People with AN have an intense fear of gaining weight or becoming fat even though the person is underweight. Their body weight is less than 85% of the normal body weight. In women who have already begun their menstrual cycle, at least three consecutive periods are missed(amenorrhea), or menstrual periods occur only after a hormone is administered.

People with anorexia starve themselves, avoid high-calorie foods and exercise constantly. People with bulimia eat huge amounts of food, but they throw up soon after eating, or take laxatives or diuretics (water pills) to keep from gaining weight. People suffering from bulimia don't usually lose as much weight as people with anorexia.

Approximately 0.5% to 3.7% of women will suffer from AN at some point in their life. It usually begins between the ages of 13 to 30 years. Approximately 95% of those affected by anorexia are female, but males can develop the disorder as well. In the U.S. and other countries with high economic status, it is estimated that about one out of every 100 adolescent girls has the disorder. Anorexia is more common in middle and upper socioeconomic groups.

Family and twin studies have suggested that genetic factors contribute to about 50% of the variance for the development of an eating disorder. Scientific literature has suggested that anorexia is linked to a disturbed serotonin system. People with anorexia have been found to have certain personality traits that are thought to predispose them to develop eating disorders. High levels of obsessionality (being subject to intrusive thoughts about food and weight-related issues), restraint (being able to fight temptation), and clinical levels of perfectionism are commonly reported factors in research studies. The role of cultural factors, such as the promotion of thinness as the ideal female form in Western industrialized nations is also one of the important reasons people develop this disorder.

• Restricting Type:The person will restrict their diet. They will not purge.
• Binge-Eating Type or Purging Type:The person has regularly engaged in binge-eating OR purging behavior

People with Anorexia nervosa will have combination of physical and emotional problems. As they will not eat well or throw up a lot they will develop many medical problems like constipation, diarrhea. They will be fatigued easily. Their menstruation will be stopped. Their puberty will be delayed. They can get dry skin, brittle nail, dizziness. They can develop low blood pressure and irregular heart rhythm. They can also develop kidney stones. They will also have many emotional problems like depression, anxiety and substance abuse. They are also at risk of committing suicide or dying because of medical complications.

Anorexia can be chronic and difficult to overcome. But with treatment a person can return to healthier eating habits and reverse some of anorexia's serious complications. Without treatment a person can get many medical problems and have frequent hospitalization.

Different kinds of psychological therapy have been employed to treat people with anorexia. Individual therapy, cognitive behavior therapy, group therapy, and family therapy have all been successful in treatment of anorexia. While no medications have been identified that can definitively reduce the eating disorder pattern, some of the antidepressants help with the depression and anxiety symptoms that a person suffers when they are having Anorexia Nervosa.