Korean undergraduate students attempt to lose weight but often fail due to utilizing ineffective weight loss strategies. Some diet programs have succeeded, yet, they have not provided adequate skills for long-term weight maintenance. The aim of the study was to determine the effect of a low calorie diet and exercise with nutritional education on weight loss, serum lipid profiles, nutrient intakes, and dietary behavior modification in overweight and obese undergraduate students. The subjects in the low calorie diet group (LCD; n = 12) and the low calorie diet plus exercise group (LCDE; n = 13) had the same goal of losing 4 kg during a 12 week program. Nutrient intakes were assessed by the 24 hour recall method. Also, food habits and dietary behaviors were investigated by self-administered questionnaires before and after the weight control program and one month after completing the program. LCD and LCDE groups lowered body weight by 2 kg and 1 kg, respectively, although they decreased calorie intake by 355 and 287 kcal per day compared to intakes prior to the study. Body fat mass decreased in both the LCD and LCDE groups; however, the decrease was greater in the LCDE group. In addition, only the LCDE group increased muscle mass. The LCD group had a slightly better effect in reducing body weight, body fat, and waist circumference than the LCDE group. However, their decrease was reversed after the mid-study check in the LCD group; the reduction was better maintained and decreased more in the LCDE group. However, serum lipid profiles were already in borderline prior to the study; moreover, they were not modified after losing weight. The dietary behavior program helped students to develop better dietary habits. In conclusion, the combination of a low calorie diet and exercise is necessary in order to maintain longer weight loss by increasing muscle mass and decreasing body fat.