If the menstrual period lasts for more than three months, it is called secondary ammenorrhoea. Secondary means that the menstrual period has already started, but then stops. Secondary amenorrhoea is a typical symptom of anorexia. The cause is the extreme underweight, which leads to hormonal disorders.
If the fat content of the body is too low, it can not produce enough female sex hormones (estrogens), so that it comes to ovulation. The body works on the back burner. A pregnancy at this time would not make sense and would endanger mother and child. When gaining weight, it may take some time for the menstrual period to return to normal.
author:Dr. med. Julia Hofmann