Patients who suffer form anorexia nervosa suffer from a psychological condition that causes them to develop an eating disorder in which they develop a fear of eating and an unhealthily low body weight. Whaxy says, "In addition to severe weight loss and malnutrition, anorexia can result in anemia, digestive problems, loss of bone density, and heart-rhythm disturbances - as well as imbalances in hormone and electrolyte levels." Because anorexics are not nourishing properly, patients who suffer from the condition can lack energy, feel fatigue, become week, and develop a weak immune system making it difficult to combat common minor illnesses. It is estimated five percent of long term sufferers will die from the condition in a ten year span.
Some consider appetite stimulation to be one of the top three efficacies of cannabis, making it a potential candidate for combatting anorexia. Cannabis' ability to stimulate appetite is likely because of the body's endocannabinoid system playing a significant role in mediating hunger and stimulating appetite. A study published in the journal Biological Psychiatry in 2011 "found a link between anorexia nervosa and bulimia based on a brain malfunction that leads to a loss of endocannabinoids. Because the endocannbinoid system is known to regulate bodily functions such as hunger, this endocannabinoid deficiency results in a distortion of appetite."
Studies exist demonstrating the ability of cannabis to stimulate appetite in patients with Alzheimer's, cancer, or HIV/AIDS who suffer from a loss of appetite, so researchers believe these results could be applied to those who suffer from anorexia as well. However, one important thing to note is that the underlying cause of anorexia nervosa is psychiatric, as opposed to a physical loss in appetite. Therefore, cannabinoids often have little similar success. Whaxy explains, "This study illustrates that anorexia is a psychiatric condition that manifests itself physically, for which the appetite stimulation provided by cannabis may not be a complete solution or target the root cause."
That being said, one study in 2014 conducted on rodents remained hopeful. The study, which was published in the journal Innovations in Clinical Neuroscience, placed rodents into an anorexic state of being and found only rodents that were administered cannabinoids during the test recovered completely after regular diets and exercise levels returned to normal. Those that did not receive cannabinoids remained in an anorexic state despite the food conditions returning to normal.
Be sure to check out Whaxy's full article, which discusses the subject in great detail.