Caffeine is also a diuretic, which means that it can dehydrate your body. People who drink nothing but highly caffeinated drinks can end up in the hospital after passing out due to severe dehydration.

This amounts to between one and three cups of Joe. According to FDA guidelines, healthy adults should limit caffeine consumption to 400 milligrams max, which equates to around four cups of coffee.

American Academy of Pediatrics says there is no safe amount of caffeine consumption for children under 12, and advises that all children and teens refrain from consuming energy drinks. The most ...