June 26, 2012
If You See It, Do You Crave It?
You're doing your own thing when a food craving suddenly hits. Was it from seeing an image of a cupcake or that can of sugary soda you just finished?
University of Southern California (USC) researchers presented study findings this week at the Endocrine Society´s yearly meeting showing how the appetite and reward centers of the brain are stimulated by seeing images of high-calorie foods.
"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 Kathleen Page, principal investigator and assistant professor of clinical medicine at USC'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."
Page and colleagues used functional magnetic resonance imaging (MRI) to measure the brain responses of 13 obese, Hispanic adolescent women ranging in age from 15 to 25. Women were picked based on prior research showing that they are more receptive to food cues. The study group was narrowed to Hispanic women because of the larger risk of obesity and type 2 diabetes in the Hispanic community.
Women's brain responses were scanned twice as they looked at pictures of high-calorie foods, such as hamburgers, cookies, and cakes, and low-calorie foods such as fruits and vegetables. Subsequent to seeing the high-calorie and low-calorie groupings, the participants rated their hunger and desire for sweet or savory foods on a scale from 1 to 10.
Partway through the scans, the women drank 50 grams of glucose – equivalent to a can of soda – and another time, they drank 50 grams of fructose. Glucose and fructose are the main ingredients of table sugar and high-fructose corn syrup.
"We hypothesized that the reward areas in the women's brains would be activated when they were looking at high-calorie 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 savory foods."
The researchers also shared that fructose stimulated more appetite and craving in the participants' brains than glucose did.
"Our bodies are made to eat food and store energy, and in prehistoric days, it behooved us to eat a lot of high-calorie 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."
Still many questions are unanswered about whether these cravings are environmental (caused by obesity) or genetic. Page's future plans are to study what happens to the brains of obese individuals while they are dieting.