The objective of this study is to compare energetic expenditure in day-to-day activities among subjects with internalizing disorders (depression and anxiety), externalizing disorders (attention deficit/hyperactivity disorder and oppositional defiant disorder) and healthy children and adolescents without any psychiatric diagnosis. One hundred and five (n = 105) students from a community sample were evaluated throughout a structured psychiatric interview and categorized into three groups: internalizing (n = 54), externalizing (n = 12) and typically developing controls (TDC, n = 39). Energetic expenditure was evaluated using 3-day physical activity record. Subjects with internalizing disorders performed activities with lower energetic expenditure as compared to those with externalizing disorders and TDC. Participants with externalizing disorders had more energetic expenditure variability. Our study suggests that internalizing disorders are associated with activities of low energetic expenditure in day-to-day activities, extending previous findings with physical exercise. These findings may further contribute to the understanding of the associated morbidity previously described in patients with internalizing disorders.