People with anorexia have a real fear of weight gain and a distorted view of their body size and shape. As a result, they eat very little and can become dangerously underweight. Many teens with anorexia restrict their food intake by dieting, fasting, or excessive exercise. They hardly eat at all — and the small amount of food they do eat becomes an obsession in terms of calorie counting or trying to eat as little as possible.
Others with anorexia may start binge eating and purging — eating a lot of food and then trying to get rid of the calories by making themselves throw up, using some type of medication or laxatives, or exercising excessively, or some combination of these.
With bulimia, people might binge eat (eat to excess) and then try to compensate in extreme ways, such as making themselves throw up or exercising all the time, to prevent weight gain. Over time, these steps can be dangerous — both physically and emotionally. They can also lead to compulsive behaviors (ones that are hard to stop).
To have bulimia, a person must be binging and purging regularly, at least once a week for a couple of months. Binge eating is different from going to a party and "pigging out" on pizza, then deciding to go to the gym the next day and eat more healthfully
People with bulimia eat a large amount of food (often junk food) at once, usually in secret. Sometimes they eat food that is not cooked or might be still frozen, or retrieve food from the trash. They typically feel powerless to stop the eating and can only stop once they're too full to eat any more, or they may have to go to extreme measures (like pouring salt all over a dessert to make it inedible) in order to get themselves to stop eating. Most people with bulimia then purge by vomiting, but also may use laxatives or excessive exercise.