Sports and exercise are healthy activities for young girls and women of all ages. But a female athlete who focuses on being thin or lightweight may eat too little and/or exercise too much. Doing this can cause longterm damage to health, or even worse. It can also hurt athletic performance and/or make it necessary to limit or stop exercise. Three interrelated illnesses may develop when a young woman goes to extremes in dieting or exercise. Together, these conditions are known as the "female athletic triad."