German researchers have proven for the first time what many already assume to be true: the mere sight of delicious food stimulates the appetite.

A study on healthy young men by the Max Planck Institute found that the visual stimulation of food images increases the amount of protein hormone ghrelin in the blood.

As a main regulator, ghrelin controls both eating behaviour and the physical processes involved in food metabolism.

“The findings of our study demonstrate, for the first time, that the release of ghrelin into the blood for the regulation of food consumption is also controlled by external factors,” Max Planck Institute scientist Petra Schüssler said.

“Our brain thereby processes these visual stimuli, and the physical processes that control our perception of appetite are triggered involuntarily. This mechanism could prompt us to eat a piece of cake just two hours after breakfast.”

The study warns that the exposure of food images causing the unnecessary consumption of food is particularly high in advertising-dominated societies.

The publication, External stimuli control the hormonal regulation of our eating behavior, was published January 2012.