Objectives：To learn the factors related to energy consumption among residents aged from 40～60 years in Nanjing. Methods：A total of 110 men and women were recruited in Nanjing，their height and body weight were measured，and then body mass index (BMI) and body surface area (BSA) were calculated. The body composition information was recorded according to the dual energy X-ray body scanner. The energy consumption was respectively observed for flat-lying，exercising，internet browsing，sleeping，and rest metabolism during 11 hours they lived in the metabolism chamber. The relationship was analyzed between the energy consumption of different activity states and age，gender，body weight，height，BMI or body composition. Results：①The basal metabolism of male and female subjects was (2 036.25 ± 226.45) kcal/d，(1 673.21 ± 173.37) kcal/d，respectively，the difference was significant (P<0.01)；There were no significant differences in basal metabolism between subjects of different age groups (P>0.05). The energy consumption of women at different activity states was significantly higher than that of male (P<0.01) when energy expenditure (EE)/fat-free mass (FFM)；However，there were no significant differences in energy consumption between subjects at different ages when EE/FFM (P>0.05). ②The energy consumption of male and female subjects was significantly correlated with FFM，body weight，BSA，BMI，and body fat (P<0.01). According to the multiple regression analysis，it was found that the energy consumption under different active states was affected by gender，body fat，and FFM (P<0.05). Conclusion：The energy consumption of different activity states is mainly related to the FFM and body fat among the residents aged from 40～60 years in Nanjing.