This study aimed to examine the psychophysiological changes resulting from two mirror exposure treatments that are effective at reducing body dissatisfaction. Thirty‐five university women with body dissatisfaction and subclinical eating disorders were randomly assigned to one of two groups: pure (n = 17) or guided exposure (n = 18). The participants received six sessions of treatment. Their thoughts, feelings and avoidance behaviours were assessed after each session. Their subjective discomfort, heart rate and skin conductance were assessed within the sessions. Both groups showed improvement in cognitive‐affective and avoidance behaviour symptoms. Nevertheless, the pure exposure group showed faster habituation of subjective discomfort and a greater physiological response than the guided exposure group. These findings suggest that both procedures are effective interventions for improving body image disturbances, although psychophysiological changes observed within session suggest that each technique would act through different processes. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.