Understanding the Gap Between Nutritional Knowledge and Dietary Behavior Among Adolescents with Different BMI...

Background/Objectives: The aim of this study was to examine the discrepancy between nutrition-related knowledge (NRK) and nutrition-related practice (NRP) among 1440 Polish school-aged students (10-18 years), according to BMI status, and to identify factors associated with this discrepancy. Methods: This cross-sectional study was conducted via the CAWI method using an author-developed, non-validated questionnaire. Questions assessing NRK and NRP were thematically aligned and referred to the recommendations of the Polish Healthy Eating and Lifestyle Pyramid for Children and Adolescents (aged 4-18 years). Results: Students with excess weight scored significantly lower in nutritional knowledge (NRK: 46%) and practices (NRP: 30%) than those with underweight or normal weight (NRK: 52-53%, NRP: 33-34%). Higher NRK was associated with older age, female sex, larger urban residence (for students with overweight and obesity), and higher maternal/legal guardian education level (for students with normal/underweight body weight). Better NRP was associated with higher NRK and higher physical activity, while rural or small-town living was positively associated with healthier dietary practices and maintenance of normal BMI. Conclusions: The present study confirms that nutritional knowledge is a necessary but insufficient condition for shaping appropriate dietary behaviors among adolescents with different BMI statuses; lifestyle factors, practical food-related skills-including self-assessment of knowledge and adherence to dietary recommendations-and the broader environmental context plays a crucial role. These findings highlight the need for targeted nutrition education programs that expand not only knowledge but also practical skills among students.