Purpose: The aim of this study was to compare objective and subjective assessments of physical activity (PA) in patients with anorexia nervosa and its effect on treatment outcome.
Methods: Both Actiheart (AH) and International Physical Activity Questionnaire (IPAQ) were used to assess PA in 52 female patients with anorexia nervosa during the first week of inpatient treatment.
Results: No correspondence between PA estimated by IPAQ, which had a tendency to underestimate PA, and that measured using AH emerged. However, a significant association was found between the change in Eating Disorder Examination global score at the end of the treatment and light PA measured by AH (beta = −0.12, t = −2.44, P = 0.019), but not that estimated by IPAQ.
Conclusions: PA in patients with anorexia nervosa is underestimated by subjective assessment when compared with objective measurement. Only time spent in light PA, assessed objectively with AH, showed a negative association with improvement in eating disorder psychopathology.