Vegans Can Build Muscle Just as Well as Meat-Eaters

Vegans can build muscle from weightlifting just as well as meat-eaters, according to new research.

Published in Medicine and Science in Sports and Exercise, the study involved 40 participants who were fed either a vegan or omnivorous diet and asked to complete 3 sessions of whole-body resistance training over 9 days.

Both groups had gained similar levels of muscle by the end of the trial.

The result surprised the researchers from the University of Illinois, given that previous studies have found that meaty meals help build muscle faster than vegan meals.

The Illinois team posits that the longer duration of their trial and the more substantial vegan meals they provided may have afforded the vegan participants the time and protein needed to “catch up” to their meat-eating counterparts. 

Vegan muscle building

Meat and muscle building often go hand-in-hand. Up until the recent rise of veganism in the Western world, few bodybuilders would have believed it possible to acquire the high levels of protein they need from a plant-based diet.

And the science, for the most part, backed them up.

Many studies have documented that animal-based protein foods facilitate a greater rise in muscle protein synthesis rates when compared to plant-derived protein sources, partly due to the lower digestibility of plant proteins.

However, a lot of these studies were comparing the effect of different protein sources (soy isolate and beef, for example) over a short period of time, sometimes following just one exercise session.

“The vast majority of previous research hasn’t necessarily compared meat to non-meat sources,” Andrew Askow, a PhD student at the University of Illinois and first author of the recent study, told Technology Networks.

“Rather, they have employed isolated sources of protein (whey vs soy isolates or similar comparisons) as a means to make these comparisons. Only relatively recently have investigators in the field made a concerted effort to make comparisons between whole-food sources of proteins.”

To determine whether a more substantial vegan diet, consumed over a longer period of time, might have a different effect on muscle growth, Askow and his colleagues recruited 40 participants, aged 20–40 years, who had experience with resistance training and weren’t already eating a vegan diet.

All participants underwent a “habituation week” when they consumed an omnivorous diet with an unbalanced protein distribution throughout the day to represent typical Western dietary patterns.

After reaching this baseline, the 40 individuals had a muscle biopsy to determine their initial integrated myofibrillar protein synthesis rates (levels of muscle building), were split into vegan and omnivorous groups and given meals for the next 9 days.

“In the omnivorous group, we focused on maximizing the amount of animal-derived protein via lean red meat, dairy, poultry, etc.,” Askow told Technology Networks.

“On the other hand, the vegan diet provided high-quality complementary proteins primarily from soy (tofu or tempeh), lentils, beans, nuts and grains. Given the higher food volume necessary to meet the energy and protein requirements from plant-derived foods, these meals were typically supplemented with higher-fat snacks to increase caloric intake without significantly increasing food volume.”

All participants returned to the assessment lab three times over the nine days for weight training exercises.

Each of the 40 participants gave a second, final muscle biopsy on the last day to determine how much their myofibrillar protein synthesis rates had increased following the intervention.

Surprisingly, both groups showed similar levels of muscle protein synthesis.

After some thought, the researchers say the unexpected protein power of their vegan diet may come down to its heft. After all, previous studies tend to have tested isolated vegan proteins against meat proteins after a single session of consumption.

“We posit that the lack of differences in our findings is likely attributable to a very discordant pattern in postprandial [post-meal] amino acid availability between isolated- and whole-food sources of protein,” said Askow.  

“That is, when isolated proteins are consumed, we observe a rapid and robust increase in plasma amino acid concentrations that return to baseline levels well before the next feeding occasions. In contrast, ingestion of whole-food mixed meals results in a much more subtle and prolonged increase in plasma amino acids that subsists past the typical five-hour period observed in most of these acute studies.”

However, Askow stresses that these findings were quite particular to the special vegan diet devised for the study, so any budding vegan bodybuilders should be equally specific with their protein intake.

“I think the biggest caveat, in my opinion,” he said, “is that the vegan diets we provided in our study were extensively well-planned and balanced in terms of complementary protein pairings to facilitate higher protein quality (i.e., digestibility and essential amino acid content).”

“While we demonstrated that plant-derived protein foods can be equally effective at supporting protein synthesis rates, it’s important to note that animal-derived protein foods are inherently better vehicles to deliver amino acids. Thus, consumption of a plant-based diet necessitates a bit more thoughtfulness in terms of food selection and planning. Nevertheless, as our paper noted, vegan approaches can be just as effective to support daily muscle protein synthetic rates.”

Reference: Askow AT, Barnes TM, Zupancic Z, et al. Impact of vegan diets on resistance exercise-mediated myofibrillar protein synthesis in healthy young males and females: A randomized controlled trial. Med & Sci Spor & Exer. 2025. doi: 10.1249/MSS.0000000000003725