The Study
High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores
This study watched two groups of young men — some who usually eat only plants and others who eat meat — while they lifted weights for 12 weeks. Both groups ate the same amount of protein. It found both groups gained about the same amount of muscle and strength. But because people weren’t randomly assigned to diets, we can’t say for sure the diet caused the results — other differences between the groups might have played a role.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
This study asked if young men can gain muscle just as well on a plant-based diet with soy as on a diet with meat and whey protein, when both get the same amount of protein and do the same workouts.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 560 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes, the result is meaningful—men on a fully plant-based diet built muscle just as well as those eating animal products, as long as they ate enough protein (1.6g/kg/day).
- 2Both groups gained about 1.2 kg of leg muscle and improved leg-press strength by at least 97 kg after 12 weeks.
- 3Muscle fibers got bigger in both groups, no matter if they ate plants or meat.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Sports Medicine
Year
2021
Authors
Victoria Hevia-Larraín, B. Gualano, Igor Longobardi, Saulo Gil, Alan L. Fernandes, L. Costa, R. Pereira, G. Artioli, Stuart M Phillips, H. Roschel
Related Content
Claims (4)
If you eat the same amount of protein and lift weights the same way, it doesn’t matter whether your protein is fast- or slow-digesting—even if it’s from plants like soy—your muscle gains will be about the same.
If young guys who don’t work out much eat a plant-based or meat-based diet with the same amount of protein and lift weights for 12 weeks, they’ll gain about the same amount of leg muscle and strength.
If you're a vegan or meat-eater and both of you lift weights and eat the same amount of protein every day, your muscles will grow just as much over three months — it doesn't matter where your protein comes from.
If young guys who don't usually lift weights eat about 1.6 grams of protein per kilo of body weight every day—whether from plant-based foods and soy protein or from regular mixed diets with whey—they can get noticeably stronger in their legs after 12 weeks of weight training.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.