REVIEW High Levels of Physical Activity in Anorexia Nervosa: A Systematic Review Ricarda Gümmer * , Katrin Elisabeth Giel, Kathrin Schag, Gaby Resmark, Florian Philipp Junne, Sandra Becker, Stephan Zipfel & Martin Teufel Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany Abstract High level physical activity is a frequent symptom in patients with anorexia nervosa (AN), influencing the development, maintenance, complications, treatment success, relapse rate and severity of the disease. Accelerometry is assumed to be an objective method to assess physical activity (PA) in AN. We aimed to review objectively measured levels of PA in AN and to give an overview for clinical practice and future research. Data were searched in PubMed and PsychINFO until April 2015 following the preferred reporting items for systematic reviews and meta-analyses statement. Twenty studies fulfilled the inclusion criteria. A notable heterogeneity of measurements, outcomes, participants and settings was found. Overall, HLPA is not adressed enough by current evidence. A common valid terminology of HLPA is not available, and accurate criteria of different levels of PA must be defined to create comparability of future studies. Further objective PA assess- ments are needed to improve treatment outcome and relapse rate. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association. Keywords Anorexia nervosa; Physical activity; Accelerometry *Correspondence Ricarda Gümmer, Internal Medicine VI, Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Osianderstraße 5, Tübingen, 72076, Germany. Email: ricarda.guemmer@med.uni-tuebingen.de Published online 18 June 2015 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/erv.2377 In anorexia nervosa (AN), insufficient food intake causes the patient to be severely underweight. Additionally, high levels of physical activity (PA) occur in 31%–80% of patients with AN (Hebebrand et al., 2003) and lead to severe complications. Despite this fact, an elevated PA level is only a second order symptom for AN according to diagnostic and statistical manual 5. In treatment programmes, PA is often not directly addressed, and there are no standardized guidelines for special treatment of execessive exer- cisers with AN (Zunker, Mitchell, & Wonderlich, 2011). Increased PA has been described in AN since 1868 (Gull, 1997), but there is a lack of a common definition for elevated PA in AN (Bratland-Sanda, Sundgot-Borgen, et al., 2010b). A great variety of descriptions can be found in the literature addressing the same phenomenon. Besides the various descriptions of manifestations, contradictory explanations of the causes and consequences of PA can be found. The heterogeneity of hypotheses and evidence makes it difficult to measure and interpret PA in AN and difficult to compare the results. Physical activity in AN has been described as hyperactivity, overactivity, paradoxical overactivity, motor restlessness, diffuse restlessness, compulsive exercise or excessive exercise. This might be partly due to the various manifestations of PA in AN (Hebebrand et al., 2003): long-distance running or cycling, exces- sive participation in fitness programmes at the gym and any other type of high intensity PA or long-lasting sport are often practised by affected patients. Besides sports, PA can be easily integrated into everyday activities such as uninterrupted fidgeting, standing instead of sitting while studying or watching television, carrying heavy bags, taking the stairs instead of the elevator, walking in- stead of taking the bus or doing sit-ups in public restrooms. Whether the different terms describe the same phenomenon and whether psychological components such as inner restlessness are included remain uclear. We will use the term high level phys- ical activity (HLPA) for all kinds of elevated PA mentioned in this paper, as it can be utilized for all forms of PA, including sports and everyday activities, as an understandable topic term. This term has been used similarly before (Kostrzewa et al., 2013). HLPA includes PA but no psychological aspects such as inner restlessness. The origin of HLPA in AN has been controversially discussed. HLPA can be seen as a conscious action with the aim to burn calories and control shape or weight, meaning the ‘relentless pursuit of thinness’ (Dalle Grave, Calugi, & Marchesini, 2008). But there is also evidence that HLPA can be an unconscious, uncontrolled symptom: neurobiological ex- planations for HLPA in AN have been reviewed by Matta Mello Portugal et al. (2013). Alterations in thyroid and serotonergic and catecholaminergic systems have been found in AN (Hebebrand et al., 2003). This regulation by hormones would support the hypothesis that HLPA is a phylogenetically old mechanism for survival in a famine state (Scheurink, Boersma, Nergardh, & Sodersten, 2010). Leptin, for example, is a fre- quently discussed hormone that triggers the adaption of an or- ganism to food restriction. Changes in body fat are reflected by 333 Eur. Eat. Disorders Rev. 23 (2015) 333–344 © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.