Anorexia nervosa is an eating disorder in which people have a distorted body image. Sufferers see themselves as overweight, regardless of their actual weight, and become obsessed with food, eating, and losing weight. People who suffer from anorexia often consume so few calories that they become emaciated and malnourished. Anorexia nervosa itself is treated as a mental illness, and it is often associated with other mental illnesses such as depression and suicide.
The consequences of anorexia can be deadly. According to [U.S. News and World Report](http://health.usnews.com/health-conditions/mental-health/eating-disorders/overview# 1), 90 percent of people with anorexia are young women. The disease accounts for 86 out of 100,000 deaths among young women aged 15 to 24.
One reason people with anorexia don't eat is thought to be due to an imbalance in brain chemistry. In a study published in the American Journal of Psychiatry, researchers found the part of the brain that associates the taste of food with pleasure is extremely underactive in women with anorexia. Another study out of Italy reports that the endocannabinoid system does not function properly in patients with anorexia. The endocannabinoid system is tied to homeostasis -- a balance in the body's functions -- within the brain. In patients with anorexia, however, cannabinoid receptors are dysfunctional in the portion of the brain that plays in role in food intake.
Cannabis has been linked to stimulating appetites for thousands of years, but only in the 20th century was the connection made to look at the chemical composition of cannabis and how it may help people with anorexia. Studies show that delta-9 tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, can successfully stimulate appetite in both cancer and AIDS patients. Tim C. Kirkham, a PhD and professor of Psychological Science at the University of Liverpool in England, has published extensively on the neurochemistry of appetite. He has found that THC binds to cannabinoid receptors in the brain that are responsible for appetite. The THC not only improves appetite, but promotes the rewards of eating, allowing patients to experience the joy of eating again.