What causes the Female Athlete Triad?

Energy Deficit / Disordered Eating

An energy deficit occurs when the amount of energy consumed in the diet is less than the amount of energy expended by the body.  An energy deficit is necessary to reduce body weight and fat which are common goals in athletic training.  The Female Athlete Triad is caused by an excessive energy deficit that occurs when the amount of dietary energy remaining after exercise training is less than the amount the body needs for other functions.  In some athletes with excessive energy deficits, diet and exercise habits are motivated by problems with body image and a high drive for thinness that may involve disordered eating or serious illnesses such as anorexia or bulimia.
 
Menstrual Dysfunction / Amenorrhea

The most serious menstrual problem associated with the Triad is amenorrhea, defined as no menstrual period for three months or more. However athletes who have irregular menstrual cycles are also susceptible to the performance and health consequences of the Triad.
 
Bone Loss / Osteoporosis

Women with the Triad are at higher risk of low bone mass leading to weakened bones, called osteoporosis in its severe form. This type of bone loss can cause an increased risk of fractures, including stress fractures.