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Ideas | Kelly Kasulis

Why coffee makes you overeat sweets

David L. Ryan/Globe Staff/File

Cultures around the world have always enjoyed sugary treats with their coffee. People of the Ottoman Empire ate baklava with theirs, while several European countries have a version of the “coffee cake.”

A recent study may explain why the pairing works so well.

Food scientists at Cornell University served decaf coffee to two different groups — one drank the coffee as is, while the other had 200 milligrams of caffeine added to their cups.

Both groups had a controlled amount of sugar in their drinks, but those who drank the caffeinated version rated their coffee as less sweet. That’s because adenosine receptors in our taste buds — which are known to boost sweet flavors — are probably tempered by caffeine.


“Our sense of taste isn’t this set-in-stone measure. People think taste is like your eyesight,” said Robin Dando, an assistant professor at the Department of Food Science at Cornell University and the study’s senior author. “But we’re affected by the things we consume and encounter, and what state we’re in at the time that we perceive taste.”

In previous research, Dando and his colleagues found that humans crave sweet treats even more when caffeine weakens their ability to taste it — which isn’t comforting news if you’re on a diet. The average American drinks about three 9-ounce cups of coffee a day, according to the Harvard T.H. Chan School of Public Health, and mostly during breakfast or between meals.

“We see a decreased sweetness sensitivity, and ultimately that is going to drive people’s motivation to have more sweet foods with their coffee,” said Christopher Simons, an assistant professor of food science and technology at Ohio State. “This could be a very real interaction that impacts our nutrition and food intake.”

The study had another insight: Participants couldn’t tell whether they were drinking a decaf cup of coffee or not. And both groups generally reported that the drink made them more alert. It’s a classic case of the placebo effect: Just the smell and taste of coffee makes us think we’re raising our energy levels.


Simply put, we might not need those extra cups of caffeine as much as we think.

“The real takeaway of all this is that our taste is more complex than we give it credit for, so we need to be a little bit mindful of it,” Dando said. “If we pay attention to our cravings a little too much, then we can end up doing things that we really shouldn’t be.”

Kelly Kasulis is a freelance journalist. Follow her on Twitter: @KasulisK.