Fast-food consumption behaviours are increasing among children and youth. In particular, unhealthy eating habits are more prevalent among university students in Sri Lanka. Such habits are often associated with adverse impacts on nutrition and health. Therefore, the present study was conducted to identify the fastfood intake habits of undergraduates at state universities in Sri Lanka and determine the relationship between fast-food habits and Body Mass Index (BMI). Data regarding the level of fast-food consumption, time duration for consuming fast food on a daily, weekly and monthly basis, height, weight and other factors associated with choosing fast food were obtained through a self-administered questionnaire distributed among undergraduates (N = 250). Descriptive and inferential statistical techniques were applied in this study. According to the findings, 32.3% of the sample's BMI indicated overweight (26 ? 30 kgM2). Participants' overall fast-food consumption habits were 15.29% for males and 65.21% for females, respectively. 30.3% of the participants consumed fast-food 2 to 3 times a week. Compared with other factors, the university environment contributed 54.3% to selecting such food, representing an increased influence. A positive significant relationship (p<0.05) was observed between fast-food consumption and an increase in BMI. In summary, the behaviour of students' fast-food consumption has significantly increased. The findings of this study can be utilised to design interventions to reduce fast-food consumption among students. Additionally, researchers can develop strategies to encourage healthier eating habits among students. Finally, this study can inform policies to create an environment that promotes healthy eating habits.