Eating sugar may quiet stress signals in the brain, leading some people to seek comfort by consuming more sweets and making the habit very hard to break, a small study suggests.
In a two-week experiment, 19 women drank three beverages a day sweetened either with real sugar or aspartame, a substitute. Researchers did magnetic resonance imaging (MRI) brain scans to see how the sweets affected the women and found that sugar, but not aspartame, triggered activity in a part of the brain involved in reacting to stress.
The MRI results suggest that sugar may have interrupted the normal response to stress in the hippocampus region of the brain, limiting production of the stress hormone cortisol, said senior study author Kevin Laugero, a nutrition researcher at the University of California, Davis.
"The findings suggest an explanation of how, mechanistically, sugar may positively reinforce its habitual consumption in people experiencing chronic stress," Laugero said by email.
Without the sugar, the researchers might have expected to see a surge in cortisol during the experiment because they gave the women impossibly difficult math problems to complete in their heads – a challenge designed to trigger a stress response – before the MRIs.
But the women who drank beverages sweetened with sugar had MRIs showing significantly higher activity in the hippocampus and lower levels of stress-induced cortisol than the MRIs of women who had aspartame. Normally, acute stress blocks activity in the hippocampus, the researchers write in the Journal of Clinical Endocrinology and Metabolism.
The study is small and only included women. More research is needed to understand how sugar consumption might impact feelings of stress, Laugero said.
It's possible that stressed out people might crave an experience of eating something sweet, rather than just a specific ingredient such as sugar, David Benton, a psychology professor at Swansea University in the U.K., said by email.
"The idea of being attracted to palatable foods in moments of stress is well described, for example chocolate, but this reflects the temperature at which it melts, the flavor of cocoa, mouth feel and a mixture of fat and sugar," said Benton, who wasn't involved in the study.
Generally, though, people who use foods to cope with stress do tend to make indulgent choices, said Julie Rish, a psychologist with the Bariatric and Metabolic Institute at Cleveland Clinic in Ohio.
"People don't crave carrots or celery, they crave chocolate or ice cream," said Rish, who wasn't involved in the study.
While there isn't a single, simple way to short-circuit these cravings in times of stress, it is possible to develop other ways to cope, such as taking a walk, she said. To make it easier to turn to exercise instead of food, it's best to keep tempting treats out of the house.
"Keeping a positive environment makes it harder to make an unhealthy choice and it also helps you to delay a response to the craving," Rish said. "Those cravings peak over 15 to 20 minutes and if you can just delay them and distract yourself for that long the cravings start to come down on their own."