Objectives: This study aimed to investigate the energy expenditure of common office-based tasks. The objectives were to: (a) test the classification of tasks as sedentary or light-intensity physical activity and (b) compare the energy expenditure of tasks under two postural conditions (sitting and standing). Background: The sedentary nature of office work has been highlighted as a health risk, and strategies to reduce sedentary behavior at work have been devel- oped. However, there is limited evidence to guide the utilization of sit-stand workstations in the workplace for metabolic health benefits. Method: A repeated measures laboratory-based study compared the energy expenditure of common office tasks in sitting and standing using indirect calo- rimetry (n = 22). Four standardized tasks (sitting/stand- ing quietly, reading, typing, sorting paper) under two postural conditions (sitting, standing) were performed in a randomized order. Results: The mean energy expenditure for all tasks in sitting and standing was <1.5 METs. There were no sig- nificant differences in the energy expenditure of doing the same task in sitting compared to standing. In a repeated measures ANOVA, task (p < .001) had a greater influence on METs expended than posture (p = .030). Conclusion: The study confirmed that the differ- ence in energy expenditure of tasks carried out in sit- ting compared to standing is negligible. Application: The ubiquitous use and utility of sit- stand workstations in the workplace needs to be reviewed. Notwithstanding the potential benefits of movement that may occur naturally, this study confirmed that standing as opposed to sitting does not produce a clinically important increase in energy expenditure. Keywords: sitting, standing, energy expenditure, occupational, sit-stand workstation INTRODUCTION Sedentary behavior, which is pervasive in con- temporary society, was first highlighted as a risk factor to health in the 1950s with the landmark study on London bus workers (Morris, Heady, Raffle, Roberts, & Parks, 1953). Once thought to be the inverse of physical activity, sedentary behavior is now considered to be a distinct para- digm that affects health independent of physical activity (Chastin, Mandrichenko, Helbostadt, & Skelton, 2014; Hamilton, Hamilton, & Zderic, 2007; Owen, Leslie, Salmon, & Fotheringham, 2000) and is associated with adverse health out- comes, such as obesity, cardiovascular disease, type 2 diabetes mellitus, osteoporosis, some can- cers, and all-cause mortality (Biswas et al., 2015; Grontved & Hu, 2011; Proper, Singh, Van Mech- elen, & Chinapaw, 2011; Schmid & Leitzmann, 2014; Van Uffelen et al., 2010; Wilmot et al., 2012). Office workers have been identified as an occupational group that are sedentary for most of the working day (Mummery, Schofield, Steele, Eakin, & Brown, 2005; Thorp et al. 2012), and therefore the work/office environ- ment has been proposed as a suitable venue for public health initiatives to combat sedentary behavior (Conn, Hafdahl, Cooper, Brown, & Lusk, 2009; McCrady & Levine, 2009). Current public health advice to reduce total sedentary time (Garber et al., 2011) by replacing it with low-intensity non-exercise physical activity is intended to decrease the deleterious effects of work-related sedentary behavior. The beneficial effects of standing on cardio-metabolic risk bio- markers (Healy, Winkler, Owen, Anuradha, & Dunstan, 2015) and glucose concentration (Thorp, Kingwell, Sethi, et al., 2014) have been reported, and an association between self- reported occupational sitting time and obesity in men has been found (Mummery et al., 2005). Additionally, it has been shown that using a sit- stand workstation has beneficial effects on the 719167HFS XX X 10.1177/0018720817719167Human FactorsEnergy Expenditure in Standing Versus Sitting Address correspondence to Sara Dockrell, Discipline of Physiotherapy, School of Medicine, Trinity Centre for Health Sciences, St. James’s Hospital, James’s Street, Dublin 8, Ireland; e-mail: sara.dockrell@tcd.ie. Energy Expenditure of Standing Compared to Sitting While Conducting Office Tasks Jill Burns, Cuisle Forde, and Sara Dockrell, Trinity College, Dublin, Ireland HUMAN FACTORS Vol. XX, No. X, Month XXXX, pp. 1–10 DOI: 10.1177/0018720817719167 Copyright © 2017, Human Factors and Ergonomics Society.