According to what researchers say, occasional fasting may boost your brain's ability. Why? Because it activates what's often called "the hunger hormone."

Ghrelin is a hormone primarily released in the stomach that signals to the brain that you're hungry. Researchers generally believe that ghrelin levels increase during times of fasting when you're hungry and usually drop several hours after eating, according to WebMd.

But Jeffrey Davies, an associate professor of molecular neurobiology at Swansea University in the U.K., says ghrelin does more than signal hunger. Davies has published several studies on the power of ghrelin and says the hormone can stimulate the growth of brain cells and improve memory in mice.

"The message that mild calorie restriction is beneficial to health is supported by clear evidence," he says. "For the general population that is something that they may be able to introduce into their lives, similar to increasing the amount of exercise they take part in."

One function of the hormone is to respond to changes in the environment, he says. "This ‘homeostatic’ function sees it being released during periods of calorie restriction to activate mechanisms to trigger feeding and restore a healthy metabolic state. As part of this homeostatic response, ghrelin seems to prime other physiological aspects to improve the chances of survival, i.e improving memory function."

His team's work was recently presented at the British Neuroscience Association.