Can you build muscle on a vegan diet?

Walk into any gym and you’ll overhear the same debate: Do you need meat to build muscle? For decades, conventional wisdom has said “yes.” After all, animal proteins, think chicken, eggs, beef, are considered “high quality” because they’re packed with essential amino acids that our muscles need. Plant proteins, on the other hand, have often been seen as second-class citizens in the protein world.

But a study from the University of Illinois Urbana–Champaign is challenging that old story. Published in Medicine & Science in Sports & Exercise, the research suggests that when it comes to building muscle after resistance training, vegan diets hold their own against meat-based diets. But there's more: how you spread your protein across the day, whether in three big meals or in smaller, evenly spaced portions, doesn’t seem to make much difference either.

Every time you eat protein, your body breaks it down into amino acids, the building blocks of muscle. After exercise, your muscles become especially eager to soak up those amino acids and use them to repair and grow stronger. Scientists call this process muscle protein synthesis, and it’s the foundation of strength training.

Animal proteins have long been the gold standard because they’re highly digestible and rich in leucine, an amino acid that acts like a starter pistol for muscle growth. Plant proteins are often lower in leucine and may be harder for the body to digest, leading to fears that vegan diets can’t keep up when it comes to muscle repair.

The Illinois research team, led by Dr. Nicholas Burd, a professor in the Department of Health and Kinesiology, decided to put this theory to the test under real-world conditions. The researchers recruited 40 healthy, active young men and women (28 men and 12 women, average age 25). None of them were full-time bodybuilders, but all had some experience with weight training. Participants were randomly assigned to one of four groups including Omnivorous, Unbalanced Protein (OMN-UB) on a meat-based diet, with most protein eaten at dinner; Omnivorous, Balanced Protein (OMN-B) eating a meat-based diet, with protein spread evenly across five meals; Vegan, Unbalanced Protein (VGN-UB), on a plant-based diet, with most protein eaten at dinner; and Vegan, Balanced Protein (VGN-B) eating a plant-based diet, with protein spread evenly across five meals.

For nine days, everyone ate carefully prepared meals provided by companies like Mom’s Meals (for the omnivores) and Mosaic Foods (for the vegans). Protein intake was set at about 1.1–1.2 grams per kilogram of body weight per day, slightly above the recommended daily allowance but not at the high levels often seen in bodybuilding circles.

Meanwhile, participants followed a resistance training program three days a week. Think squats, leg presses, chest presses, the bread-and-butter lifts you’d find in any gym. To measure muscle protein synthesis, the researchers used a clever trick: participants drank “heavy water” (water containing a harmless isotope of hydrogen) that allowed scientists to track how much new muscle protein their bodies were building each day.

So, what happened after the experiment?

Here’s the headline finding: there were no significant differences in muscle protein synthesis between the vegan and omnivorous groups. Omnivorous (unbalanced) had 3.04% protein synthesis per day whereas other groups had 2.43%, 2.52%, and 2.49% per day. In plain English: whether you got your protein from steak or soy, whether you ate it mostly at night or spaced throughout the day, your muscles responded about the same.

That’s a big deal, because it challenges the long-held belief that animal proteins are inherently superior for muscle growth, at least in young, healthy adults who are lifting weights.

Beyond the numbers, how did participants feel?

Interestingly, the study tracked how participants felt. Diet and exercise don’t just shape bodies; they shape moods too. People on omnivorous diets tended to report higher feelings of pleasantness after workouts, whereas people on vegan diets reported higher energy and less tiredness.

So while the muscle-building effects were similar, the psychological responses were a bit different. That’s worth noting, because enjoyment and well-being often determine whether someone sticks with an exercise program in the long run. For athletes, fitness enthusiasts, or anyone simply trying to live a healthier lifestyle, this study offers reassurance. You don’t need meat to build muscle: a well-planned vegan diet works just as well. Also, protein timing isn’t as critical as once thought. Spreading protein evenly across five meals didn’t outperform three bigger meals. Exercise itself is the big driver. Resistance training seems to amplify the muscle-building power of any adequate protein source. This doesn’t mean all proteins are created equal, plant proteins still vary in amino acid content and digestibility. But when eaten as part of a diverse diet, those differences appear less important than once feared.

This study adds to a growing body of research suggesting that plant-based diets can support athletic performance and recovery just as well as omnivorous diets. That’s good news not only for vegans but also for people concerned about sustainability and climate impact. Shifting to plant-based proteins is often recommended as a way to reduce greenhouse gas emissions and improve long-term health outcomes.

So, if you’re hitting the gym and considering a vegan diet, rest easy: your muscles won’t know the difference, as long as you’re getting enough protein overall. The message from science is simple: eat your protein, lift your weights, and your body will adapt, whether your fuel comes from beans or beef.

If you want to learn more, read the original article titled "Impact of vegan diets on resistance exercise-mediated myofibrillar protein synthesis in healthy young males and females: A randomized controlled trial" on Medicine & Science in Sports & Exercise at http://dx.doi.org/10.1249/MSS.0000000000003725.