Different nutritional states and autonomic imbalance in childhood.

Autonomic imbalance, measured as heart rate variability (HRV), and an increased cardiovascular risk are described for overweight children, as well as for patients with anorexia nervosa. We investigate whether body mass index or actual caloric intake influences HRV. In our cross-sectional study, we compared HRV parameters for a healthy control group (n=52), anorexia nervosa patients (n=17), thin (n=18) and overweight children (n=19). Anorexia nervosa patients showed significantly lower heart rates at night (P<0.001) and significantly higher SDNN (standard deviation of all RR-intervals) (P<0.001 ), whereas overweight children showed an opposing pattern. SDNN and heart rate at night are highly correlated (r=0.89, R(2)=0.79, P<0.001). We conclude that not current body mass index but caloric intake determines HRV. Obesity and anorexia nervosa are characterized by a specific pattern of autonomic imbalance.