By baffling the brain, saccharin and other sugar-free sweeteners — key weapons in the war on obesity — may paradoxically foster overeating.
At some level, the brain can sense a difference between sugar and no-calorie sweeteners, several studies have demonstrated. Using brain imaging, San Diego researchers now show that the brain processes sweet flavors differently depending on whether a person regularly consumes diet soft drinks.
“This idea that there could be fundamental differences in how people respond to sweet tastes based on their experience with diet sodas is not something that has gotten much attention,” says Susan Swithers of Purdue University in West Lafayette, Ind. A key finding, she says: Brains of diet soda drinkers “don’t differentiate very well between sucrose and saccharin.”
Erin Green and Claire Murphy of the University of California, San Diego and San Diego State University recruited 24 healthy young adults for a battery of brain imaging tests. Half reported regularly drinking sugar-free beverages, usually at least once a day. The rest seldom if ever consumed such drinks. While the brain scans were underway, the researchers pumped small amounts of saccharin- or sugar-sweetened water in random order into each recruit’s mouth as the volunteer rated the tastes.