The heart rate variability (HRV) is a measure of the autonomic nervous system (ANS). In the model of anorexia nervosa, ANS is disturbed with mostly a predominance of activation of the parasympathetic nervous system and a decrease of the sympathetic system. Various explanations of this these dysfunctions are proposed in literature, mainly malnutrition, physical hyperactivity, anxiety, that are known characteristics of anorexia nervosa.

The primary aim of this study is to evaluate correlation between ANS dysfunction and anxiety in anorexia nervosa.

Other objectives of this study are firstly to evaluate correlation between ANS dysfunction and others parameters (weight, body mass index, depression, physical activity, purgative ou restrictive type, duration of disease, smoking) in anorexia nervosa and secondly to see if HRV is a predictive parameter of the evolution of anorexia nervosa.

Inclusion Criteria:

• Women
• Aged from 18 to 65 years
• Criteria of anorexia nervosa (DSM V)
• Body mass index (BMI) < 18 kg/m2
• Written consent to participate in the study
• Patient affiliated to a social security system

Exclusion Criteria:

• Pacemaker or other implantable electronic device
• Current comorbidity psychiatric disorder according to Axis I of DSM IV : severe depression (BDI > 8/13), substance use disorder .
• Psychotropic drugs or ongoing steroid therapy ;
• Pregnancy or breast-feeding ;
• History or known cardiovascular disorder, including hypertension ( > 140/90 mmHg ) , heart failure, arrhythmia and conduction disorder .
• Major protected by a legal protection
• Minors
• Patient involved in another research with an exclusion period ongoing at the run-in