animal or plant protein?

1. What You Hear
  • Animal protein is always superior for muscle growth and health.
  • Plant proteins can't build muscle effectively.
  • You must eat animal protein to maintain or gain muscle.
  • Plant proteins are incomplete and inferior for nutrition.
  • Consuming animal protein harms health compared to plants.
2. What The Science Says
  • A 2025 systematic review of 30 RCTs found animal protein yields slightly greater muscle mass gains than plant protein overall, especially in younger adults (<60 years). However, no significant difference in muscle strength or physical performance was found.
  • Soy protein performs similarly to milk protein in supporting muscle mass.
  • Non-soy plant proteins (e.g., rice, oat, potato) are generally less effective than animal protein for muscle mass increase.
  • Another 2021 meta-analysis showed animal protein tends to increase lean mass more than plant protein, especially in younger adults, but effects vary and protein dose/adherence are key.
  • Epidemiological data suggest higher plant protein intake is associated with lower all-cause mortality and better chronic disease outcomes, while excessive red/processed meat intake may increase risk.
3. What Actually Matters
  • Total daily protein intake and adequate leucine content are critical for muscle protein synthesis, regardless of source.
  • Resistance exercise combined with sufficient protein supports muscle growth and maintenance.
  • Diverse plant protein sources including soy can be effective if total intake and amino acid needs are met.
  • For general health, plant-based diets rich in nuts, legumes, fruits, and vegetables are linked to lower chronic disease risk.
  • Animal proteins like fish and dairy provide high-quality protein and nutrients beneficial for muscle and overall health.
4. What This Means For You 
  • Aim for total protein intake suited to your goals (e.g., 1.2–2.0 g/kg/day for muscle gain).
  • Combine different plant proteins (soy, legumes, grains) to ensure a complete amino acid profile.
  • Include dairy, eggs, fish, or lean meats if you consume animal products for variety and quality.
  • Engage in regular resistance training for optimal muscle maintenance and growth.
  • For health, emphasize whole-food, minimally processed sources whether plant or animal.
  • Focus on sustainable, enjoyable eating patterns rather than strict exclusion.
5. Where Everything You Read Above Came From
  • Reid-McCann RJ, et al. Effect of Plant Versus Animal Protein on Muscle Mass and Physical Function: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutr Rev. 2025 Jul 1;83(7):e1581. 
  • Lim MT, Pan BJ, Toh DWK, et al. Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2021 Feb 18;13(2):661. 
  • Tang JE, et al. Protein Source and Muscle Growth: Comparative Analysis of Whey, Casein, Soy, and Plant Proteins. Am J Physiol Endocrinol Metab. 2009 Mar;296(3):E475-85. 
  • Haghighatdoost F, et al. Associations of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality: A Systematic Review and Meta-Analysis. Sci Rep. 2023 Feb 28;13(1):4104. 
  • Mobley CB, et al. Distinct Effects of Whey and Soy Protein Supplementation on Muscle Fiber Size: A Systematic Review. Int J Sport Nutr Exerc Metab. 2021 Jun;31(3):266-274.