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Why We Reach for Sugar When We're Stressed

Those sweets have a uniquely calming effect on stress, according to new research.
(Photo: tomatoes and friends/Flickr)

(Photo: tomatoes and friends/Flickr)

There may be a reason why "comfort foods" are so stuffed with carbohydrates: Scientists have recently discovered that pure sugar reduces the stress hormone, cortisol, in a way that artificial sweeteners, like aspartame, do not.

"These experimental findings support a metabolic-brain-negative feedback pathway that is affected by sugar and may make some people under stress more hooked on sugar and possibly more vulnerable to obesity and its related conditions," the researchers write in their study, published earlier this month in the Journal of Clinical and Endocrinology and Metabolism.

In the study, the research team looked at fMRI scans of participants solving difficult math problems. One group was fed sugar and another aspartame. The researchers found that those fed sugar showed a significant difference in the parts of the brain responsible for producing fight-or-flight responses, and a subsequent increase in cortisol found in their saliva—a common way of measuring stress.

The researchers found that those fed sugar showed an increase in cortisol found in their saliva—a common way of measuring stress.

This helped the researchers discover why sugar puts us in such a dangerous cycle of over-eating. Unlike normal stress events, sugar stimulates the production of insulin, a hormone responsible for storing energy in fat and muscle. "If the source of stress is not removed," the authors write, "continued self-medication in this fashion might lead to central obesity."

Hence, with sugar, we eat, calm down, gain weight, don't eliminate the source of stress, and continue the cycle until we've eaten the entire box of Thin Mints (not that I'm speaking from personal experience).

This latest research coincides with the increasingly common finding that sugar is an addictive chemical. "In some circumstances, intermittent access to sugar can lead to behavior and neurochemical changes that resemble the effects of a substance of abuse," one 2007 study on addictive behavior in sugar-fed rats concluded. The authors of that study found that the intermittent way humans feed on sugar produces a vicious dependency cycle of binging, withdrawal, and craving.

Sugar's unique role in addiction and obesity have led some doctors to argue that it should be regulated as a controlled substance. Among the most vocal proponents is University of California-Los Angeles' Robert Lustig. "Food should confer wellness, not illness. The industry feeds our sugar habit to the detriment of our society. We need food purveyors, not food pushers," Lustig wrote in the Atlantic last year, arguing that sugar meets all the legal standards of a drug. Neurological addiction, he claimed, is a non-essential nutrient, and causes significant social harms.

Whether or not such regulation arrives, it still might be helpful to know why we reach for sugary comfort foods. As it turns out, they can calm us down. But, in the end, they still cause more harm to our bodies than the temporary relief that a doughnut is worth.

Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.