Protein with resistance training on plant diets

Meta-analyses of randomised trials found that soy protein supports resistance-training gains in lean mass and strength much like animal protein, and that strength gains do not differ by protein source. Pooled trials show a small muscle-mass edge for animal protein over non-soy plant proteins, mostly in younger adults, while small training trials of high-protein vegan diets found comparable gains. Acute studies show plant proteins stimulate less muscle protein synthesis gram for gram; anabolic resistance in older adults is a separate topic.

Strength
Vegan

Evidence retrieved up to 15 October 2026

What the research shows

In healthy young adults doing resistance training with a high total protein intake, an exclusively plant-based diet supported gains in muscle mass and strength comparable to a protein-matched omnivorous diet.

Low certainty

Further research is likely to change this.

No known concerns at usual amountsNo clear effect

Who this is about

healthy young adults doing resistance training with a high protein intake

Practical note

Graded low: two small controlled trials (38 and 22 participants in the training phases), one non-randomised and retrospectively registered, both in young adults; downgraded for risk of bias and imprecision, as small trials cannot exclude modest differences. Trials raised protein to about 1.6 to 2 g per kg of body weight a day.

Vegan note

Both trials used vegan diets with protein raised to high levels (soy isolate in one, mycoprotein-rich foods in the other), so the result applies to well-planned, protein-rich vegan diets rather than to vegan diets in general.

Sources

Supports “is not different than a protein-matched mixed diet (mixed whole foods + whey protein supplementation) in supporting muscle strength and mass accrual” (Abstract, Conclusion) Hevia-Larraín V, Gualano B, Longobardi I, Gil S, Fernandes AL, Costa LAR, Pereira RMR, Artioli GG, Phillips SM, Roschel H. 2021. Sports Medicine. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
Supports “Resistance training increased lean mass in both groups by a similar magnitude” (Abstract, Results) Monteyne AJ, Coelho MOC, Murton AJ, Abdelrahman DR, Blackwell JR, Koscien CP, Knapp KM, Fulford J, Finnigan TJA, Dirks ML, Stephens FB, Wall BT. 2023. Journal of Nutrition. Vegan and Omnivorous High Protein Diets Support Comparable Daily Myofibrillar Protein Synthesis Rates and Skeletal Muscle Hypertrophy in Young Adults. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
Context “In younger individuals, these differences are largely attenuated when total protein intake is sufficient.” (Abstract, Results) Cannito T, Ivetac A, Fiotti N, Mearelli F, Di Bella S, Di Bella S, Girolamo FGD, Biolo G. 2026. Nutrients. Sustaining Muscle, Cardiovascular Health, and the Environment: Is Plant-Based Protein the Key? CC BY; credit Cannito et al., Nutrients 2026

In acute tracer studies, plant proteins gram for gram stimulate less muscle protein synthesis than animal proteins such as whey, which is linked to lower leucine content and digestibility; higher amounts and blends of plant proteins are discussed as ways to narrow the gap.

Low certainty

Further research is likely to change this.

No known concerns at usual amountsUnclear

Who this is about

adults in acute muscle protein synthesis studies

Practical note

Graded low: the finding comes from short-term tracer studies summarised in reviews, and acute muscle protein synthesis is an indirect marker that did not translate into consistent differences in long-term training trials (downgraded for indirectness). The 2026 review reports long-term studies with intakes of at least 1.0 to 1.2 g per kg a day.

Vegan note

This is why the trials showing comparable training gains on vegan diets used high total protein intakes.

Sources

Supports “Acute studies indicate that whey protein, likely related to its higher leucine content, stimulates muscle protein synthesis to a greater extent than proteins such as soy and casein.” (Abstract) Messina M, Lynch H, Dickinson JM, Reed KE. 2018. International Journal of Sport Nutrition and Exercise Metabolism. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
Supports “Acute tracer studies show that, gram-for-gram, animal-based proteins (particularly whey/dairy) stimulate greater myofibrillar protein synthesis due to higher leucine density, digestibility, and more rapid aminoacidemia” (Abstract, Results) Cannito T, Ivetac A, Fiotti N, Mearelli F, Di Bella S, Di Bella S, Girolamo FGD, Biolo G. 2026. Nutrients. Sustaining Muscle, Cardiovascular Health, and the Environment: Is Plant-Based Protein the Key? CC BY; credit Cannito et al., Nutrients 2026
Context “the anabolic potential of plant-based proteins can be enhanced through higher dosing, amino acid or leucine fortification, and complementary protein blending” (Abstract, Results) Cannito T, Ivetac A, Fiotti N, Mearelli F, Di Bella S, Di Bella S, Girolamo FGD, Biolo G. 2026. Nutrients. Sustaining Muscle, Cardiovascular Health, and the Environment: Is Plant-Based Protein the Key? CC BY; credit Cannito et al., Nutrients 2026

Pooled randomised trials found a small muscle-mass advantage for animal protein over plant protein, mainly against non-soy plant proteins and plant-based diets and mainly in younger adults.

