A Vegan Diet for an Athlete: How to Cover Protein

A plant-based diet and strength sport long ago ceased to be incompatible, but the protein part of a vegan’s menu requires a more precise calculation than for an omnivorous athlete. The editorial team examined how much protein is needed, why leucine is important, which products really work, and where the typical mistakes are hidden.

Can a vegan build muscle

The question the editorial team receives most often: is it realistic to build muscle mass without meat, fish, eggs, and dairy products? The short answer is yes, but with one condition: a plant-based diet requires more careful planning of the protein part. The very 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 was the study by Hevia-Larraín and co-authors (2021). Habitual vegans and omnivorous young men performed the same strength program for 12 weeks and consumed approximately the same amount of protein — about 1.6 g per kilogram of body weight, with the vegans making it up with soy isolate. The gain in muscle mass and strength did not differ substantially between the groups.

At the same time, in other works, 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 lower 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 by quantity, a combination of sources, and the choice of concentrated products. This is exactly what the article is devoted to: how to calculate the requirement, what to compose it from, and where people most often make mistakes.

How much protein is needed and why a vegan needs a bit more

For people who regularly perform 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. The meta-analysis by Morton and co-authors (2018) showed that the additional benefit for the gain of lean mass on average stops increasing at about the level of 1.6 g/kg, although the upper bound of the confidence interval reached about 2.2 g/kg.

For a vegan, the editorial team advises being guided by the upper half of the range — 1.8–2.0 g/kg, and in a period of calorie deficit even a bit 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 to less.

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

It matters not only how much but also how the protein is distributed. Studies with animal proteins show that an even distribution over 3–5 meals is more effective than one large intake in the evening. For plant sources this principle is all the more relevant, because each serving must «reach» the leucine threshold.

• target per day: 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 intake within a few hours after training.

Leucine and the amino acid profile

Leucine is a branched-chain amino acid that works 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 approximately 2–3 g of leucine. For whey this corresponds to 20–25 g of protein, while for most plant isolates a somewhat larger serving is needed.

Gorissen and co-authors (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 there is noticeably less leucine than in whey. The exception was corn protein with a high leucine content, but it is poor in lysine.

Hence a practical rule: a plant serving should be increased by 20–40% compared with an animal one in order to get 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 whole-grain bread in one dish, evens out the profile.

The old myth that a «complete protein» must be assembled within one plate is not confirmed 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 plant-derived EAA supplements (of fermentation synthesis). 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 really works

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

Soy occupies a special place: its protein has a PDCAAS coefficient close to that of animal proteins, and it was soy isolate that was used in the Hevia-Larraín study. Concerns about «female hormones» in soy for men at ordinary dietary consumption are not confirmed 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 closes 20–25 g of protein without excess fiber. This is especially important for those in whom large volumes of legumes cause bloating.

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

Micronutrients and typical 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 US (Melina et al., 2016) recognizes well-planned vegan diets as adequate for all stages of life and for athletes, but emphasizes several nutrients that require 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 the bones, often reduced in vegans.
• Omega-3 (EPA/DHA)— a possible source: microalgae oil.
• Creatine— vegans have lower reserves 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 caloric intake. Plant food is bulky and filling, so an athlete with high energy expenditure may physically not eat the required amount. An energy deficit, in turn, nullifies any efforts with protein.

The most frequent mistake the editorial team sees is «vegetarianism on pasta and bread»: a lot of carbohydrates, little concentrated protein, and then disappointment in progress. The second mistake is an excessive reliance on nuts and nut butters, which gives calories but not protein density.

The third mistake is ignoring tests. People who have long eaten without animal products should check their B12, ferritin, and vitamin D levels at least once a year, and in case of recovery problems — 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 protein grams.

Next we recommend reading our articles on choosing a protein powder, on creatine for beginners, and on the distribution of 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.