A new study published in Gastroenterology examined how carbonation changes the way our brains perceive sweetness. The researchers looked at magnetic resonance imaging to see what parts of the brain were lighting up during consumption of diet and regular soda. Here’s what they found: regardless of whether the beverage contained sugar or an artificial sweetener, regions that influence the ways we detect sweetness lit up like crazy. Carbonation, the researchers concluded, might be responsible for leveling the playing field between the sweeteners. “Carbonation seems to change the way that we detect sweetness,” said Catia Sternini, MD, professor of medicine at UCLA’s David Geffen School of Medicine. “It looks like it tricks the brain.” That might explain why both camps of fizz fanatics—diet soda and regular—have such strong adherents. “It has been shown before that the brain actually perceives the sweetness [of sugar and artificial sweeteners] differently, but then the carbonation makes it pleasant,” Dr. Sternini said. “If you feel pleasant, they’re both perceived similarly.” Researchers can’t yet explain exactly how CO2 manages to pull off this magic trick, but it probably sounds like great news to diet soda drinkers. After all, if carbonation fools your brain into thinking it’s getting sugar, you can guzzle free of calories and guilt. Then again, this study might also help explain why diet soda consumption is linked to obesity and metabolic syndrome. “The brain might think that because it doesn’t get enough calories or the carbohydrates it needs for energy, you might feel like you need to eat more,” Dr. Sternini said. “It’s just speculation, but based on all the differences that have been shown, one would think maybe that’s what’s happening.”