Low certainty

Further research is likely to change this.

No known concerns at usual amountsUnclear

Who this is about

adults in randomised trials comparing plant and animal protein

Practical note

Graded low: meta-analyses of randomised trials, downgraded for imprecision (confidence limits close to zero; the non-soy comparison rests on 5 trials) and inconsistency (the 2021 review found no difference in absolute lean mass overall, and individual high-protein vegan training trials found none).

Vegan note

The gap was small and did not appear for soy; individual training trials of high-protein, well-planned vegan diets showed no difference.

Sources

Supports “Animal protein may have a small beneficial effect over non-soy plant protein for muscle mass” (Abstract, Conclusion) Reid-McCann RJ, Brennan SF, Ward NA, Logan D, McKinley MC, McEvoy CT. 2025. Nutrition Reviews. Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. CC BY; credit Reid-McCann et al., Nutrition Reviews 2025
Supports “younger adults (<50 years) were found to gain absolute and percent lean mass with animal protein intake” (Abstract) Lim MT, Pan BJ, Toh DWK, Sutanto CN, Kim JE. 2021. Nutrients. Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
Opposes “with no between-group differences for any of the variables (all p > 0.05).” (Abstract, Results) Hevia-Larraín V, Gualano B, Longobardi I, Gil S, Fernandes AL, Costa LAR, Pereira RMR, Artioli GG, Phillips SM, Roschel H. 2021. Sports Medicine. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

In adults doing resistance training, soy protein supplementation produced gains in lean mass and strength similar to whey, milk or other animal protein supplementation.

Moderate certainty

Further research may change the size of the effect.

No known concerns at usual amountsNo clear effect

Who this is about

adults doing resistance training

Practical note

Graded moderate: two meta-analyses of randomised trials (9 studies in 2018; 17 soy-versus-milk trials within a 43-trial 2025 review) agree; downgraded one level for imprecision from small trials and a possible conflict of interest in the 2018 review.

Vegan note

Soy is the plant protein with the most trial evidence and was the one that performed like animal protein in both meta-analyses.

Sources

Supports “There was no pooled effect difference between soy and milk protein for muscle mass (SMD = -0.02; 95% CI: -0.20, 0.16; P = .80) (n = 17 RCTs)” (Abstract, Conclusion) Reid-McCann RJ, Brennan SF, Ward NA, Logan D, McKinley MC, McEvoy CT. 2025. Nutrition Reviews. Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. CC BY; credit Reid-McCann et al., Nutrition Reviews 2025
Supports “The results of this meta-analysis indicate that soy protein supplementation produces similar gains in strength and LBM in response to RET as whey protein.” (Abstract) Messina M, Lynch H, Dickinson JM, Reed KE. 2018. International Journal of Sport Nutrition and Exercise Metabolism. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

Across randomised trials in adults, gains in muscle strength did not differ between plant and animal protein sources.

Moderate certainty

Further research may change the size of the effect.

No known concerns at usual amountsNo clear effect

Who this is about

adults in randomised protein-source trials, with or without resistance training

Practical note

Graded moderate: two meta-analyses of randomised trials agree (16 trials in 2021; 14 trials with strength outcomes in 2025); downgraded one level for imprecision and indirectness, since many trials compared supplements rather than whole diets.

Vegan note

Supports plant protein sources for strength outcomes; most trials tested soy.

Sources

Supports “No significant difference was found between plant or animal protein for muscle strength (n = 14 RCTs) or physical performance (n = 5 RCTs).” (Abstract, Conclusion) Reid-McCann RJ, Brennan SF, Ward NA, Logan D, McKinley MC, McEvoy CT. 2025. Nutrition Reviews. Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. CC BY; credit Reid-McCann et al., Nutrition Reviews 2025
Supports “Results from the meta-analyses demonstrated that protein source did not affect changes in absolute lean mass or muscle strength.” (Abstract) Lim MT, Pan BJ, Toh DWK, Sutanto CN, Kim JE. 2021. Nutrients. Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine