The role of exercise as adjunctive therapy for people with ED is controversial, despite the fact that physical activity can play an important role in both ED and AOD use, in terms of treatment, recovery, and relapse prevention [947]. The benefits associated with exercise in ED include the promotion of physical activity and weight loss to people with binge eating disorder [948], and the potential prevention and restoration of bone mass in people with anorexia nervosa [949]. However, based on the belief that exercise may interfere with weight gain or reinforce the psychological/pathological symptoms of ED, it is not uncommon for ED treatment providers to limit the amount of physical activity, allowing little or no exercise [947]. There is also the potential that physical activity may lead to compulsive ‘overexercising’ [950].
Although physical activity has not been evaluated among people with comorbid ED and AOD use, several studies have examined exercise in people with single disorder ED and have found moderate physical activity to be associated with weight gain in underweight people with anorexia nervosa [951, 952]. One small pilot study has been conducted examining a graded exercise program based on ideal body weight and percentage body fat, with exercises ranging from stretching, to strengthening and low-impact cardiovascular exercise three times per week for three months [951]. The exercise group demonstrated improvements in weight gain as well as quality of life, which were substantially greater than the inactive control group, whose quality of life decreased over the study period.
Another study examined the effectiveness of an exercise program on weight gain among women with anorexia nervosa, bulimia nervosa and binge eating disorder in an inpatient treatment facility, and found that 60 minutes of supervised exercise conducted four times per week was associated with 40% more weight gain than the inactive control group [952]. The exercises included stretching, yoga, Pilates, strength training, balance, exercise balls, aerobic exercise (e.g., walking or skipping), recreational games, or other enjoyable activities [952]. It is suggested that moderate physical activity facilitates weight gain by improving emotional well-being, increasing appetite, and reducing body-image and appearance-related distress [947].
Although preliminary evidence supports the positive impact of exercise for people with ED, it remains unclear as to how clinicians should approach physical activity among underweight people, or people who may be normal weight but have been treated for compulsive exercise in the past [947]. Despite promising research, the evidence suggests that caution should be taken when recommending exercise for people with ED, particularly anorexia nervosa, as the presence of behaviours which are indicative of problematic exercise may negatively impact on the long-term course of illness [947, 953], and thus, hinder potential positive outcomes.