Bulimia nervosa is an eating disorder usually characterized by periods of binging – or excessive overeating – followed by purging. People with bulimia have a fear of gaining weight; however, that does not mean all people with bulimia are underweight. Some people with bulimia are overweight or obese. They attempt to use purging to manage their weight or prevent additional weight gain. Bulimia nervosa is a serious mental illness that requires intensive treatment. Getting help for your bulimia gives you the best chance to overcome this eating disorder.