A picture may be worth a thousand calories, a new study suggests. Looking at images of high-calorie foods stimulates the brain's appetite control center and results in an increased desire for food, according to the study, which will be presented Monday at The Endocrine Society's 94th Annual Meeting in Houston.
"This stimulation of the brain's reward areas may contribute to overeating and obesity," said the study's senior author, Kathleen Page, MD, assistant professor at the University of Southern California, Los Angeles.
"We thought this was a striking finding, because the current environment is inundated with advertisements showing images of high-calorie foods," she added.
Using functional magnetic resonance imaging, or fMRI, the researchers studied the brain responses of 13 obese, Hispanic young women. Each participant had two fMRI scans as she viewed blocks of images of high-calorie foods, such as ice cream and cupcakes, as well as low-calorie foods, such as fruits and vegetables, and non-food items. After each block of similar images, participants rated, on a scale of 1 to 10, their hunger and their desire for either sweet or savory foods.
Halfway through the scans, participants drank 50 grams of glucose--the amount of sugar in a can of soda--on one occasion and an equivalent amount of fructose on another occasion. These two simple sugars make up both table sugar and high-fructose corn syrup.
Because fMRI measures blood flow to the brain, regions with increased blood flow indicated greater activity, Page explained. The researchers identified which brain regions activated in response to viewing the images and how sugar consumption influenced brain activation and ratings of hunger and appetite.
Reported results showed that simply viewing high-calorie food images activated brain regions that control appetite and reward, unlike pictures of non-foods. Viewing pictures of high-calorie foods also significantly increased ratings of hunger and desire for sweet and savory foods, Page said.
Ratings of hunger and desire for savory foods also were higher after ingestion of either sugar drink. Compared with glucose ingestion, fructose tended to produce greater activation of brain regions involved in reward and motivation for food. "These findings," Page said, "suggest that added sweeteners could be one of the main contributors to the obesity epidemic."
She said they studied obese, Hispanic young women because this group is at "high risk for continued weight gain and obesity."
The National Institutes of Health, National Center on Minority Health and Health Disparities, funded this study.