By Janice Wood
New research finds that television food commercials disproportionately stimulate the brains of overweight teenagers, including the regions that control pleasure, taste, and the mouth.
The findings from the Dartmouth College study suggest the commercials mentally simulate unhealthy eating habits. This could make it difficult for the teens to lose weight later in life, say researchers.
Researchers add that dieting efforts should not only target the initial desire to eat tempting food, but subsequent thinking about actually tasting and eating it.
For the study, which was published in the journal Cerebral Cortex, the researchers used functional magnetic resonance imaging to examine brain responses to two dozen fast food commercials and non-food commercials in overweight and healthy-weight adolescents between the ages of 12 and 16.
The commercials were embedded within a popular television show, “The Big Bang Theory,” so the teens were unaware of the study’s purpose, the researchers noted.
The results show that in all the adolescents, the brain regions involved in attention and focus — occipital lobe, precuneus, superior temporal gyri, and right insula — and in processing rewards — nucleus accumbens and orbitofrontal cortex — were more strongly active while viewing food commercials than non-food commercials.
Also, teens with higher body fat showed greater reward-related activity than healthy weight teens in the orbitofrontal cortex and in regions associated with taste perception, according to the study’s findings.
The most surprising finding was that the food commercials also activated the overweight adolescents’ brain region that controls their mouths, the researchers said. This region is part of the larger sensory system important for observational learning, the scientists noted.
“This finding suggests the intriguing possibility that overweight adolescents mentally simulate eating while watching food commercials,” said lead author Kristina Rapuano, a graduate student in Dartmouth’s Brain Imaging Lab.
“These brain responses may demonstrate one factor whereby unhealthy eating behaviors become reinforced and turned into habits that potentially hamper a person’s ability lose weight later in life.”
Although previous studies have shown heightened brain reward responses to viewing appetizing food, the Dartmouth study is one of the first to extend this relationship to real world food cues — for example, TV commercials for McDonald’s and Burger King — that adolescents encounter regularly, the researchers said.
The brain’s reward circuitry involves the release of dopamine and other neurotransmitter chemicals that give pleasure and may lead to addictive behavior, they add.
Children and adolescents see an average of 13 food commercials each day, so it isn’t surprising they show a strong reward response to food commercials, the researchers said.
But the new findings that these heightened reward responses are coupled with bodily movements that indicate simulated eating offer a clue into a potential mechanism on how unhealthy eating habits are developed, they noted.
“Unhealthy eating is thought to involve both an initial desire to eat a tempting food, such as a piece of cake, and a motor plan to enact the behavior, or eating it,” Rapuano said.
“Diet intervention strategies largely focus on minimizing or inhibiting the desire to eat the tempting food, with the logic being that if one does not desire, then one won’t enact.
“Our findings suggest a second point of intervention may be the somatomotor simulation of eating behavior that follows from the desire to eat. Interventions that target this system, either to minimize the simulation of unhealthy eating or to promote the simulation of healthy eating, may ultimately prove to be more useful than trying to suppress the desire to eat.”
Source: Dartmouth College
Photo Credit: Kristina Rapuano