The Claim

In healthy young men aged 26 years on average, consuming a high-protein (1.6 g/kg/day) exclusively plant-based diet supplemented with soy protein isolate for 12 weeks during supervised resistance training produces equivalent increases in leg lean mass, muscle fiber cross-sectional area, and leg-press strength as a protein-matched omnivorous diet supplemented with whey protein.

Source: High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
60score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

In healthy young men undergoing supervised resistance training, a plant-based diet with soy protein provides the same increases in leg muscle size and strength as an omnivorous diet with whey protein, when both provide the same total amount of protein per day.

See the scientific wording

In healthy young men aged 26 years on average, consuming a high-protein (1.6 g/kg/day) exclusively plant-based diet supplemented with soy protein isolate for 12 weeks during supervised resistance training produces equivalent increases in leg lean mass, muscle fiber cross-sectional area, and leg-press strength as a protein-matched omnivorous diet supplemented with whey protein, indicating that protein source does not limit muscle adaptation when total protein intake is adequate.

Why this might work

When a person eats enough protein from any source and lifts weights, the amino acids from the protein enter muscle cells and turn on a molecular switch that tells the cell to build more muscle fibers. This causes the muscle fibers to get thicker over time, increasing muscle size and strength.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores

    When young men lift weights and eat enough protein—whether from soy and plants or from whey and meat—they build the same amount of muscle and strength. The study proved it by comparing both diets and finding no difference.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.