A vegan diet for the athlete: how to cover your protein

A plant-based diet and strength sports stopped being incompatible long ago, but the protein part of a vegan menu requires more precise calculation than for an omnivorous athlete. The editorial team broke down how much protein you need, why leucine matters, which foods actually work and where the typical mistakes are hidden.

Can a vegan build muscle

The question the editorial team receives most often: is it really possible to build muscle mass without meat, fish, eggs and dairy? The short answer is yes, but with one condition: a plant-based diet requires more careful planning of the protein part. The mere fact of giving up animal products does not block hypertrophy; problems arise when a person simply removes meat from the plate and replaces it with nothing.

The most convincing argument came from a study by Hevia-Larraín and colleagues (2021). Habitual vegans and omnivorous young men followed the same strength program for 12 weeks and consumed roughly the same amount of protein — about 1.6 g per kilogram of body weight, with the vegans meeting it through soy isolate. The gains in muscle mass and strength did not differ significantly between the groups.

At the same time, in other work where plant protein was given in small single servings, the anabolic response of the muscles was weaker than to an equivalent amount of whey or milk. The review by van Vliet, Burd and van Loon (2015) explains this by three factors: lower digestibility, a smaller content of essential amino acids (especially leucine) and a deficit of individual amino acids, such as lysine or methionine.

So the task of a vegan athlete is not to “prove” that plants are worse or better, but to compensate for these three differences through quantity, the combination of sources and the choice of concentrated foods. That is exactly what this article is about: how to calculate the requirement, what to build it from and where mistakes are made most often.

How much protein you need and why a vegan needs a little more

For people who regularly do strength training, the position of the International Society of Sports Nutrition (ISSN, 2017) defines a range of 1.4–2.0 g of protein per kilogram of body weight per day. A meta-analysis by Morton and colleagues (2018) showed that the additional benefit for gains in lean mass on average stops increasing at about 1.6 g/kg, although the upper bound of the confidence interval reached roughly 2.2 g/kg.

For a vegan the editorial team advises aiming at the upper half of the range — 1.8–2.0 g/kg, and during a calorie deficit even a little higher. The logic is simple: the digestibility of part of the plant protein is lower because of fiber and antinutrients (phytates, trypsin inhibitors), so the “net” protein from the same number of grams on the label comes out lower.

In practice this means that an athlete weighing 80 kg should plan for roughly 145–160 g of protein per day. It sounds like a lot, but across five meals that is 30–35 g per meal — entirely achievable if each contains a concentrated source: tofu, tempeh, seitan, legumes or protein powder.

What matters is not only how much, but also how the protein is distributed. Studies with animal proteins show that an even distribution across 3–5 meals is more effective than one large meal in the evening. For plant sources this principle is all the more relevant, because each serving has to “reach” the leucine threshold.

• daily target: 1.8–2.0 g/kg (in a deficit — closer to the upper limit);
• number of protein meals: 4–5;
• benchmark per meal: 0.4–0.5 g/kg or 30–40 g of plant protein;
• mandatory — a protein meal within a few hours after training.

Leucine and the amino acid profile

Leucine is a branched-chain amino acid that acts as a signal to trigger muscle protein synthesis through the mTORC1 complex. In studies with animal proteins the anabolic effect was maximized when a single serving contained roughly 2–3 g of leucine. For whey that corresponds to 20–25 g of protein, while for most plant isolates a somewhat larger serving is needed.

Gorissen and colleagues (2018) analyzed the amino acid composition of commercial plant isolates. It turned out that the share of essential amino acids in many of them is lower than in animal proteins, and leucine is noticeably lower than in whey. The exception was corn protein with a high leucine content, but it is poor in lysine.

Hence the practical rule: a plant serving should be increased by 20–40% compared with an animal one to obtain the same amount of leucine. The second rule is to combine sources. Legumes are rich in lysine but poor in methionine; grains are the opposite. Combining peas and rice in one powder, or lentils with wholegrain bread in one dish, evens out the profile.

The old myth that a “complete protein” must be assembled within a single plate is not supported by science: the body’s amino acid pool is replenished over the course of the day. However, for an athlete who wants to maximize the response to a specific workout, combining within a meal does make sense.

