**4. Exercise as a beneficial part of treatment for BN**

Although physical activity can be performed with compulsivity and in excessive amounts, properly dosed physical activity can also be beneficial as a part of the treatment for BN. Sundgot-Borgen et al. (2002) randomly assigned young adult females with BN to exercise, cognitive behavioral therapy, nutritional counselling or waiting list control. The exercise program was superior to cognitive behavior therapy and nutritional counselling in improving drive for thinness, body composition and aerobic fitness, and in reducing binge/purge episodes. Unfortunately, this is to my knowledge the only publication that has examined the effect of exercise in treatment of BN using a randomized controlled trial design. It is therefore necessary to carry out more studies to replicate this finding.

Studies on other eating disorders such as binge eating disorder and anorexia nervosa have found physical activity to be beneficial in reducing co morbidity of depression and anxiety, and in enhancing quality of life (Hausenblas, Cook, & Chittester, 2008). In addition, physical activity can help the patients improve social bonding and relations. For patients who undergo heavy psychotherapy etc., the physical activity can be a nice distraction and time off from these exhausting and mentally painful processes. A clinical and practical experience is that the activity needs to be pleasurable and non-competitive. There is a need for studies that examine if a certain type of exercise (e.g. endurance training, strength training, pilates or yoga) is superior to others. Important outcome variables are change in eating disorder psychopathology, general psychopathology, body dissatisfaction and image, self esteem, quality of life, physical fitness, body composition, bone health, exercise dependence and motives for physical activity. As mentioned, we found about 10 percent of the patients to be insufficiently physically active (Bratland-Sanda, 2010), and a significant number of patients with BN are overweight or obese. Therefore, these patients need to increase physical activity level. This issue of inactivity among patients needs to be thoroughly emphasized during the treatment period. However, it must be done in a way that will enhance health and enjoyment without increasing the focus upon body weight and shape. It is therefore my recommendation that personnel with education in exercise physiology and exercise psychology must be in charge for the physical activity as part of BN treatment.

#### **4.1 Contraindications to physical activity and exercise among patients with BN**

There are several medical complications related to BN, among others oral, gastrointestinal and electrolyte complications (Mehler, 2011). Especially the electrolyte abnormalities are important to take into consideration when considering physical activity among the patients. The levels of e.g. sodium and chloride can decrease or increase dependent of type of purging method (Mehler, 2011). With both vomiting, use of laxatives and use of diuretics, the levels of potassium in serum and urine will decrease. Low potassium levels, also referred to as hypokalemia, have been found in approximately 5% of the BN population, and this condition can lead to e.g. cardiac arrhythmias. During physical activity, such lethal cardiac arrhythmias can occur (Bouchard, et al., 2007).
