Im not sure about this, so ask in D&S forum, but i think drinking too much water can also lead to problems. Possibly cramping. If you are not eating a whole lot, and are drinking a lot of water, i think i read that it will flush out all the nutrients and minerals that your body needs. So say you are only eating 1500 calories a day, but drinkin nearly 2 gallons of water a day, you might be pissing out more nutrients than you are getting in such few calories.
Im not sure about this, cant remember where i hear it, so maybe you should ask someone in D&S for a better/accurate explination. It could be completley false, but for some reason i think i read that somewhere.
Do you know Liu?