Introduction: Dietary trends such as consumption of lactose-free and gluten-free products or the use of alternative slimming diets are gaining increasing popularity, especially among young people. They determine their dietary choices, which are important from the point of view of human health. Unconventional diets are still considered as effective weight loss methods. The use of alternative diets may cause shortages of an essential nutrients, increase the risk of chronic non-communicable diseases and lead to the formation of incorrect eating habits. Balanced diet, in contrast to the alternative diet, takes into account the principles of rational nutrition and nutritional recommendations of the Institute of Food and Nutrition (IŻŻ). The aim: To investigate the influence of popular dietary trends on nutrition of high school adolescences.Material and methods: Subjects were adolescences in the age of 17-21 years attending high schools in Ruda Slaska (262 students, including 157 women and 105 men). Self-constructed questionnaire was applied in the study. Participation in the study was anonymous and voluntary.Results: In more than a half of young women (54,8%) and men (52,4%) the body mass deficiency was revealed (BMI<18 kg/m2). 33,6% of the respondents were on the non-balanced diets at least once in their lives. High school students knew gluten-free and lactose-free products but dietary trends, such as the consumption of gluten-free and lactose-free products, did not affect their diet. The main source of nutritional knowledge among respondents were their friends (78,2%).Conclusions: The results of the conducted research indicate the need to implement educational programs on the principles of proper nutrition. The increasing awareness of the youth in this regard may contribute to reducing the interest in still popular alternative diets among young people and taking appropriate health behaviors by them.