This worked for me too, I could eat any amounts of anything and weight even less than normal. Then I realized (well, my gastroenterologist did) that my liver had a pretty common pathology all that time and it started to make harm. We quickly fixed that and now I have to choose what to eat, because gaining, say, 5kg in one week is a no-brainer now. This is the story of one specific issue with a human body, that has tens if not hundreds of them.