Prevalence of overweight and obesity and their associations with lifestyle habits among late adolescents in the Northern Border Region of Saudi Arabia: a cross‑sectional study

BACKGROUND: Adolescent obesity is a growing public health problem worldwide, and Saudi data show a high and rising burden of excess weight among youth with marked regional and gender disparities. Late adolescence is a critical window in which lifestyle behaviours consolidate and track into adulthood. AIM: To estimate the prevalence of overweight and obesity (primary outcome) and to examine their associations with lifestyle habits, including physical activity, sedentary behaviour, sleep, and dietary patterns (secondary outcomes), among late adolescents in the Northern Border Region of Saudi Arabia. METHODS: A cross‑sectional study was conducted among 352 late adolescents (18-21 years) enrolled in high schools and universities in the Northern Border Region, selected from a finite population of 51,461 using Cochran's formula. Body mass index (BMI) was calculated from self‑reported weight/height, and classified according to WHO cut‑offs. Lifestyle habits were assessed using the validated Arab Teens Lifestyle (ATLS) questionnaire, which covers sociodemographic characteristics, physical activity, sedentary behaviour, sleep, and dietary habits. Associations between BMI categories and covariates were examined using Pearson's Chi-square tests and t‑tests/ANOVA, and multiple linear regression was used to identify factors independently associated with BMI. RESULTS: Among participants, 54.1% of those aged 18 years or younger were overweight, while 68.8% of those >18 years were obese (p =0.004). Males predominated in the overweight group (72.1%), whereas females accounted for most obese participants (59.7%; p <0.001). Lower family income (5,000 to less than 10,000 SAR) was associated with overweight (73.8%) and obesity (57.1%; p < 0.001). High screen time (>2 hours/day) was reported by 82.8% of overweight adolescents (p <0.001). High consumption of sugary and energy drinks was associated with higher BMI, whereas frequent fruit and vegetable intake was associated with significantly lower BMI (all p <0.001). In multivariable analysis, total physical activity was independently associated with lower BMI (B = -0.16, p<0.001), whereas a higher composite dietary score was modestly positively associated with BMI (B = 0.12, p<0.001). CONCLUSION: Overweight and obesity are common among late adolescents in the Saudi Northern Border Region and are closely linked to sociodemographic, behavioural, and dietary factors. Physical activity emerged as the key modifiable protective factor. In contrast, high screen time and frequent consumption of sugary drinks were associated with higher BMI, underscoring the need for targeted changes in food environments and opportunities for safe physical activity.