Unhealthy dietary behaviors and associated factors among adolescents: a territory-wide study

Abstract Background Dietary behaviors during adolescence greatly influence lifelong health habits, with patterns and nutritional deficiencies at this stage potentially carrying into adulthood and affecting long-term health. This study examined associations between sociodemographic characteristics, health literacy, mental toughness, and unhealthy dietary behaviors among Hong Kong adolescents. Methods A cross-sectional survey was conducted between September and November 2024 with secondary school students (Grades 1–4) from 20 schools in Hong Kong. Participants completed a self-administered questionnaire assessing sociodemographic variables, socioeconomic status, dietary behaviors, physical activity, health literacy, and mental toughness. Descriptive analysis of the factors was conducted to illustrate the frequency and percentage distributions. Both crude prevalence and weighted prevalence of unhealthy dietary behaviors were calculated. An survey-weighted logistic regression model was employed to examine the factors associated with unhealthy dietary habits. Results A total of 1,423 secondary students were included in this study, comprising 802 females (56.4%) and 621 males (43.6%). The mean age of participants is 13.56 (standard deviation [SD]: ±1.39). Over half (51.0%) of adolescents skipped breakfast daily, while 86.1% and 83.8% reported inadequate vegetable and fruit consumption, respectively. In multivariable regression analysis, breakfast skipping was positively associated with excessive social media use (aOR = 1.668, 95% CI: 1.279–2.176, p < 0.001), and inversely related to sufficient sleep (aOR = 0.579, 95% CI: 0.447–0.751, p < 0.001), higher mental toughness(aOR = 0.692, 95% CI: 0.531–0.901, p = 0.006), and a higher level of health literacy(aOR = 0.659, 95% CI: 0.507–0.857, p = 0.002). Inadequate fruit intake was linked to older age groups (aORaged 13−14= 1.497, 95%CI: 1.035–2.166, p = 0.032; aORaged>14= 1.486, 95%CI:1.024–2.156, p = 0.037) and excessive screen time on game (aOR = 1.435, 95%CI:1.015–2.028,p = 0.041), while high socioeconomic status (aOR = 0.371, 95%CI: 0.213–0.643, p < 0.001) and higher level of health literacy (aOR = 0.674, 95% CI: 0.479–0.950, p = 0.024) reduced this risk. However, no significant association was found between factors and insufficient vegetable intake in the multivariable regression analysis. Conclusion Unhealthy dietary behaviors are widespread among Hong Kong adolescents and are associated with modifiable behavioral, psychological, and sociodemographic factors. Targeted multi-level interventions focusing on health literacy, physical activity, and screen time regulation are recommended.