Thanks for saving me the trouble of posting the same exact question! I have been sick, barely able to eat 500 calories a day (because I'm sleeping for most of it) but I haven't had many liquids either. I got on the scale this morning thinking something good might come from being ill but all I saw was a 1.5 pound gain! Grrr! Im thinking (HOPING!) it is water retention too because I just can't imagine my metabolism shutting down after only a couple days of eating very little. But maybe it can? No idea. I'm looking forward to more responses.
Hope you are feeling better!