Women with eating disorders, such as anorexia nervosa, often do not have their periods. Athletic amenorrhea is caused by endurance training. As many as 20 percent of racing runners do not have periods. Female athletes often skip or have no periods. This is harmless and can be reversed.
Monthly periods return with weight gain and less training.
Get a medical check-up to be sure no other problems are causing the missed periods. Heavy training schedules can lower body fat. The ovaries stop making estrogen when body fat is too low. Estrogen is the hormone needed for ovulation and menstruation. A low level of estrogen may result in bone loss, heart disease, and cancer.