Background: Due to the increasing consumption of the internet, several outcomes are often seen among adolescents, including an increase in internet addiction (IA) and social media addiction (SMA). It could also have been associated with high body mass index (BMI) and eating disorders (EDs). This study aimed to assess the relationship between BMI, EDs, IA, and SMA among adolescents in Bangladesh and to determine the associated factors.

Methodology: Using a cross-sectional design, this study gathered data from adolescents aged 13-19 years old using an online questionnaire consisting of sociodemographic variables, BMI, eating disorder test scale (EAT-26), Young's Internet addiction test scale (IAT-20), and Bergen's social media addiction scale (BSMAS). Apart from the descriptive statistics and Pearson chi-square test, we employed two sets of binary logistic regression and bivariate co-relation matrix to analyze the data and to find out the relationship by SPSS 26.0.

Results: A total of 2147 adolescents with a mean age of 15.6 years old participated in the study; among them, 70.70% were female. Our study found that 23.2% of participants had EDs, 30.8% of students were addicted to the Internet, and 59.9% of participants were addicted to social media. Concerning BMI, we found that 6.6% of participants were underweight, 1.9% were overweight, 24% were obese, and the remaining 67.5% had a normal BMI. Gender, the purpose of the internet, daily internet use, physical exercise, the study of novels/stories, EDs, and BMI had a significant effect on increasing IA and SMA among adolescents. IA, SMA, and EDs were co-related.

Conclusion: The stakeholders should inspire and take necessary steps to engage the adolescents in physical exercise and literature habits to control the IA and SMA. And regarding BMI and EDs, the parents should be aware of this.