Increasing the adaptive capacity of professional athletes depends on proper nutrition, especially in training and competitions' period. In this regard, it is relevant to study the actual nutrition and assess its compliance with the energy expenditure of athletes. The aim - to study the actual nutrition and energy expenditure of athletes from male water polo national team of the Russian Federation in the competitive period. Material and methods. In March 2018, 15 highly skilled sportsmen-men engaged in water polo were examined; qualification - 11 masters of sports, 4 candidates for the master of sports; Slavic ethnos. The average age was 23.1±0.6 years. The actual nutrition was studied by a 24-hour food record method and by the frequency method. The anthropometric examination was carried out according to a unified method using standard medical scales, a medical height meter and a rubberized measuring tape. Measurement of energy expenditure and heart rate at rest and under load was performed on a bicycle ergometer using an wireless ergospirometer and a chest pulse meter. Results and discussion. The determination of daily energy expenditure in athletes of the men's Russian national water polo team showed that the average value was 4350±129 kcal. А peculiar feature of the diet of water polo players is its high caloric value (5165±539 kcal/day), caused by energy expenditure during physical exertion and additional thermogenesis in conditions of long training in water. Excessive (1.5 times in comparison with the recommended values) consumption of fats, including saturated fatty acids by 1.3 times, added sugar and added salt is a risk factor of cardiovascular diseases, diseases of digestive organs, endocrine system, including type 2 diabetes. Low values of consumption of vegetables and fruits, dairy products, fish products and high levels of sugar and confectionery have been established. Conclusion. The imbalance of diets on two basic nutrients (fats, carbohydrates) has been revealed. The data obtained were the basis for the formation of individual recommendations on nutrition for each athlete, taking into account athletes' metabolic parameters and the level of physical activity. It is necessary to continue studies of anthropometric indices in dynamics for the most adequate assessment of the compliance of actual nutrition with energy consumption, and further correction of the diet in order to improve athletes' performance. Copyright© GEOTAR-Media Publishing Group.