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