Tehran University of Medical Sciences Journal of Biostatistics and Epidemiology 2383-4196 6 2 2020 12 13 107 114 Negin Badrooj Department of nutrition science, Faculty of science and medical technology, Islamic Azad University, Sciences and Research Branch, Tehran, Iran Seyed Ali Keshavarz Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), PO Box 14155-6117, Tehran, Iran Mir Saeed Yekaninejad Department of Epidemiology and Biostatics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Khadijeh Mirzaei Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), PO Box 14155-6117, Tehran, Iran 2020 09 26 2020 09 29 Aim: The aim of this study was to investigate the association between circadian rhythm with resting metabolic rate (RMR) in overweight\obese women Methods: This cross-sectional study included 232 obese and overweight women. Morningness-Eveningness Questionnaire (MEQ) was used to assess the level of circadian rhythm. RMR was measured by indirect calorimetry after a 10-12 hour overnight fasting period by a trained nutritionist. We assessed body composition using multi-frequency bioelectrical impedance analyzer (BIA). Results: The percentage of overweight and obese women were 48.7% (113) and 51.3% (119), respectively. The number of participants who were morningness, intermediate and eveningness was 28(12.1%), 135(58.2%) and 69(29.7%) respectively. A significant relationship was found between MEQ and RMR.normal (p=0.011). According to linear regression model non-eveningness participants had 81.92 higher RMR compared to eveningness participants (p=0.027). Conclusion: We found that non-eveningness participants had higher RMR compared to eveningness participants that can lead to obesity, diabetes type2 and other health disorders. https://jbe.tums.ac.ir/index.php/jbe/article/view/397