Excess post-exercise oxygen consumption (EPOC) increases caloric burn during the recovery period, to be considered in relation to energy balance and weight loss. The aim of this study was to evaluate the acute effects of various modes of aerobic exercise of moderate intensity on EPOC in a lean (NW) and obese (OB) female population. Methods A population of moderately active lean and obese female (NW: age, 24,3±0,6 yr; BMI, 23,1±2,1 kg/m2; OB: age, 36,3±4,5 yr; BMI, 31±5,4 kg/m2) participated in the study over a 3-week period. Subjects filled a Baecke questionnaire of habitual physical activity and undergone 3 incremental tests to exhaustion (V’O2peak at treadmill, cycle ergometer and arm ergometer). Thereafter they completed five bouts of 30 min of exercise separated by at least 48 hours of rest: treadmill walking_TE, cycling_ CE, arm crank exercise_AE, cross-training exercise combining walking, cycling and arm crank for 10 min each_CTE (60% of V’O2peak) and daily living activities_DLA (3-6 METs). Before (30 min pre) and after (2 hours post) each exercise bout a resting metabolic rate measurement was carried out in a sitting position (K4b2, Cosmed, Italy). A repeated measures ANOVA was used to analyse data. Results EPOC magnitude was not significantly different for the two groups, except for CTE (NW, 9±4,2 l; OB, 2,4±2,4 l; p<0,05), and accounted between 5% and 15% of total energy expenditure (TEE150min). V’O2 during exercise (V’O2ex) and TEE150min were similar for both groups (NW: V’O2ex, 1,3±0,3 l/min; TEE150min, 320,4±57,1 kcal; OB: V’O2ex, 1,2±0,3 l/min; TEE150min, 306,6±45,9 kcal; p=ns). Respiratory exchange ratio was significantly lower for NW when compared with OB during exercise, allowing a greater fat utilization (NW: QR, 0,8±0,1; FAT, 95,1±43,3 kcal; OB: QR, 0,9±0,1; FAT, 59,1±32,5 kcal; p<0,05 and p<0,001, respectively). Discussion This study indicates that analysed aerobic exercises, included DLA, elicit similar EPOC responses. These findings confirm (i) the magnitude of EPOC (LaForgia, 2006), (ii) that women who are lean or obese respond similarly to aerobic exercise at similar relative intensities (Crommett, 2004; LeCheminant, 2008) and (iii) that exercise-induced fat oxidation is diminished in obese women, as it was already demonstrated for men (Wong, 2006). References Crommett. J Strength Cond Res. 2004 Aug;18(3):410-5. LaForgia. J Sports Sci. 2006 Dec;24(12):1247-64. Wong. J Clin Endocrinol Metab. 2006 Feb;91(2):678-86. LeCheminant. Int J Sports Med. 2008 Jan;29(1):53-8.