You are less likely to smell foods related to your recent diet and help you choose what to eat next–ScienceDaily

However, new research shows that the food you eat just before you pass the bakery can affect your chances of stopping at a sweet treat, not just because you’re full.

Scientists at Northwestern University have found that people are less sensitive to the smell of food, based on the meal they ate just before. So, for example, if you’re snacking on a colleague’s baked goods before a walk, you’re less likely to stop at the sweet-smelling bakery.

A study that “sensory decision-making is biased by motivational status” will be published in the journal on August 26th. PLOS Biology..

Smell regulates what we eat and vice versa.

The study found that participants who had just eaten either cinnamon rolls or pizza were less likely to perceive “meal-friendly” odors, but less likely to perceive inconsistent odors. .. The findings were then supported by a brain scan showing that the activity of some of the odor-processing brains was altered in a similar manner.

These findings show that what we eat regulates our sense of smell in the same way that smell regulates what we eat.

Feedback between food intake and the olfactory system can provide evolutionary benefits, said Thorsten Kahnt, senior and corresponding research author, assistant professor of neurology, psychiatry and behavioral science at Northwestern University’s Fineberg School of Medicine. Said.

“Given that our ancestors roam the woods trying to find food, they find and eat berries, and then they are less sensitive to the smell of berries,” Khant said. “But perhaps they are still sensitive to the smell of mushrooms, so in theory they could help promote a variety of food and nutrient intakes.”

While Kant has not seen adaptation of the hunter-gatherer community in his daily decisions, the relationship between our nose, what we are looking for, and what we can detect with our nose remains very high. I said it might be important. For example, if the nose is not functioning properly, the feedback loop can be interrupted, causing eating disorders and obesity problems. There may even be a link to sleep disorders, another link to the sensory system that Kant Institute is studying.

Kahnt Labs uses brain imaging, behavioral testing, and non-invasive brain stimulation to study how the sense of smell associated with mental states, especially obesity, addiction, and dementia, guides learning and appetite behavior. increase. In previous studies, the team found that the brain’s response to sleep-deprived participants’ odors was altered, and then whether food intake altered their ability to perceive food odors, and how. I wanted to know if I could change it.

According to Laura Shanahan, a postdoc in the Kahnt lab and the first co-author of the study, there is little research on how odor perception is altered by a variety of factors. “There are some studies on odor comfort, but our work focuses on how sensitive we are to these odors in different conditions,” Shanahan said.

Pizza and pine; cinnamon and cedar

To carry out the study, the team developed a new task of presenting participants with a scent that is a mixture of food and non-food scents (either “pizza and pine” or “cinnamon rolls and cedar”). .. “Pair well” and distinguish from each other). The ratio of food to non-food odors was different for each mixture, from pure food to pure non-food. After the mixture was presented, participants were asked if the odor of food or non-food was dominant.

Participants completed the task twice within the MRI scanner. First when you’re hungry, then after eating a meal that matches one of the two odors.

“In parallel with the first part of the experiment being performed on the MRI scanner, I was preparing a meal in another room,” Shanahan said. “I wanted to eat as much as I could until the participants were full, so I wanted to keep everything fresh, ready and warm.”

The team then calculated the amount of food odor required for the mixture in each session in order for participants to recognize that food odor was dominant. The team found that when a participant was hungry, the proportion of food odor in the mixture needed to be reduced in order to recognize that it was dominant-for example, the hungry participant, You may need 50% cinnamon rolls in the cedar mixture when you are hungry, but 80% cinnamon rolls when you are full.

The team provided further evidence of the hypothesis through brain imaging. Brain scans from MRI showed parallel changes that occur in the parts of the brain that process odors after a meal. The brain’s response to dietary odors was less “food-like” than the response to dietary odors.

Apply findings to future sleep deprivation studies

The results of this study allow the Kernt Institute to work on more complex projects. Kant said he would bring the project back to full sleep deprivation to better understand the feedback loop between the sense of smell and food intake and to see if sleep deprivation could somehow impair the loop. He said he wanted. He added that in brain imaging, there are more questions about how adaptation affects sensory and decision-making circuits in the brain.

“After a meal, the olfactory cortex no longer represents a food-matched odor as much as food, so adaptation seems to occur relatively early in the process,” Khant said. “We are following up on how that information is modified and how the altered information is used by other parts of the brain to make decisions about food intake. . “

This study was funded by the National Institute of Cardiopulmonary Blood (Grant T32HL007909), the National Institute of Diabetes, Gastroenterology and Kidney Disease (Grant R21DK118503), and the National Institute of Hearing Loss and Other Communication Disorders (Grant R01DC015426). ) Provided by.