Background: The aim of this study was to determine the acute effects of exercise intensity on anxiety, mood states and hunger in obese adolescents.Methods: Subjects were eight male obese adolescents (age 15.44 ± 2.06y; BMI 33.06 ± 4.78 kg/m 2). Each subject underwent three experimental trials: 1) Control, seated for 30 min; 2) Low intensity exercise (LIE) - exercise at 10% below ventilatory threshold (VT); 3) High intensity exercise (HIE) - exercise at 10% above VT. Anxiety (STAI Trait/State), mood (POMS) and hunger (VAS) were assessed before and immediately after the experimental sessions. Comparisons between trials and times were assessed using Kruskal-Wallis and Wilcoxon tests, respectively. Associations between variables were described using a Spearman test.Results: The largest increase in hunger was observed after LEI (914.22%). Both exercise sessions increased anxiety, fatigue and decreased vigor (p < 0.05).Conclusions: Acute exercise bouts are associated with negative changes in anxiety and mood, and with increases in hunger in obese adolescents. © 2012 Lofrano-Prado et al; licensee BioMed Central Ltd.