Looking at pictures of hamburgers, cupcakes and other high-kilojoule edibles can trigger cravings for fattening foods, especially if you're drinking something sweet at the time, according to a new study.
Researchers from the University of Southern California found that drinking a sugary beverage while viewing these foods activates appetite and reward centers in the brain, which could play a role in obesity.
"Studies have shown that advertisements featuring food make us think of eating, but our research looked at how the brain responds to food cues and how that increases hunger and desire for certain foods," said the study's principal investigator, Kathleen Page, assistant professor of clinical medicine at the university's Keck School of Medicine.
"This stimulation of the brain's reward areas may contribute to overeating and obesity, and has important public health implications," said Page.
How the study was done
In conducting the study, the researchers measured the brain responses of 13 obese, Hispanic females, aged 15 to 25 years, as they looked at both high-kilojoule and low-kilojoule foods.
Using functional magnetic resonance imaging (fMRI), the women's brains were scanned twice as they viewed images of foods such as hamburgers, cookies, cakes, fruits and vegetables.
After seeing all of the images, they were asked to rate their hunger as well as their desire for sweet or savoury foods.
Halfway through the scans, the women drank 50 grams of glucose, which is similar to drinking a can of sugary soda. In a separate instance, they drank 50 grams of fructose. Glucose and fructose are found in table sugar and high-fructose corn syrup.
"We hypothesised that the reward areas in the women's brains would be activated when they were looking at high-kilojoule foods, and that did happen," said Page. "What we didn't expect was that consuming the glucose and fructose would increase their hunger and desire for savoury foods."
The researchers pointed out that fructose resulted in more intense cravings and hunger among the women than glucose.
Sweeteners affecting cravings
"Our bodies are made to eat food and store energy, and in prehistoric days, it behooved us to eat a lot of high-kilojoule foods because we didn't know when the next meal was coming," Page said.
"But now we have much more access to food, and this research indicates added sweeteners might be affecting our desire for it," she added.
The researchers said they limited the study to Hispanic women because research has indicated women are more sensitive to food cues, and the Hispanic community has a high incidence of obesity and type 2 diabetes.
More studies are needed to explore whether these cravings are due to obesity or genetics, the authors noted.
The study was presented at the Endocrine Society's annual meeting in Houston. Data and conclusions of research presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.
The U.S. National Library of Medicine provides tips on how to tame food cravings.
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