The contribution of anxiety and food restriction on physical activity levels in acute anorexia nervosa.

OBJECTIVE Excessive exercise is present in 40%-80% of anorexia nervosa (AN) patients. Hyperactivity often plays a role in developing and maintaining AN and represents an obstacle to weight gain in refeeding. Interconnections among caloric restriction, psychopathology, and physical activity in humans with AN are poorly investigated. METHODS Physical activity and food restriction during the last 3 months and status of body image/slimness ideal were assessed by the Structured Interview of Anorexia and Bulimia Nervosa (SIAB) in 30 adolescent patients with acute AN at admission to inpatient treatment. Anxiety, depression, and obsessive-compulsiveness were assessed with the Symptom Check-List-90-Revised (SCL-90-R). A regression model based on the independent variables body mass index, food reduction, body image/slimness ideal, anxiety, depression, and obsessive-compulsiveness was calculated to determine the relevant prediction variables of physical activity. RESULTS The regression model explained 64% (R(2) = .64, p = .000) of the variance of physical activity. Only food restriction (p = .006) and anxiety (p = .004) contributed significantly to the variance. DISCUSSION Our results indicate that anxiety symptoms and food restriction synergistically contribute to increased levels of physical activity in the acute phase of AN.