Why some have big dessert after big meal

HOUSTON, June 28 (UPI) -- Ghrelin, a so-called hunger hormone, is the reason why some people have room for a high-calorie dessert after eating a big meal, Canadian researchers say.

Lead investigator Veronique St-Onge, a Ph.D. candidate and principal investigator Alfonso Abizaid of Carleton University in Ottawa, Ontario, said rats lacking ghrelin receptor gene ate less of a sweet treat after a full meal than did rodents whose ghrelin receptor gene was intact.

"Combined with an increasingly sedentary lifestyle, over-consumption of reward-driven foods may be partly responsible for the current obesity epidemic," St-Onge said in a statement. "Ghrelin receptors may represent an important target for obesity treatments."

The researchers used a rat strain in which ghrelin signaling was genetically disrupted by "knockout" of the receptor gene. Specifically, the researchers compared the knockout rats' tendency to eat cookie dough after a meal, compared with that of the control rat strain -- wild-type rats -- which possessed an intact ghrelin receptor gene.

Each group consisted of 10 rats that were allowed free access to their regular rat chow for 4 hours a day until they ate most of their usual daily intake. On the final day of the study, each rat was offered just over 1 ounce of cookie dough during the last hour of feeding.

There was no difference between groups in the amounts of rat chow that they consumed, but knockout rats ate slightly less cookie dough.

"This result supports the idea that ghrelin is involved in reward-based feeding and delays the termination of a meal," St-Onge told The Endocrine Society's 94th annual meeting in Houston.