BACKGROUND: Low nutrition literacy (NL) among adolescents can worsen health and economic inequalities, potentially leading to a higher burden of non-communicable diseases. AIM: This study aimed to assess Total Nutrition Literacy (TNL) and its domains across different adolescent stages with an in-depth look at NL among Egyptian adolescents, through a quartile-based approach. It analysed the relation between adequate NL influences and vitamin, mineral intakes and body mass index (BMI) categories (underweight, normal, overweight/obese). It explored the effects of adolescent characteristics (gender, BMI) and family environment (parental education, food literacy, health status) on achieving adequate TNL levels. METHODS: A cross-sectional study was conducted with 1,050 Egyptian adolescents aged 10-19 from various geographical and socioeconomic backgrounds. Data were collected using a self-administered questionnaire measuring demographic information, TNL and its domains (categories) (Functional (FNL), Interactive (INL), and Critical (CNL)), and parental food literacy (PFL). Anthropometric measurements assessed nutritional status via BMI. Statistical analyses using SPSS identified associations and predictors of adequate TNL. RESULTS: TNL scores rose significantly from 68.8 in early adolescence (10-13 years) to 77.4 in late adolescence (17-19 years) (p < 0.001). All domains improved with age (p < 0.001), with females outperforming males in INL and CNL (p < 0.001). FNL level was notably low at 56.6%, compared to higher rates in INL (84.1%) and CNL (91.0%). Meanwhile, the median scores for NL remain relatively close to the lower levels of adequacy across all stages. Parental employment, PFL, health status, and family dynamics were significant predictors of adequate TNL. Maternal education became particularly crucial in late adolescence, while PFL had the greatest influence in early and middle adolescence. Adequate TNL increased the likelihood of reporting vitamin intake by nearly five times (COR = 4.9, p < 0.01). The relation between TNL and its domains with BMI vary across adolescence. CONCLUSION: Using quartile distribution to assess literacy adequacy provided a detailed view of literacy gaps, allowing identification of adolescents most in need of intervention. NL programs have to be tailored to meet adolescents' evolving needs, emphasizing foundational literacy in early adolescence, interactive skills in middle adolescence, and critical literacy in late adolescence.