When it comes to muscle gain, the first question that comes up is: “Do I need to eat meat to grow?”

For decades, animal protein was considered the gold standard of sports nutrition. Meat, eggs, and dairy products have always been praised for their high content of essential amino acids, especially leucine, a key player in activating muscle protein synthesis (MPS).

In contrast, vegan diets grew in popularity, driven by ethical, environmental, and health concerns. Still, doubts remained as to whether 100% plant-based protein would be sufficient for hypertrophy and lean muscle maintenance.

It was precisely to answer this question that researchers at the University of Illinois conducted a randomized, controlled clinical trial, published in 2025, investigating whether the origin of the protein (animal vs. vegetable) and the way it is distributed throughout the day influence the anabolic response in healthy young people who train resistance. The summary of this study can be found below:

🟠Participants:

• 40 young adults: 28 men and 12 women

• Average age: 25 years old.

• Average BMI: 24,1 kg/m².

• Everyone was physically active and healthy.

🟡Dietary Intervention

• Duration: 9 days.

• Daily protein: 1,1–1,2 g/kg (moderate amount, close to the recommendation for general health).

• Diet provided and monitored by researchers (less than 2% deviations).

• Four experimental groups:

❖ OMN-UB → Omnivorous with unbalanced protein (10% - 30% - 60% in 3 meals).

❖ OMN-B → Omnivorous with balanced protein (20% in 5 meals).

❖ VGN-UB → Unbalanced vegan.

❖ VGN-B → Balanced vegan.

🟢Training

• 3 supervised resistance training sessions throughout the study.

• Exercises for upper and lower limbs (leg press, leg extension, chest press, shoulder press, etc.).

• Intensity of 60% and 80% of 10RM (maximum load for 10 repetitions).

• Physical activity and energy expenditure were monitored with accelerometers.

🔵Measurements and Evaluations

• Muscle protein synthesis (MPS):

❖ Method: deuterated water (D₂O) + muscle biopsies (vastus lateralis, days 1 and 9).

❖ Monitoring the incorporation of amino acids into muscle proteins.

• Body composition:

❖ Assessed by DEXA (body composition by densitometry)

• Psychological well-being:

❖ Questionnaires on energy, calm, tension, anxiety, pleasure and fatigue (Feeling Scale, Felt Arousal Scale, State Anxiety Inventory, etc.).

🟣Results

1. Muscle protein synthesis

• There were no significant differences between vegans and omnivores.

• There was also no effect of protein distribution (balanced vs. unbalanced).

That is: with sufficient protein and training, the vegan diet is as effective as the omnivorous diet in stimulating muscle synthesis.

2. Strength and performance

• Similar evolution among the four groups.

3. Body composition

• Body mass and composition did not change significantly in either group.

4. Psychological well-being

• Omnivores reported a greater sense of pleasure with food.

• Vegans reported more energy and less fatigue during workouts.

• There were no relevant differences in calm, tension or anxiety.

🟤Conclusions

This study debunks one of the most persistent myths in sports nutrition... being vegan doesn't hinder muscle gain!!

• You don't need to eat meat to gain muscle. Beans, lentils, chickpeas, tofu, tempeh, seitan, soybeans, and combinations of grains and cereals offer complete proteins.

• Protein quality did not limit gains, as long as total intake was adequate.

• Protein distribution throughout the day was not decisive for short-term muscle synthesis.

• In addition to muscle, the vegan diet showed a subjective benefit in energy and vitality, while the omnivorous diet brought a greater feeling of pleasure with meals.

It's not meat that builds muscle, but the combination of adequate protein, training, and consistency.

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