Background: Patients with anorexia and bulimia nervosa are often ambivalent about their eating disorder symptoms. Therefore, a lack of motivation to change is a frequent problem in the treatment of eating disorders. This is of high relevance, as a low motivation to change is a predictor of an unfavourable treatment outcome and high treatment dropout rates. In order to quantify the degree of motivation to change, valid and reliable instruments are required in research and practice. The transtheoretical model of behaviour change (TTM) offers a framework for these measurements.
Objective: This paper reviews existing instruments assessing motivation to change in eating disorders.
Method: We screened N = 119 studies from the databases Medline and Psycinfo found by combinations of the search keywords 'eating disorder', 'anorexia nervosa', 'bulimia nervosa', 'motivation', 'readiness to change', 'assessment', 'measurement', and 'questionnaire'.
Results: Ultimately, n = 15 studies investigating psychometric properties of different assessment tools of motivation to change in eating disorders were identified. Reviewed instruments can be divided into those assessing the stages of change according to the TTM (6 instruments) and those capturing decisional balance (3 instruments). Overall, the psychometric properties of these instruments are satisfactory to good.
Discussion: Advantages, disadvantages, and limitations of the reviewed assessment tools are discussed. So far, the TTM provides the only framework to assess motivation to change in eating disorders.
Keywords: Anorexia nervosa; Assessment; Bulimia nervosa; Interview; Motivation to change; Questionnaire.