Eating 2.2% (Keski-Rahkonen et al., 2007). Anorexia Nervosa has

Eating disorders like Binge eating, Bulimia Nervosa or Anorexia Nervosa are prevalent disorders with serious outcomes. Especially Anorexia Nervosa (AN) is a very prevalent disorder. According to the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2013) Anorexia Nervosa is characterized by a restricted food intake leading to a significantly lowered body weight determined through a body mass index between 15-17. Another characteristic is the extreme fear of gaining weight and counteracting strategies like dieting or exercising. The last characteristic of Anorexia Nervosa according to the DSM-5 is a distorted body-image.According to the DSM-5 there are two subtypes of Anorexia Nervosa the restrictive type and the purging type. The restrictive type is characterised by restricted calorie intake and/or excessive exercising. The purging type is characterised by purging as counteracting strategie. At risk are especially girls between 15-19 years, with an incidence of 270 per 100.000 person-year and a lifetime prevalence of 2.2% (Keski-Rahkonen et al., 2007). Anorexia Nervosa has several severe consequences up to death, the most common consequence is malnourishment which leads to several severe medical problems like low body temperature, low blood pressure, low bone density, low heart rate, amenorrhoea, swelling, metabolic and electrolyte imbalance, dry skin, brittle nails, poor circulation and lanugo (Misra et al.,2004). Concluding Anorexia Nervosa has to subtypes with severe Consequences ranging from medical problems like for example low heart rate up to death.Up to now the most prominent treatment for Anorexia Nervosa is cognitive behavioral therapy. Causes for the use of cognitive behavioral therapy as intervention for Anorexia Nervosa or other eating disorders is the nature of the disorder itself. From a Cognitive behavioral view three mechanisms contribute to the maintenance of Anorexia Nervosa firstly the food intake restriction strengthens the feeling of being in control. The second mechanism involved is that facets of starvation lead to an increased restriction of food. Namely that the intense hunger and the impaired concentration caused by the state of starvation lead to a perceived threat to the control of the eating behavior. The third mechanism that is involved is a culture specific mechanism and especially common in the western cultures where thinness is a beauty ideal the third mechanism is namely is the extreme concerning about weight and shape which lead persons to behaviour that counteracts gaining weight (Fairburn, Shafran and Cooper, 1998). Summarizing Cognitive behavioral therapy tackles the maintaining of  Anorexia Nervosa with the use of cognitive strategies to tackle the mentioned cognitive biases and behavioral strategies to mainly approach the underweight and restore the regular weight again. Another intervention for eating disorders and especially Anorexia Nervosa is nutritional counseling. In nutritional counseling the diet of a patient is assessed and if it is necessary changed, usually with the help of a dietitian, the dietitian also provides the patient with support and informative material. In a research conducted by Pike, Walsh, Vitousek, Wilson and Bauer (2003) 33 adult patients who match the  DSM-5 criteria for Anorexia Nervosa after hospitalization were randomly assigned to either a 1 year nutritional counseling or a 1 year Cognitive behavioral therapy condition. The research shown that less anorexia nervosa patients who underwent cognitive behavioral therapy relapsed compared to patients who underwent nutritional counseling. Although the study showed that Cognitive behavioral therapy  seems to be more successful for the treatment of Anorexia Nervosa as nutritional counseling, there was for more than a half of the Cognitive behavioral group a not “good outcome”. Another commonly used treatment for Anorexia Nervosa is Family based Therapy (FBT) which is especially used for adolescents. The family based therapy is structured into three phases. In the first phase the positive aspects of the parenting from the parents is highlighted and thoughts concerning the responsibility of causing Anorexia Nervosa diminished, in order to encourage the family to work on themselves and build a foundation for the restoration of the patients normal weight.  From these studies emerges the problem constituting this research, namely that there is still not an efficient intervention for the treatment of Anorexia, with  Another possible promising therapy for Anorexia Nervosa is the Acceptance and Commitment Therapy. Acceptance and Commitment Therapy is an intervention which is counted to the so called third wave behaviorism. This study tries to answer the question whether Acceptance and Commitment Therapy compared to Cognitive behavioral therapy is an effective intervention for the treatment of  Anorexia nervosa. With the goal to hopefully pave the way for a new successful intervention for people who suffer from Anorexia Nervosa. From studies of Heffner, Sperry, Eifert and Detweiler (2002) and the series of case studies from Berman, Boutelle and Crow (2009) it is known that mindfulness-based strategies as part of treatment for Anorexia Nervosa resulted in reduced eating disorder related emotions and cognition as well as  an improvement in Anorexia Nervosa related behaviour. Based on the