Background and Aims: To examine the effects of starvation and nutritional refeeding on heart rate variability (HRV) and heart rate in adolescents with Anorexia Nervosa. Method: For this publication we illustrate 3 precedential cases to explain our model of heart rate regulation in patients with Anorexia Nervosa. Results: The linear relationship between the range of normal RR-intervals, global heart rate variability (SDNN) and mean heart rate is explainable by the slope of the diastolic depolarization of sinus node cells, regulated by the funny channels. We demonstrate the relationship between caloric intake, heart rate and heart rate variability which is better explained by the regulation of the funny channels than by the autonomic nervous system. However, the impaired heart rate regulation induces dysautonomia, demonstrated in two patients who develop postural orthostatic tachycardia syndrome (POTS). Based upon this model we explain the therapeutics effects of beta blockers, midodrine and ivabradine in these patients. Discussion: Our model of heart rate regulation in patients with Anorexia Nervosa explains dysautonomia in these patients and the effect of refeeding on heart rate regulation. Treatment of the impaired heart rate regulation in these patients with beta blockers, midodrine and ivrabradine can improve the oftenunsatisfactory therapy results.