Roasting beans decreases their level of caffeine, so strong, bold, darkly roasted coffees contain less than light and medium roasts, by volume. But the longer they’re roasted, the less coffee beans weigh. So if you buy a cup from a coffee house that measures by weight it’ll require more dark beans and pack a bigger caffeine punch. Another surprising fact about dark roasts: They cause less acid production, making them easier on your stomach.
READ MORE: The Benefits of Coffee vs. Tea