Well, chances are if this person has stopped eating it will continue unless something changes. Without going into specific details Tristen, why did this person stop eating or do you even know? There are many reasons from just loss of appetite to body image problems and it could be something physical or psychological. I fast sometimes for a couple of days in order to give the digestive system a break and or to shrink the stomach in order to lose a few pounds, which I'm not suggesting to anyone, but a loss of appetite is not a good thing psychologically or physically.
If it is something psychological and if the person is a close friend, talk to the person about why they can't eat. Sometimes all we need is to let loose and then the appetite may come back.
As for eating like a normal person, I can't eat like a normal person or I gain way too much weight. In basic training when others were losing weight and gaining muscle, I was getting fat just from eating three normal meals a day. I can tell you it wasn't from lack of activity for sure, just a different metabolism.
Also the less a person eats, the more the stomach shrinks and the more the appetite will wane. So if a person goes a while without eating they need to eat frequent small portions until the stomach stretches again to start feeling hungry.