Follow for more talkers

Scientists identify where the craving for fatty foods comes from

"The overconsumption of fats and sugars is causing an epidemic of obesity."

Avatar photo

Published

on
A takeout dish of french fries with chili and cheese surrounded by hotdogs on a wooden table
(Toasted Pictures via Shutterstock)

By Mark Waghorn via SWNS

A brain 'switch' that makes people overeat junk foods has been discovered by scientists at Columbia University.

It fuels cravings for fatty foods - offering hope for new treatments for obesity and binge eating.

The taste of butter, fries or ice cream can be hard to resist. Turning off the circuit may hold the key.

It connects fat sensors in the gut with neurons in grey matter. A signal is carried along nerves- driving our desire for unhealthy foods.

First author Dr. Mengtong Li, of Columbia University, New York, said: "We live in unprecedented times, in which the overconsumption of fats and sugars is causing an epidemic of obesity and metabolic disorders."

"If we want to control our insatiable desire for fat, science is showing us that the key conduit driving these cravings is a connection between the gut and the brain."

The study in the journal Nature raises the possibility of breaking the link - combating the growing global health crisis caused by overeating.

via GIPHY

It builds on the team's previous work on sugar. They found a similar reaction in response to intestinal sugar.

Calorie-free artificial sweeteners, on the other hand, did not have the same effect - shedding light on why diet drinks can leave us feeling unsatisfied.

Co-author Professor Charles Zuker said: "Our research is showing the tongue tells our brain what we like, such as things that taste sweet, salty or fatty.

"The gut, however, tells our brain what we want, what we need."

In experiments, Dr. Li offered mice bottles of water laced with dissolved fats - either components of soybean oil or tasty sweet substances known to not affect the gut.

Over a couple of days, the lab rodents developed a strong preference for the formula- even those genetically modified so they could not taste fat with their tongue.

Dr. Zuker said: "Even though the animals could not taste fat, they were nevertheless driven to consume it."

The researchers reasoned behavioral responses to fat were being triggered by specific brain circuits.

Scans showed neurons in one particular region of the brainstem, the cNST (caudal nucleus of the solitary tract), perked up.

It was also implicated in the earlier discovery relating to sugar preference. Dr. Li then found communication lines that carried the message.

people, fast food, junk-food and unhealthy eating concept - close up of woman with popcorn, nachos or corn crisps and peanuts in bowls
(Ground Picture via Shutterstock)

Neurons in the vagus nerve, which links the gut to the brain, also twittered with activity when mice had fat in their intestines.

She next took a close look at the gut itself - specifically the endothelial cells lining the intestines.

Two groups of cells sent signals to the vagal neurons in response to fat.

Dr. Li explained: "One group of cells functions as a general sensor of essential nutrients, responding not only to fat, but also to sugars and amino acids.

"The other group responds to only fat, potentially helping the brain distinguish fats from other substances in the gut."

She then went a step further by blocking the cells using a drug. Shutting down signaling from either group prevented vagal neurons from responding to fat in the intestines.

Genetic techniques to deactivate either the vagal neurons themselves or the neurons in the cNST had the same effect. In both cases, a mouse lost its appetite for fat.

Dr. Li said: "These interventions verified that each of these biological steps from the gut to the brain is critical for an animal's response to fat.

"These experiments also provide novel strategies for changing the brain’s response to fat and possibly behavior toward food."

The stakes are high. Obesity rates have nearly doubled worldwide since 1980. Today, nearly half a billion people suffer from diabetes.

Dr. Zuker said: "The overconsumption of cheap, highly processed foods rich in sugar and fat is having a devastating impact on human health, especially among people of low income and in communities of color.

"The better we understand how these foods hijack the biological machinery underlying taste and the gut-brain axis, the more opportunity we will have to intervene."

Prof Scott Sternson, of California University in San Diego, who was not involved in the study, highlighted its potential for improving human health.

He said: "This exciting study offers insight about the molecules and cells that compel animals to desire fat.

"The capability of researchers to control this desire may eventually lead to treatments that may help combat obesity by reducing consumption of high-calorie fatty foods."

Stories and infographics by ‘Talker Research’ are available to download & ready to use. Stories and videos by ‘Talker News’ are managed by SWNS. To license content for editorial or commercial use and to see the full scope of SWNS content, please email [email protected] or submit an inquiry via our contact form.

Top Talkers