2011 Korea National Health and Nutrition Examination Survey showed that women in their twenties are most physically inactive among adult women. Therefore this study was done to investigate the physical activity pattern, average activity coefficient and energy expenditure of female university students who are in 20s. In addition, the association of body composition with physical activity level(PAL) was assessed. The correlations among three different methods used in measuring basal metabolic rate and total energy expenditure were also examined. One-day activity diaries were collected from 95 female university students in Seoul. Body composition was measured by Inbody 720. In some cases, subjects were divided into 3 groups according to either PAL or BMI. All data was analyzed by SPSS

The results of this study were as follows.
1. Female university students who participated in this study spent 428.3 minutes(min) on sleeping, 103.3 min on refinements such as reading, writing, watching TV, and internet surfing, 391.1 min on studying, 118 min on commuting, 34.4 min on walking slowly, 26.4 min on walking quickly, and 16.6 min jogging. If those are categorized with four levels according to the intensity of activity, they consumed 1139.7 min for weakest activity, 243.6 min for weaker activity, 26.8 min for normal activity, and 16.6 min for strong activity. The average activity coefficient of these female college students was 1.61

2. The comparison of body composition of female university students according to PAL showed that body weight, body fat mass, arm circumference and arm muscle circumference of physically active group were significantly higher than those of sedentary group.

3. Basal metabolic rate calculated by Harris-Benedict(H-B) formula, DRI formula, and Inbody value was 1375kcal, 1306kcal and 1209 kcal, respectively. The Pearson correlation coefficient between H-B formula and DRI formula was 0.996 (p<0.01) while that between Inbody value and DRI formula was 0.872(p<0.01). The Pearson correlation coefficient between Inbody value and H-B formula was 0.851(p<0.01).

4. Total energy expenditure calculated by H-B formula, DRI formula, and ER was 2184.4kcal, 2164.5kcal and 2102.1 kcal, respectively. Their values are very similar to each other. However the Pearson correlation coefficient between H-B TEE and DRI EER formula was 0.512 (p<0.01) while that between ER and DRI EER formula was 0.604(p<0.01). The Pearson correlation coefficient between ER and H-B formula was 0.795(p<0.01).

5. Comparison of BMR according to PAL showed that BMR of active group was significantly(p<0.05) higher than that of sedentary group except Inbody data. However Both BMR and TEE of overweight & obese group was significantly higher than those of underweight group in all three different formula.

Overall data indicate that female university students who participated in this study appeared to be less physically active because 11.6% and 53.7% of subjects belong to sedentery and less active group, respectively according to PAL. They still lack physical activity. Therefore it is recommended that universities develop good exercise program for their students.