The aim of this observational study is to identify biomarkers in extracellular vesicles associated with medullary adiposity occurring in patients with anorexia nervosa. The main question it aims to answer is:

Can this medullary adiposity be associated with the bone deterioration observed in this population?

Participants will be assessed for body composition and a blood sample will be taken by non-invasive techniques.

Inclusion Criteria:

For AN group:

• Diagnosis of active AN according to DSM-5 criteria
• BMI of less than 17kg/m2
• Present amenorrhoea in the 3 months prior to the start of the study.

For AN-R group:

• Achieved weight gain of more than 85%.
• Normal menstruation in the last 3 months.

For Control group:

• Population of the same age and gender as the AN and AN-R groups.
• If pubertal population, presenting a chronological age of ± 2 years.
• Normal menstruation
• Normal BMI (>18.5 kg/m2)
• No presence of previous dietary transtrons.

Exclusion Criteria:

• Not receiving oestrogens, contraceptives or glucocorticoids in the 3 months prior to the start of the study.
• Not to suffer from chronic diseases, such as diabetes, pathologies affecting the bone system or thyroid function.
• Do not take calcium or vitamin supplements.

The study population will consist of patients diagnosed with active anorexia nervosa according to DSM-V criteria (AN group), with a clinical history in the Clinical Management Unit of Endocrinology and Nutrition of the HURS, patients recovered from the disease (AN-R group) and healthy population of the same age and gender as the patients in the previous groups (CON group).