Some vegans additionally use leucine or EAA supplements of plant origin (produced by fermentation). This is an acceptable tool, but it does not replace full protein food, because building muscle requires all the essential amino acids, not just the signaling one.

Sources of plant protein: what actually works

Not all foods that are called “protein” are equally useful for gaining mass. Nuts and seeds contain a decent amount of protein, but along with it — a lot of fat and calories, so covering 150 g of protein with them without an energy surplus is difficult. The foundation should be foods with high protein density, that is, with a large share of protein per 100 kcal.

Soy holds a special place: its protein has a PDCAAS score close to animal proteins, and it was exactly soy isolate that was used in the Hevia-Larraín study. Concerns about “female hormones” in soy for men at normal dietary intake are not supported by clinical data.

Protein powders for a vegan are not a luxury but a convenient tool. Blends of pea and rice protein even out the amino acid profile, and one serving covers 20–25 g of protein without excess fiber. This is especially important for those who get bloating from large amounts of legumes.

During the processing of legumes, part of the antinutrients can be reduced: soaking, long cooking, sprouting and fermentation increase the digestibility of protein and minerals. Tempeh and miso are more advantageous from this point of view than raw or undercooked beans.

Micronutrients and common mistakes

Protein is not the only vulnerable link in a vegan athlete’s diet. The position of the Academy of Nutrition and Dietetics of the USA (Melina et al., 2016) recognizes well-planned vegan diets as adequate for all stages of life and for athletes, but emphasizes several nutrients that need attention.

• Vitamin B12— practically absent in plants; a supplement or fortified foods are mandatory.
• Iron— non-heme iron is absorbed worse; vitamin C in the same meal helps.
• Zinc and iodine— worth monitoring, especially with intense sweating.
• Calcium and vitamin D— important for bones; in vegans they are often reduced.
• Omega-3 (EPA/DHA)— a possible source: microalgae oil.
• Creatine— vegans have lower stores in the muscles, so the response to a supplement may be more pronounced.

Rogerson (2017), in a practical review for vegan athletes, separately draws attention to the risk of insufficient calorie intake. Plant food is bulky and filling, so an athlete with high energy expenditure may physically fail to eat the required amount. An energy deficit, in turn, nullifies any effort with protein.

The most common mistake the editorial team sees is “vegetarianism on pasta and bread”: lots of carbohydrates, little concentrated protein, and then disappointment in the progress. The second mistake is excessive reliance on nuts and nut butters, which provide calories but not protein density.

The third mistake is ignoring blood tests. People who have long eaten without animal products should check their B12, ferritin and vitamin D levels at least once a year, and if there are problems with recovery, discuss the results with a doctor.

Editorial conclusions

A vegan diet is compatible with gaining muscle mass if the total amount of protein is sufficient and each meal contains a concentrated source. Data from randomized studies show that with an equalized amount of protein the results of vegans and omnivores can be comparable.

Practical benchmarks: 1.8–2.0 g of protein per kilogram, 4–5 meals, servings 20–40% larger than for animal protein, and a combination of legumes with grains or ready-made blends of pea and rice isolates. Soy remains one of the most valuable plant sources.

One should not forget about B12, iron, zinc, iodine, omega-3 and creatine — these nutrients often matter for the result no less than the grams of protein.

Next we recommend reading our materials on choosing a protein powder, on creatine for beginners and on distributing protein throughout the day.

References

1. Hevia-Larraín V, Gualano B, Longobardi I, et al. High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: a comparison between habitual vegans and omnivores. Sports Med. 2021;51(6):1317–1330.
2. van Vliet S, Burd NA, van Loon LJC. The skeletal muscle anabolic response to plant- versus animal-based protein consumption. J Nutr. 2015;145(9):1981–1991.
3. Gorissen SHM, Crombag JJR, Senden JMG, et al. Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids. 2018;50(12):1685–1695.
4. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
5. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384.
6. Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: vegetarian diets. J Acad Nutr Diet. 2016;116(12):1970–1980.
7. Rogerson D. Vegan diets: practical advice for athletes and exercisers. J Int Soc Sports Nutr. 2017;14:36.