When you need that afternoon pick-me-up, you instinctively grab a cup of joe. But does drinking that cup of coffee also make you grab a bag of chips, too, because it's giving you the munchies? The jury's still out on whether java has the same hunger-inducing properties as, say, marijuana, but several studies provide conflicting information about whether caffeine actually increases or decreases appetite.
For example, a 2014 study conducted by researchers in Germany and Austria seems to show caffeine curbs hunger. The study was small, and included just 84 people, who over the course of four weeks drank two different coffee blends with similar caffeine contents.
The study found that one of the two coffee blends increased the participants' serotonin, a hormone that curbs appetite and blocks neurons that increase appetite — and also decreased ghrelin, a hormone that increases appetite. Study participants also lost body fat over the four weeks.
But another 2016 study published in the journal Appetite and conducted by researchers at State University of New York using mice showed doses of caffeine increased the food the mice ate, leading researchers to conclude caffeine increases appetite.
Finally, another 2014 study conducted by researchers at the School of Allied Health Sciences at Griffith University in Australia looked at whether mid-morning coffee breaks could curb appetite. It tested both decaf and regular coffee and found caffeine had no impact on hunger, though the researchers felt the topic needed more research.
So while scientific evidence is up in the air, most signs seem to show that caffeine helps to suppress your appetite, not encourage it. That could explain why many over-the-counter appetite suppressants contain caffeine.
But don't use that as a license to order with abandon at your favorite coffee shop. Remember, a lot of those coffee-based beverages have added sugar, cream and other ingredients that add calories and fill you up.