Adolescence is a critical transitional period characterized by rapid and multifaceted changes in physical, psychological, and social dimensions. According to the World Health Organization, adolescence encompasses the age range of 10 to 19 years. Alongside physical changes, this period involves significant developments and transformations in knowledge, skills, and behaviors, driven by the individual's identity formation process. Health behaviors such as nutrition and physical activity play a pivotal role in protecting and promoting adolescent health. However, unhealthy eating habits and insufficient physical activity are highly prevalent among adolescents.

These behaviors are associated with physical problems, including obesity, diabetes, hypertension, cardiovascular diseases, delayed growth and development, and psychological issues such as susceptibility to stress, low self-esteem, and lack of confidence. Consequently, fostering healthy eating and physical activity behaviors in adolescents is essential.

Given that adolescents spend a considerable portion of their time in school, implementing school-based interventions to promote these behaviors represents an effective approach to preventing lifestyle-related health issues in adulthood. The literature indicates that various interventions aimed at improving nutrition and physical activity behaviors in adolescents are generally effective. Nevertheless, sustaining these behaviors in the long term remains a challenge, as studies have shown that increases in knowledge do not always translate into behavioral changes.

One of the most effective strategies for instilling healthy behaviors in adolescents is health education. School-based health education not only facilitates the acquisition of functional health literacy but also strengthens the attitudes, beliefs, and practical skills necessary for adopting and maintaining healthy behaviors. Moreover, health education is a powerful tool for enhancing health literacy components such as accessing, understanding, evaluating, and utilizing accurate health information, enabling adolescents to take responsibility for their health and make informed decisions.

This study aims to contribute to fostering healthy eating and physical activity behaviors in adolescents, supporting their transformation into lifelong habits. Additionally, the findings are expected to guide school health professionals, particularly school nurses, in expanding interventions within the scope of school health services.

Inclusion Criteria:

• - Volunteering to participate in the research
• Being allowed to participate in the study by their parents
• No physical or mental disabilities and chronic diseases (diabetes, metabolic syndrome, heart disease, etc.)

Exclusion Criteria:

• - Incomplete completion of research data collection forms
• Declining to participate in the research
• Failure to complete at least 5 health education sessions