If this morning’s cup of coffee gave you a sudden craving for cherry pie, it’s not necessarily because you still have Twin Peaks on your mind. A new study by a team of Cornell scientists claims there’s actually something in caffeine that disrupts the way the body naturally perceives food’s sweetness. For their paper, published in the Journal of Food Science, researchers inflicted some cruel and unusual punishment: They gave participants coffee, but refused to say whether it was regular or decaf. As it turns out, subjects were actually “unable to estimate” the caffeine content in their respective cups with any accuracy whatsoever. Both groups in the study thought they’d been given fully caffeinated coffees — but only one group thought theirs was less sweet.
Caffeine might pull this stunt off by blocking one of the chemicals that tells the brain you’re tired. Drinking coffee inhibits adenosine receptors, preventing its neuromodulator effect on the body. But adenosine also perks up the taste buds that sense sweets. When the study’s caffeinated participants got tested a second time, 15 minutes after finishing their cups, they reported a solution made of straight-up sucrose was less sweet, as compared to the placebo group. Additionally, caffeine had no effect on subjects’ ability to sense bitter, sour, salty, or umami tastes, the research showed.
One of the authors, Robin Dando, tells the Washington Post that caffeine’s effect is certainly “noticeable,” and manages to persist for at least a while, which suggests your coffee habit might have “a cumulative effect” throughout the day. She also says this phenomenon could explain why drinks at places like Starbucks and Dunkin’ Donuts are so insanely sweet — either market demand is driving them to crank out concoctions that have a full day’s supply of sugar, or the chains are savvily staying up on the latest science about sugar. Either way, the study suggests people trying to curb their sugar intake might want to give a second thought to — this’ll be tough to handle, but here goes — decaf coffee.