In the Netflix documentary “The Game Changers”, a peanut butter sandwich goes head-to-head with ground beef as a protein source, suggesting they’re equal contenders. At ZION Performance, we often hear clients tout peanut butter as their breakfast go-to protein source. But when it comes to the best protein sources for muscle growth, is it as simple as the nutrition labels imply? While plant proteins like peanut butter contribute to your daily intake, the science points to animal proteins—like beef, eggs, and whey—as the superior choice due to their amino acid profiles, digestibility, and muscle-building efficiency.
Why Animal Proteins Top the List for Muscle Growth
When searching for the best protein sources for muscle growth, animal proteins consistently stand out. Options like beef, chicken, eggs, and dairy are packed with essential amino acids (EAAs)—nutrients your body can’t produce on its own. Among these, leucine is the star, driving muscle protein synthesis (MPS) to repair and build muscle after workouts or injury. Animal proteins boast leucine levels of 8-11% in their amino acid makeup, outpacing most plant proteins, which hover at 6-8% (Berrazaga et al., 2019).
Digestibility is another reason animal proteins rank among the best protein sources for muscle growth. Metrics like the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) and Digestible Indispensable Amino Acid Score (DIAAS) show whey and eggs hitting perfect scores of 1.0, while peanuts lag at 0.52 (Mathai et al., 2017). The DIAAS further confirms animal proteins deliver more bioavailable amino acids, triggering a stronger muscle-building response gram for gram (Phillips et al., 2020). Simply put, animal proteins are a more efficient choice for maximizing gains. We’ve also seen high plant protein diets cause significant gastrointestinal distress over time, likely due to these digestibility scores.
Beyond amino acids, animal proteins offer extras like creatine, taurine, carnosine, and collagen—compounds scarce in plant foods. Creatine boosts athletic performance, while collagen supports joint health, making animal options some of the best protein sources for muscle growth and overall fitness.
Plant Proteins: Valuable, but Less Potent for Muscle Building
Plant-based proteins like peanut butter, lentils, and quinoa aren’t useless—they can contribute to muscle growth when consumed in higher amounts. Studies show vegans and vegetarians can match omnivores in strength gains if protein intake is sufficient (Rogerson, 2017). However, they don’t top the list of best protein sources for muscle growth due to lower leucine levels and digestibility. Peanut butter, for example, offers 6.5% leucine and a DIAAS of 0.4-0.5, compared to beef’s 1.1 (Berrazaga et al., 2019). To rival 20-25 grams of whey, you’d need 30-40 grams of pea or rice protein.
Strategizing helps. Combining plant sources—like rice (high in methionine) and beans (high in lysine)—creates a more complete amino acid profile. High-quality options like soy, quinoa, and peas are solid choices (Hirsch et al., 2021). Plus, plant proteins bring fiber, antioxidants, and unsaturated fats, offering heart and anti-inflammatory perks (Craig, 2009). Still, they often lack B12, omega-3s, and zinc—nutrients abundant in animal foods—requiring supplements for balance.
Practical Challenges in Muscle-Building Diets
For athletes chasing the best protein sources for muscle growth or your average person looking to maintain or grow muscle, plant-based eating can complicate hitting the 1.6-2.0 grams of protein per kilogram of body weight needed daily (Rogerson, 2017). High-fiber foods like beans fill you up fast, while animal proteins like chicken deliver dense protein with less bulk. Vegan athletes may also need creatine or beta-alanine supplements, as these muscle-boosting compounds are minimal in plants.
Eating on the go adds another hurdle. While plant-based options are growing, securing enough protein from a vegan meal—beyond a peanut butter sandwich—takes effort. At home, techniques like soaking, sprouting, or fermenting can enhance plant protein absorption (Hirsch et al., 2021).
The Peanut Butter Pitfall
So, where does peanut butter land among the best protein sources for muscle growth? With 7 grams of protein per 2 tablespoons, it’s convenient but underwhelming. Its lower leucine and digestibility pale next to ground beef’s 25 grams per 3-ounce serving. The Game Changers may hype it up, but as nutrition expert Alan Aragon explains, “Animal-based protein is generally more anabolic gram-for-gram,” even if plant proteins can work with higher totals.
Finding the Best Protein Sources for Your Goals
The plant vs. animal debate isn’t about picking a side—it’s about trade-offs. Animal proteins lead as the best protein sources for muscle growth due to their efficiency and anabolic power. Plant proteins, while less potent, offer broader health benefits and can suffice with planning. Whether you’re spreading peanut butter or searing steak, both fit a balanced diet plan. At ZION Performance our priority is to get people to grow and maintain muscle so they can live a long, full, independent life. Which you can accomplish with all of the above!
For plant-based eaters, target 1.6 grams of protein per kilogram daily, blend complementary sources, and prioritize whole foods. For omnivores, animal proteins are the easiest route to muscle gains. Either way, peanut butter isn’t among the best protein sources for muscle growth—it’s just a tasty sidekick.
Sources:
Berrazaga I, Micard V, Gueugneau M, Walrand S. The Role of the Anabolic Properties of Plant-versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients. 2019 Aug 7;11(8):1825. https://pmc.ncbi.nlm.nih.gov/articles/PMC6723444/
Craig WJ. Health effects of vegan diets. Am J Clin Nutr. 2009 May;89(5):1627S-1633S. doi: 10.3945/ajcn.2009.26736N. Epub 2009 Mar 11. PMID: 19279075. https://www.sciencedirect.com/science/article/pii/S0002916523238356?via%3Dihub
Hirsch, K. R., Wolfe, R. R., & Ferrando, A. A. (2021). Pre- and Post-Surgical Nutrition for Preservation of Muscle Mass, Strength, and Functionality Following Orthopedic Surgery. Nutrients, 13(5). https://doi.org/10.3390/nu13051675
Mathai, J. K., Liu, Y., & Stein, H. H. (2017). Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than values calculated using the concept for protein digestibility-corrected amino acid scores (PDCAAS). The British Journal of Nutrition, 117(4), 490–499. https://doi.org/10.1017/S0007114517000125
Phillips, S. M., Paddon-Jones, D., & Layman, D. K. (2020). Optimizing Adult Protein Intake During Catabolic Health Conditions. Advances in Nutrition (Bethesda, Md.), 11(4), S1058–S1069. https://doi.org/10.1093/advances/nmaa047
Rogerson D. Vegan diets: practical advice for athletes and exercisers. J Int Soc Sports Nutr. 2017 Sep 13;14:36. doi: 10.1186/s12970-017-0192-9. PMID: 28924423; PMCID: PMC5598028. https://pmc.ncbi.nlm.nih.gov/articles/PMC5598028/