(YouBeauty)

The science of why you have a second stomach reserved for sweet treats.

“What a great meal—I’m stuffed! Dessert? Of course, I have room for dessert.” Sound familiar?We always seem to have room for dessert? It goes back to the days of our ancestors, explains Alfonso Abizaid, Ph.D., a professor of neuroscience at Carleton University in Ottawa, Ontario. “We have evolved to detect and consume foods that are high in caloric content because our ancestors survived food shortages by over-consuming foods, particularly those high in fat and sugars, when those were available,” he says. “We also evolved to really like and seek out these foods in spite of not being hungry, as the extra pounds gained from overeating when food was plentiful may have saved our ancestors’ lives when food was scarce.”

In a nutshell: Caveman-You really needed those Oreos, but Today-You? Not so much. Still, it takes discipline to fight the primal instinct to eat high-fat, high-calorie foods. And judging by the fact that more than one-third of American adults are obese today, it’s clear that many of us are losing that battle.

Dr. Abizaid and his team worked on a study based on the knowledge that the hormone ghrelin—dubbed “the hunger hormone” because it is released when people are hungry or stressed—increases the desire for additional calories, even after a full meal has been consumed. The experiment was done on normal rats and a group of rats that had a mutation to their ghrelin receptors.

Here’s how it went down: Both groups of rats were placed on a scheduled diet with access to food for just four hours per day. They learned to eat most of their required calories during this time. In short, they pigged out. In the “dessert” test, all of the rats ate a bunch of regular food for hours—both groups were equally gluttonous. After the four-hour meal, however, the rats were all given access to some yummy cookie dough. The normal rats ate it avidly, despite the fact that they were full. The rats with the mutation to their ghrelin receptor ate significantly less cookie dough.

What does this mean for your post-dinner Ben & Jerry’s habit? “Not having a receptor for ghrelin—hence being ghrelin insensitive—makes animals less likely to engage in hedonic feeding and eat less in spite of the availability of yummy treats,” explains Abizaid. “Perhaps drugs that block ghrelin receptors can be used to control hedonic feeding in humans who have difficulties controlling their caloric intake, especially if taken just before a meal.”

Until that miracle pill comes, however, we’re stuck with exercising some self-control when we’re full and dessert is offered. “Despite the intensity of any craving, it’s possible to change your preferences for certain foods if you eat less of those foods,” says Elisa Zied, R.D. In a pinch, Zied recommends distracting yourself from dessert cravings with a regular after-dinner walk or popping a mint in your mouth after a meal.