The amount of weight lost by each individual anorexic varies by person and how advanced her illness is. Orgclinic.com estimates that an anorexic individual can lose 15 to 20 pounds per month.
The speed of weight loss depends on the particular tactics used by the individual anorexic, according to Orgclinic.com. People with anorexia nervosa use various measures to drastically reduce food intake such as purging, taking laxatives and simply not eating.
Anorexics also tend to exercise excessively, says the Office on Woman's Health, a branch of the U.S. Department of Health and Human Services. The body responds to these actions by slowing the metabolism and breaking down the muscle tissues, among other system changes.
Anorexia is an eating disorder that can be fatal, according to the Office on Women's Health, but anorexics can get better with guidance from doctors, nutritionists and therapists.