A new study shows that the hormone dopamine is released two times during a meal: when the food is first ingested and when the food reaches the stomach.

“With the help of a new positron emission tomography (PET) technique we developed, we were not only able to find the two peaks of dopamine release, but we could also identify the specific brain regions that were associated with these releases,” said senior author Dr. Marc Tittgemeyer, head of the Max Planck Institute for Metabolism Research in Cologne, Germany.

“While the first release occurred in brain regions associated with reward and sensory perception, the post-ingestive release involved additional regions related to higher cognitive functions.”

For the study, 12 healthy volunteers received either a palatable milkshake or a tasteless solution while PET data was recorded.

The researchers discovered that the volunteers’ craving or desire for the milkshake was proportionally linked to the amount of dopamine released in particular brain areas at the first tasting. They also discovered that the higher the craving, the less delayed post-ingestive dopamine was released.

“On one hand, dopamine release mirrors our subjective desire to consume a food item. On the other hand, our desire seems to suppress gut-induced dopamine release,” said Dr. Heiko Backes, group leader for Multimodal Imaging of Brain Metabolism at the Institute, who is co-first author on the study with Dr. Sharmili Edwin Thanarajah.

Suppression of gut-induced dopamine release could potentially cause overeating of highly desired food items, the researchers noted.

“We continue to eat until sufficient dopamine was released,” Backes said, adding this hypothesis remains to be tested in further studies.