Vegetarian and vegan diets are becoming more and more popular. Vegetarianism is a diet that eliminates all kinds of meat from the diet, including poultry, fish and seafood. Vegans give up on eating not only meat, but also other products of animal origin, the production of which is associated with the exploitation of animals, such as: dairy products (including eggs) and honey. It is not only a diet, but above all a lifestyle that includes many aspects such as not using cosmetics or buying clothes made of animal raw materials, not participating in entertainment in which animals are used. A vegan diet should be properly balanced, because people using it are more likely to be deficient in vitamin B12, iron, and calcium. The effect of a vegan diet on the growth of muscle mass in athletes, including bodybuilders, has also been observed. The aim of the study was to determine the effect of a vegan diet on the results achieved in body sports and to compare this information with non-vegan diets. The work is illustrative. The article is based on a review of the current literature available in the PubMed database, information and research from the Internet and documentary programs.