Sugar Trumps Fat in Triggering Cravings

An Irish Car Bomb cupcake
An Irish Car Bomb cupcake
Malcolm Bedell/From Away

Doughnut or bacon? What do people crave more, sugar or fat? Is it that sweet taste or that creamy texture? Or, perhaps, both (bacon doughnut)?

According to a new study, the answer is unequivocably: sugar. Congratulations, sugar! You win prom queen.

Scientists tracked the brain activity in more than 100 high school students as they drank chocolate milkshakes that had the same calories but were either high in sugar and low in fat or vice versa, The New York Times reports.

Brain MRI scans revealed that both kinds of shakes lit up the pleasure centers in the brain, but those that were high in sugar did so far more spectacularly. In fact, they stimulated a neural food-reward network that plays a role in compulsive eating.

Surprisingly, sugar even trumped a combo of sugar and fat. High-sugar, low-fat shakes stimulated the reward circuitry just as strongly as shakes that mixed sugar and fat in large quantities. The study was funded by the National Institutes of Health and published in The American Journal of Clinical Nutrition.

"We do a lot of work on the prevention of obesity, and what is really clear not only from this study but from the broader literature overall is that the more sugar you eat, the more you want to consume it," Dr. Eric Stice, the study's lead author and a senior research scientist at the Oregon Research Institute, told the NYT. "As far as the ability to engage brain reward regions and drive compulsive intake, sugar seems to be doing a much better job than fat."

According to recent brain studies, processed foods high in fat and sugar (and salt) activate and may even change the same reward regions in the brain that are affected by alcohol and illicit drugs, provoking addictive behavior. This might help explain why millions of people have such trouble sticking with diets and losing weight. People don't overindulge in fruits, vegetables and grains. They eat too much sugar, fat and salty foods. But of the three, sugar appears to be the most addictive.

In the latest study, Dr. Stice and his colleagues had 106 healthy, "lean" teenagers sip different milkshakes while lying in MRI machines (tough study).

All of the milkshakes were made with chocolate syrup and ice cream. But some contained half and half while others had 2 percent milk, and some were made with more simple syrup than others.

The researchers found that low-fat, low-sugar milkshakes activated regions of the brain associated with taste and sensation, but did absolutely nothing to reward regions.

High-fat, low-sugar milkshakes (9 grams of fat and 7 grams of sugar per 100 milliliters) stimulated part of the reward circuitry. A high-sugar, low-fat shake hit the brain just right: with triple that amount of sugar but only a quarter of the fat, such brain structures as the putamen, insula and rolandic operculum lit up like a Christmas tree.

These brain regions, called the food-reward system, control the desire for food. The more active they are, the more we want to eat. And when we binge and a high-sugar food is then taken away, we can experience withdrawal symptoms similar to opiate withdrawal. When researchers tried increasing the fat content of the high-sugar shake, it didn't activate the reward region any further.

Stice said that the human brain is hardwired to prefer sweetness, noting how much children prefer high-sugar foods from the get-go. "We develop preferences for fat, but we're basically born with a preference for sugar," he told the New York Times.

Stice said all of the evidence points to sugar as the big obesity culprit in the U.S.: "If you look at our American diet, most people are consuming considerably more sugar than fat," Stice said. Fat is whack, but obesity policy, prevention and treatment should target that demon sugar, he says.

Could that mean methadone for cupcake addiction?

Want more Squid Ink? Follow us on Twitter or like us on Facebook, and follow Samantha Bonar at @samanthabonar.

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