Effects of water intake on the fluid balance of the body?

Answer 1

As your body becomes saturated your cells swell up with the water. If you are slightly or severely dehydrated, your cells shrink, but when you drink water they "plump" back up to a healthy size and are able to exchange gases (like oxygen and carbon dioxide), amino acids (proteins in your food and in your body), and hormones productively again. This is one reason why people feel tired when slightly dehydrated and a simple glass of water can perk them up.

But if interested, one can actually overhydrate their body and drown from the inside out because cells will burst when oversaturated and it is possible to burst too many. Most people do not need to worry about this at all, though, because most people do not drink enough water and are slightly dehydrated much of the time.