Activity Anorexia is known as an abnormally high level of activity accompanied by a low level of food intake that is generated by an exposure to a time restricted schedule of feeding. In order to create the conditions to produce activity anorexia in rats you must follow a very detailed and specific set of rules. Test subjects (rats) are exposed to food once a day for an hour and a half, during the other hours of the day the rat will have access to a running wheel. If done properly, the test subjects will then start to spend more and more amounts of time running during the time period where they do not have access to food. It is also found with activity anorexia in rats that the more they run on their wheel, the less food they will eat. If given about a week, the test subjects will be running very long distances, close to about 20,000 revolutions of the running wheel daily, which equates to about twelve miles a day, along with eating next to nothing. If the process is continued on, the text subjects will become emaciated and die. Typically, most experiments are ended prior to any test subjects death.
This link can provide greater insight into the usage and benefits of activity anorexia.