Why You’ll Still Have Room for Pie After Turkey and Stuffing
It’s a gastronomic phenomenon that some call the “dessert shelf”: the remarkable ability of many a Thanksgiving eater to feel completely full after the main course, yet still have room for dessert. Of course, the ability to eat sweets on a full stomach isn’t limited to Thanksgiving, but it’s especially apparent after the holiday feast.
What makes this possible? Scientists have long known that a hormone called ghrelin, which is produced by cells lining the stomach, plays a role in inducing appetite. A counterpart hormone called leptin, which produced in fat cells and other types of tissue, suppresses appetite. When levels of ghrelin in the bloodstream are high, we feel hungry; after eating, ghrelin levels drop off and leptin levels increase, signaling to our brain that we’re full. That, anyway, is how it’s supposed to work.
However, a study involving ghrelin-deficient rats published this past summer by researchers from Carleton University in Canada suggests that something else is going on when we are confronted with sweets. Ghrelin could be leading us to eat high-calorie, high-fat foods like pumpkin pie even after our stomachs are full.
In the experiment, the researchers studied 10 normal rats and 10 rats from a special strain that lacked the gene that codes for the brain’s ghrelin receptors. For this group of knockout rats, no matter how much ghrelin their stomachs produced, the brain had no way of registering the hormone and registering that the rat was hungry.
For four days in a row, the researchers gave all of the rats access to standard-grade rat food from 10 a.m. to 2 p.m. Both groups of rats ate roughly the same amount of food, which provided enough calories to give them sufficient energy to go about their day.