Iced coffee hits the spot on hot summer days. But if you're looking to get the most pep from a single cup, hot coffee is the way to go, even when it's sweltering. It makes sense when you think about it: If you're choosing between a 16-ounce hot or iced coffee, the latter is about 30 percent ice (a.k.a. water). Chemistry is on #TeamHotCoffee too—brewing coffee at hot temperatures extracts more caffeine from the beans. So if you really want iced coffee, make sure it was brewed hot and then iced, or opt for cold brew, which has twice as many beans, for a stronger caffeine kick.
(h/t Science of Us)