God knows, I don't think I really want to find out tho! There is the small issue of puking up all the food you put into your system, which, given that food is where we get almost 100% of our energy from, can certainly pose a problem...
Small things I've noticed since not purging... Energy, boundless energy (comparitively speaking), glowing, healthy face, good skin, decrease in crazy weight fluctuation (not purging is far less stressful that way if you get the eating habits in order). And the ability to look people in the eye in worth its weight in gold.
Personally, I'd like to be able to synthesize sunlight, like plants. That way I'll need to be watered, but never fed! Makes everything a whole lot easier!