Our bodies can crave all kinds of food when we're feeling hungry. Researchers have known for nearly a decade that the sensation of hunger is produced by a chemical in the stomach called ghrelin.
"It makes people feel hungry and it makes people eat more," says Dr. Alain Dagher from the Montreal Neurological Institute.
Now, Dagher and his team at the University of Montreal believe that same chemical may affect the way food looks to us as well.
Using an MRI, the group monitored brain activity of volunteers as they viewed various images including food. Then, they injected several subjects with ghrelin.
Compared to subjects with no-ghrelin in their systems, the scans revealed extra activity in a part of the brain associated with visual processing and pleasure -- but only when the pictures of food were displayed.
"What we think is when these areas are more active, food is more appealing and more attractive and this is what hunger is," says Dagher.
In a published report, Dagher also wrote that the ghrelin subjects also remember the food images more vividly.
"So, this also suggests that ghrelin also increases your attention to food cues."
What the team hopes to learn now is whether that brain activity may actually produce a second kind of eating impulse, one based on pleasure rather than hunger, perhaps, unlocking new clues on what causes some people to overeat.