Excessive drinking greatly inhibits production of ADH, anti-diuretic
hormone, which causes the kidneys to reabsorb water. Because of this, you become dehydrated, lose your salt balance of sodium and potassium, lose your water soluble b-vitamins. And since you are less hydrated, your blood pressure shoots up, your brain shrinks in size(not very much but it does because of the dehydration), and your skin doesn't look so great.