Abstract
Background Overweight and obesity among adolescents have emerged as major public health concerns, particularly in urban India, due to rapid lifestyle transitions, unhealthy dietary practices, and increased sedentary behavior. Adolescence is a critical period during which excess weight often tracks into adulthood, increasing the risk of non-communicable diseases. However, city-specific data from metropolitan areas such as Chennai remain limited. Methods A school-based cross-sectional study was conducted from January 2025 to April 2025 among 222 adolescents aged 13-18 years in Chennai, Tamil Nadu. Data on socio-demographic characteristics and lifestyle behaviors were collected using a pre-tested structured questionnaire. Anthropometric measurements were recorded using standard procedures, and body mass index (BMI) was calculated and classified according to WHO BMI-for-age Z-scores (5-19 years). Associations were assessed using chi-square tests and odds ratios with 95% confidence intervals, followed by multivariate logistic regression to identify independent predictors. Results A total of 222 adolescents were included in the study. The overall prevalence of overweight and obesity was 21.7%, with 7.7% classified as overweight and 14.0% as obese. Female adolescents had significantly higher odds of being overweight or obese compared to male adolescents (OR = 6.11; 95% CI: 2.40-15.60). Excess daily screen time (>2 hours/day), frequent fast-food consumption (≥3 times/week), and late dinner timing (after 9 PM) were significantly associated with excess body weight on bivariate analysis. On multivariate analysis, female gender (AOR = 6.52), increased screen exposure (AOR = 2.46), and frequent fast-food intake (AOR = 2.58) remained independent predictors of overweight and obesity. Conclusions More than one-fifth of adolescents in this urban Chennai school were overweight or obese, highlighting a substantial and growing public health concern. Modifiable lifestyle factors, particularly screen exposure and fast-food consumption, play a significant role. Strengthening school-based and family-centered interventions focusing on healthy eating habits, physical activity, and reduced sedentary behavior is essential to address adolescent overweight and obesity and support long-term health and well-being.