We surveyed 553 middle school students living in Incheon using questionnaires to compare their food behaviors and snack intake patterns according to weight groups based on BMI. Mean BMI was 20.3 for males and 19.6 for females. The rate of underweight, normalweight and overweight students was 33.3, 51.7, and 15.0%, respectively. Compared to the other two groups, the overweight students perceived their body shape more accurately (p<0.01). Regarding the reasons for skipping dinner, the most frequent answer by the underweight students was 'because of snacks', while that of the overweight students was 'to lose weight' (p<0.01). The normalweight students were found to eat a Korean traditional type breakfast more frequently than the other weight groups (p<0.05). The overweight female group was more likely to overeathabitually, whereas the normalweight and underweight groups tended to overeat when they were under stress (p<0.05). As for the amount of the snack intake, the overweight male students replied that they eat quite a lot of snacks. As a conclusion, the problems found in the underweight group were unbalanced diet and the disturbance of regular meal patterns due to inappropriate snack intake. The problems shown in the overweight group were overeating due to habit or stress, fast eating speed and large amount of snack intake.