Hydration is very important, but the idea that eight glasses of water is essential is a strange one.

In healthy people, researchers have not found any connection between fluid intake and kidney disease, heart disease, sodium levels, or skin quality.

But water is a calorie-free alternative to other beverages (especially sugary ones like soda or sports drinks), and people who drink water instead of those beverages consume fewer calories overall.

A good rule is to drink when you're thirsty — you don't need to count the glasses.