When you put it that way, I'm terrified

I'll never drink again, honest:

According to studies, drinking about 250 milliliters of an alcoholic beverage causes the body to expel 800 to 1,000 milliliters of water; that's four times as much liquid lost as gained. This diuretic effect decreases as the alcohol in the bloodstream decreases, but the aftereffects help create a hangover.

The morning after heavy drinking, the body sends a desperate message to replenish its water supply -- usually manifested in the form of an extremely dry mouth. Headaches result from dehydration because the body's organs try to make up for their own water loss by stealing water from the brain, causing the brain to decrease in size and pull on the membranes that connect the brain to the skull, resulting in pain.