Secondary amenorrhoea (menstrual cycles ceasing) is often caused by hormonal disturbances from the hypothalamus and the pituitary gland, from premature menopause or intrauterine scar formation. It is defined as the absence of menses for three months in a woman with previously normal menstruation, or six months for women with a history of oligomenorrhoea. Another potential cause for amenorrhea is in the presence of a severe eating disorder, like Anorexia Nervosa, characterized by food restriction and being underweight. 66%-85% of patients with Anorexia Nervosa present amenorrhea as a symptom.