Overweight among adolescents results from an energy imbalance between caloric intake and energy expenditure. The World Health Organization (WHO) has declared obesity a global epidemic, with approximately 28.5% of Indonesian adolescents reported to have excess body mass index (BMI). This study aimed to analyze the association between fast food consumption frequency, dietary fiber intake, sleep duration, and physical activity with the severity of excess weight status (overweight vs. obesity) among adolescents aged 16–18 years in Surakarta, Indonesia. This cross-sectional study involved 100 respondents with excess weight. Data were collected using a Food Frequency Questionnaire (FFQ), Semi-Quantitative Food Frequency Questionnaire (SQ-FFQ), Sleep Duration Questionnaire (STQ), and International Physical Activity Questionnaire (IPAQ), with nutritional status determined through anthropometric measurements. The FFQ and SQ-FFQ had been previously validated with a Pearson correlation coefficient r > 0.6 and reliability coefficient (Cronbach's alpha) > 0.7. The STQ was validated with r > 0.6 and Cronbach's alpha > 0.8, while the IPAQ has been internationally validated and widely used across studies. Nutritional status was determined through anthropometric measurements. Data analysis included chi-square tests and binary logistic regression. Of 100 respondents, 56% were classified as overweight and 44% as obese. Chi-square analysis revealed significant associations between fast food consumption frequency (p = 0.020), dietary fiber intake (p < 0.001), and sleep duration (p = 0.013) with the severity of excess weight status, while physical activity showed no significant association (p = 0.912). Binary logistic regression identified low dietary fiber intake as the most dominant risk factor (OR = 29.034; 95% CI = 6.216–135.605; p < 0.001), followed by low fast food consumption frequency (OR = 7.941; 95% CI = 1.447–43.579; p = 0.017). Low dietary fiber intake is the most dominant risk factor for the severity of excess weight status among adolescents.