The impact of hyperactivity and leptin on recovery from anorexia nervosa

In anorexia nervosa (AN), hyperactivity is observed in about 80% of patients and has been associated with low leptin levels in the acute stage of AN and in anorexia animal models. To further understand the importance of this correlation in AN, we investigated the relationship between hypoleptinaemia and hyperactivity in AN patients longitudinally and assessed their predictive value for recovery. Body weight, activity levels, and serum leptin levels were assessed in adolescents and adult AN patient groups at the start and during treatment, up to a year. In the adolescent group, initial leptin and activity levels were correlated. This negative correlation changes over time into a positive correlation with physiological recovery. Treatment outcome in both groups could be predicted by initial BMI and leptin levels but not by activity levels. No major relationship of activity with the course of recovery was detected, suggesting that in contrast to the acute stage of the disease, leptin and activity levels during the recovery process are dissociated.