Following a hearty holiday dinner, many find themselves satiated, lethargic, and a little tight in the waistband. Nevertheless, this doesn’t stop us from devouring a generous serving of apple pie, or downing a glass of creamy eggnog. Despite having stuffed yourself to the limit, why is there always room for dessert?
Ghrelin, a hormone in the stomach responsible for stimulating appetite, is partly accountable. Hungry or not, ghrelin causes the brain to be more receptive to visual cues, such as appealing desserts. The brain responds and relays the sensation back to the stomach, often translating to the signal that stimulates appetite. For people with a sweet tooth, this craving is hard to resist.
Dr. Jay Gottfried of University College London conducted a study of the neurological impact of “selective satiation,” or what he prefers to call “the restaurant phenomenon.” MRIs were performed on 13 volunteers and live brain activity was studied in response to different stimuli. Volunteers were shown computer images while the sweet aromas of ice cream, vanilla, or peanut butter wafted past them.
“At various points before, during, and after scanning we asked them to give us pleasantness ratings for the smells,” said Gottfried. “Unconsciously, the volunteers began to associate the images with the smells.” The images that appeared when a pleasant aroma was present received higher ratings. When the volunteers ate the ice cream or peanut butter, brain images showed a strong emotional response. Additionally, the impact of the olfactory stimulus was weakened. “A person’s response to the peanut butter odour changed after eating some peanut butter, but a vanilla smell made the brain light up again. Eventually, the abstract picture associated with vanilla evoked the responses, but again they weakened after the volunteers ate,” explained Gottfried.
The study found that the amygdala—the area of the brain that processes emotions—and the orbitofrontal cortex were stimulated in response to the sweet aromas. Damage to either of these regions could cause Kluver-Bucy syndrome, whereby patients consume large amounts of food or attempt to eat non-food items. Abnormalities in these regions are speculated to have a role in over-eating disorders.
Another study conducted at Queen’s University suggests a somewhat bizarre alternative. William Ruddock and his colleagues investigated the hypothesis of an accessory dessert pouch either in, or attached to the stomach. While this pouch would not be localized in any anatomical record, Ruddock and his colleagues used a dessert-like substance termed chocoglucofructogalactomaltolactosucrografin (or Fudge-o-grafin) in an attempt to visualize it. Study subjects were winners of pie-eating contests who claimed to always have room for dessert. The results showed that there was a hollow out-pouching from the antrum of the stomach, ranging from 150 to 1600 mL in size, which they called the “Pot de Crème.”
