It’s no secret that Americans love coffee — more than 60 percent of us drink it on a daily basis. For the bulk of the population, it’s the most popular way to get that much-needed morning caffeine boost, followed by tea and soda. And while caffeine has been a cultural cornerstone for centuries, an increasing number of weight-loss supplements contain caffeine, often characterizing it as an appetite suppressant. But can caffeine really curb hunger?