Caffeine Myths #2 - Caffeine causes dehydration - True or False

Myth #2: Caffeine causes dehydration.True: 

Caffeine is a mild diuretic, but “it’s not very pronounced,” says Franz H. Messerli, M.D., a professor of clinical medicine at Columbia University in New York City.

Still, diuretics make you have to pee. The more often you go, the more fluids you lose. And you'll feel more dehydrated because you’re losing more fluids than you’re taking in.

“I wouldn’t drink a double espresso before a run, but would have no problem drinking a 12-ounce Coke,” Messerli explains. That’s because all fluids, even those with caffeine, contribute to the body’s daily fluid total.