Dietary Habits and Nutritional Knowledge of Adolescents in Lower Silesia (Poland): A Comparative Study Between 2011 and 2023

Background: Adolescence is a critical developmental period during which dietary habits are formed and may influence long-term health outcomes. Monitoring changes in adolescents’ eating behaviors and nutrition-related knowledge over time is important for developing effective health promotion strategies. The aim of this study was to compare adolescents’ (Lower Silesia, Poland) dietary habits and nutritional knowledge between two study periods (2011 and 2023) using comparable survey methods. Methods: A repeated cross-sectional comparison of two independent cohorts was conducted using an identical questionnaire in both study periods. The 2023 cohort included 14-year-old primary school students (n = 100; 48 girls and 52 boys), while the comparison group consisted of adolescents aged 13–15 years assessed in 2011 (n = 377; 202 girls and 175 boys). Anthropometric measurements and self-reported data on dietary habits and nutritional knowledge were analyzed using descriptive statistics and group comparison tests. Results: The findings indicate changes in selected dietary behaviors and levels of nutritional knowledge among adolescents over the studied period. A higher percentage of students in 2023 reported eating four meals per day and obtaining information about healthy eating from the Internet rather than from television. Students in 2023 were also more likely to recognize the relationship between diet and attention, identify the harmful effects of energy drinks and excessive fast-food consumption, and provide correct answers regarding proper nutrition. Nutritional knowledge improved over time, with a mean percentage of correct responses of 71.9% in 2023 compared with 63.7% in 2011. Although nutritional awareness improved in several areas, certain unhealthy eating habits remained prevalent, including irregular breakfast consumption and frequent intake of sweets. Changes in the distribution of body weight categories were also observed, with gender-specific differences between cohorts. Conclusions: The results suggest that improvements in nutritional knowledge alone may not be sufficient to ensure positive changes in dietary behavior among adolescents. Continued monitoring of adolescent nutrition and the development of comprehensive health promotion strategies addressing both knowledge and environmental influences remain necessary.