You can blame too many pieces piece of fried chicken or that all those slices of chocolate cake for those extra pounds you're carrying around, but according to new research a hormone may be contributing to obesity. Simply put, ghrelin, a naturally-occurring molecule found in humans makes that piece of cake look better than it actually is and increases perception and memory with regards to food.

Ghrelin levels flucuate between meals and may cause you to feel hungry and consume more food; scientists were already aware of this fact. But when they studied 20 individuals, some who were injected with ghrelin and some not, they found the ones who received the injections showed stronger reactions to pictures of food they were shown than the participants who had not been injected. Scientists involved in the new study believe this indicates the effect ghrelin has on hunger and obesity.

"When you go to the supermarket hungry, every food looks better," said researcher Alain Dagher, a neurologist at McGill University in Montreal. "Now, we've found that it is ghrelin that acts on the brain to make food more appealing."

"Obesity must be understood as a brain disease," Dagher told LiveScience. "Obese people eat too much, and this is likely due largely to excess hunger."

Unfortunately the treatments developed to supress the effects of ghrelin could have negative side effects such as depression since the hormone is involved in the area of the brain that affects emotion, motivation and addiction to substances such as drugs. Dana Small, a neuroscientists and psychologist from the John B. Pierce Laboratory who was not involved with the ghrelin study, says this new research indicates the facts known about drug addiction could be used in understanding and treating obesity.

It may be reasonable to think "of high-calorie food as having addictive potential," he added. "If food can be thought of as 'addictive,' this supports doing things like banning fast food shops from schools, or advertising junk food to children. Note that public policy aimed at tobacco was really spurred by the science showing that nicotine was addictive."

» MSNBC Health