To date there is no conclusive evidence linking bulimia to such biological factors as chemical imbalance in the brain. According to one theory, after you have eaten a usual amount of food, your brain sends a message to turn off the desire to eat more. But if you have starved yourself or followed a strict diet between binges, you are in a food-deprived state. When you resume eating during a binge, the turnoff message may fail to work. You then continue eating well beyond the point where you ordinarily would stop.

A few researchers have suggested that physical, psychological, or especially sexual abuse in childhood may cause bulimia later in life. These findings are controversial, and the role child abuse plays in causing bulimia is unclear.

Social pressures could also play a part. Society's emphasis on thinness as the ideal form of feminine beauty may be what causes some young women to become so afraid of the idea of becoming fat that they fall into the binge/purge pattern of bulimia. One thing is certain: If you are susceptible to bulimia, your first episode may be triggered by a stressful situation such as school problems, a death in the family, career changes, divorce, or pregnancy.