International students are experiencing health problems due to many lifestyle changes, such as those in dietary and sleep patterns. We conducted this study to identify the associations among sleep patterns, changes in eating habits after studying abroad, and overweight or obesity in international students. In this cross-sectional study, we analyzed data on health-related variables, changes in eating habits after studying abroad, and sleep patterns that were collected from 225 international students in South Korea. Approximately half of the participants experienced poor sleep (47.6%). After adjusting for covariates such as age, gender, nationality, and acculturative stress, the subjects who had poor sleep quality were 2.020-fold (adjusted odds ratio, 95% confidence interval = 1.045–3.906) more likely to be overweight and obese than those who had good sleep quality. There were significant differences in changes of eating habits after studying abroad according to sleep quality ( p < 0.001). When subjects were stratified into groups according to changes in eating habits after studying abroad, the risk of overweight and obesity increased in those with poor sleep quality but not in those with good sleep quality among subjects who had changes in bad eating habits. However, the risk of overweight and obesity did not differ among subjects with changes in good eating habits regardless of their sleep quality.