Nutrition·April 26, 2026

Animal protein usually triggers stronger muscle building

Plant protein can still support muscle, but matching animal protein often requires better planning and enough total protein.

Educational, not medical advice. Always consult a qualified healthcare provider before changing your diet, supplements, or routine. Full disclaimer.

Nutrition

📈Recommendation

Treat animal protein as the more reliable muscle-building signal, especially when protein amount and calories are matched. Plant protein can still work, particularly soy and mixed plant foods, but the evidence suggests it often needs careful protein quality, food pairing, or larger portions to match animal sources.

🎓The findings

Muscle protein synthesis, or MPS, is the body’s process of building new muscle proteins after eating or training. Across the evidence, animal proteins tend to produce a stronger short-term MPS response than many plant proteins, especially soy and wheat in earlier studies [1]. The best direct whole-food comparison found that, in healthy older adults, a beef-containing omnivorous meal raised essential amino acids more and produced about 47% higher post-meal MPS than an isocaloric, protein-matched vegan meal [6]. Essential amino acids are the amino acids the body cannot make on its own. Longer-term trials are more mixed. A 2021 meta-analysis found no clear difference between animal and plant protein for absolute lean mass or strength, although animal protein favored percent lean mass, especially in younger adults [2]. A larger 2025 meta-analysis found a small advantage for animal protein on muscle mass, mainly when compared with non-soy plant proteins and plant-based diets; strength and physical performance did not differ significantly [3]. Soy looks closer to animal protein than many other plant sources. In the 2025 meta-analysis, soy and milk protein did not differ significantly for muscle mass, while animal protein outperformed non-soy plant proteins such as rice, chia, oat, and potato [3]. Resistance training changes the story. In young men doing supervised resistance training, a high-protein vegan diet built similar muscle and strength to a protein-matched omnivorous diet, suggesting plant-based diets can support adaptation when total protein is high and the diet is structured well [14].

🧬Why it works

The main biological issue is protein quality, not whether a food is “plant” or “animal.” Many plant proteins are less digestible, provide fewer essential amino acids per serving, and often contain less leucine, an essential amino acid that helps switch on muscle-building pathways [1], [5]. Some plant amino acids may be used more by the gut and liver before they reach muscle. This is called splanchnic extraction: more amino acids are retained in digestive organs rather than becoming available to muscle tissue [1], [12]. Older adults may be more affected because aging can blunt the muscle-building response to protein. This is called anabolic resistance. Reviews link it to weaker muscle signaling, reduced amino acid delivery, and greater amino acid retention outside muscle [9], [12]. Plant protein can be improved by combining protein sources, increasing portions, improving digestibility through preparation or processing, or improving amino acid balance. Reviews describe these as plausible strategies, but not all have been tested directly for post-meal MPS in humans [1], [4], [5].

⚠️Limitations

The evidence does not support a simple “plant protein fails, animal protein wins” claim. Soy often performs similarly to milk protein for muscle mass, and protein-matched vegan diets can support resistance-training gains in young men [3], [14]. Many studies test isolated proteins, short-term MPS, or specific foods, so they may not predict whole-diet outcomes. Plant proteins beyond soy, wheat, rice, chia, oat, potato, and Vicia faba peptide networks remain under-studied [1], [3], [15]. Few trials directly test sarcopenia as an outcome, and older adults, people with metabolic disease, and people with obesity may respond differently because anabolic resistance varies by health status [3], [12], [13].

👀Real-world example

A lifter choosing an omnivorous diet can rely on animal protein as a dense source of essential amino acids. A plant-based lifter can still build muscle, but the research points toward paying more attention to total protein, soy or mixed plant sources, and pairing protein intake with resistance training rather than assuming any single plant protein will match animal protein gram for gram.

📄 Primary paper

Higher Muscle Protein Synthesis Rates Following Ingestion of an Omnivorous Meal Compared with an Isocaloric and Isonitrogenous Vegan Meal in Healthy, Older Adults.

Pinckaers et al.

The Journal of nutrition, 2024

View paper on publisher website

🔗Sources

Numbers in brackets [1], [2]… in the body link to this list.

[1]
The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption.
van Vliet S, Burd NA, van Loon LJ · The Journal of nutrition · 2015
doi.org/10.3945/jn.114.204305
[2]
Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Lim MT, Pan BJ, Toh DWK, et al. · Nutrients · 2021
doi.org/10.3390/nu13020661
[3]
Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.
Reid-McCann RJ, Brennan SF, Ward NA, et al. · Nutrition reviews · 2025
doi.org/10.1093/nutrit/nuae200
[4]
Plant-based food patterns to stimulate muscle protein synthesis and support muscle mass in humans: a narrative review.
Nichele S, Phillips SM, Boaventura BCB · Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme · 2022
doi.org/10.1139/apnm-2021-0806
[5]
The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review.
Berrazaga I, Micard V, Gueugneau M, et al. · Nutrients · 2019
doi.org/10.3390/nu11081825
[6]
Higher Muscle Protein Synthesis Rates Following Ingestion of an Omnivorous Meal Compared with an Isocaloric and Isonitrogenous Vegan Meal in Healthy, Older Adults.
Pinckaers PJ, Domić J, Petrick HL, et al. · The Journal of nutrition · 2024
doi.org/10.1016/j.tjnut.2023.11.004
[7]
Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice.
Xia Z, Cholewa J, Zhao Y, et al. · Nutrients · 2016
doi.org/10.3390/nu8050246
[8]
Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group.
Deutz NE, Bauer JM, Barazzoni R, et al. · Clinical nutrition (Edinburgh, Scotland) · 2014
doi.org/10.1016/j.clnu.2014.04.007
[9]
Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group.
Bauer J, Biolo G, Cederholm T, et al. · Journal of the American Medical Directors Association · 2013
doi.org/10.1016/j.jamda.2013.05.021
[10]
Nutrition Management in Older Adults with Diabetes: A Review on the Importance of Shifting Prevention Strategies from Metabolic Syndrome to Frailty.
Tamura Y, Omura T, Toyoshima K, et al. · Nutrients · 2020
doi.org/10.3390/nu12113367
[11]
Emerging Targets and Treatments for Sarcopenia: A Narrative Review.
Cacciatore S, Calvani R, Esposito I, et al. · Nutrients · 2024
doi.org/10.3390/nu16193271
[12]
Age-related muscle anabolic resistance: inevitable or preventable?
Aragon AA, Tipton KD, Schoenfeld BJ · Nutrition reviews · 2023
doi.org/10.1093/nutrit/nuac062
[13]
Obesity and Metabolic Disease Impair the Anabolic Response to Protein Supplementation and Resistance Exercise: A Retrospective Analysis of a Randomized Clinical Trial with Implications for Aging, Sarcopenic Obesity, and Weight Management.
Nilsson MI, Xhuti D, de Maat NM, et al. · Nutrients · 2024
doi.org/10.3390/nu16244407
[14]
High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores.
Hevia-Larraín V, Gualano B, Longobardi I, et al. · Sports medicine (Auckland, N.Z.) · 2021
doi.org/10.1007/s40279-021-01434-9
[15]
Vicia faba Peptide Network Supplementation Does Not Differ From Milk Protein in Modulating Changes in Muscle Size During Short-Term Immobilization and Subsequent Remobilization, but Increases Muscle Protein Synthesis Rates During Remobilization in Healthy Young Men.
Weijzen MEG, Holwerda AM, Jetten GHJ, et al. · The Journal of nutrition · 2023
doi.org/10.1016/j.tjnut.2023.01.014