Female Runner No Longer Menstruating?

Hormones are stored in body fat - too much or too little and your period is likely to stop. Sounds as if your body fat level is too low. You are starving your body, and it is reacting by making sure you don't carry a baby in your starved condition. But your period may show up at any time, so don't use this as a birth control method as it is very unreliable. Try to gain a couple of pounds - and tell your Mom so she can help you.