High-fat diets may spur overeating, mouse study suggests

August 15, 2013 by Brenda Goodman, Healthday Reporter

High-fat diets may spur overeating, mouse study suggests
Chips are stacked against would-be healthy eaters, expert says.
(HealthDay)—Many people who have tried to give up fatty foods in favor of healthier choices have found themselves obsessing over cookies or chips. Choosing a salad over a cheeseburger can feel like a Herculean act of will.

Now scientists believe they've found an important clue about why this happens.

Working in , researchers say they've discovered how the gut talks to the reward centers of the brain, and how high-fat diets can jam this communication, potentially leading to overeating and obesity.

The study, which was published online Aug. 15 in the journal Science, also found that high-fat diets actually led mice to turn up their noses at their normal, low-fat chow.

"The implications to humans are huge," said Paul Kenny, a professor of at the Scripps Research Institute in Jupiter, Fla.

"You're trying to lose weight. You have a bad diet and you're trying to adjust it, [but] your body and brain in concert are saying, 'No, I don't want that type of food,'" said Kenny, who was not involved in the research. "The chips are stacked against you—literally, . And that's why you're very likely to fail."

Eating food—especially food high in fat—triggers the release of the feel-good brain .

Previous studies have found that as people and mice become obese, the brain's stops working properly. Eating becomes less rewarding.

As food becomes less stimulating, one theory holds that people need to eat more and more to feel satisfied—creating a of and .

But researchers have never really understood why or how this happens, or, crucially, how to stop it.

For the new study, researchers studied two groups of mice. The first group was fed a normal, low-fat diet. The second group was put on a high-fat diet. Researchers fed the mice through that ran directly into their stomachs to eliminate any influence from the taste or chewing of the foods.

As expected, the mice consuming a high-fat diet made less dopamine in their brains. But surprisingly, they also made less of a lipid (fat) signal called oleoylethanolamine (OEA) in their intestines.

OEA plays an important role in digestion, said the expert who first identified the signal.

"It prevents the excessive eating of fat," said Daniele Piomelli, a professor of anatomy and neurobiology at the University of California, Irvine.

When the researchers gave the mice on the high-fat diet an infusion of OEA, they also made more dopamine in their brains, suggesting that the signal also plays an important role in the reward value of food.

"The fact that this compound is connected with the reward centers of the brain is beautiful and makes sense because all survival mechanisms depend on reward," said Piomelli, who was not involved in the current study.

When humans hunted and gathered their food, it would have made sense for fat to be highly rewarding to the brain.

"Fat is in such short supply in nature. Not in our refrigerators, but in nature it is," Piomelli said. "It is very important for the body to be able to eat the small amounts it finds in the wild and to be able to absorb it completely. That's what this compound does."

Now that dietary fat is hard to escape, this ancient feedback loop may be working against humans.

"We do know that people who have problems making the lipid signal OEA tend to become more morbidly obese," Piomelli said.

But the study also shows there may be hope on the horizon for frustrated dieters.

Mice on a high-fat diet given infusions of OEA lost weight and started to show more interest in low-fat food, suggesting that the compound makes the brain more sensitive to smaller amounts of calories in the gut, said researcher Ivan de Araujo, an associate professor of psychiatry at Yale University.

Experts say, however, that results from animal studies often don't turn out the same in humans.

Whether medications that boost OEA might one day help cottage cheese become as rewarding to the human brain as cheesecake remains to be seen.

"We don't know whether this can successfully be translated into humans," he said.

Explore further: Could ending your fatty food habit cause withdrawal symptoms and depression?

More information: To learn more about healthy eating, head to the U.S. National Heart, Lung, and Blood Institute.

Paper: "A Gut Lipid Messenger Links Excess Dietary Fat to Dopamine Deficiency," by L.A. Tellez et al Science, 2013.

Related Stories

Could ending your fatty food habit cause withdrawal symptoms and depression?

December 12, 2012
Even before obesity occurs, eating fatty and sugary foods causes chemical changes in the brain, meaning that going on a diet might feel similar to going through drug withdrawal, according to a study published today by Dr. ...

Increased production of neurons in hypothalamus found in mice fed high fat diets

March 26, 2012
(Medical Xpress) -- A research team made up of people from a wide variety of biological sciences has found that mice fed a diet high in fat tend to see an increase in the number of neurons created in the hypothalamus, a region ...

Is there a link between childhood obesity and ADHD, learning disabilities?

February 19, 2013
A University of Illinois study has established a possible link between high-fat diets and such childhood brain-based conditions as attention deficit hyperactivity disorder (ADHD) and memory-dependent learning disabilities.

Researchers discover gene that causes obesity in mice

March 5, 2013
Researchers have discovered that deleting a specific gene in mice prevents them from becoming obese even on a high fat diet, a finding they believe may be replicated in humans.

High-fat diet may cause change in hypothalamus

September 11, 2012
(Medical Xpress)—A high fat diet may damage the part of the brain that controls appetite and energy expenditure which in turn dictates our weight.

A maternal junk food diet alters development of opioid pathway in the offspring

July 30, 2013
Research to be presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior, shows that eating a junk-food diet ...

Recommended for you

New inflammation inhibitor discovered

November 16, 2018
A multidisciplinary team of researchers led from Karolinska Institutet in Sweden have developed an anti-inflammatory drug molecule with a new mechanism of action. By inhibiting a certain protein, the researchers were able ...

Gut hormone and brown fat interact to tell the brain it's time to stop eating

November 15, 2018
Researchers from Germany and Finland have shown that so-called "brown fat" interacts with the gut hormone secretin in mice to relay nutritional signals about fullness to the brain during a meal. The study, appearing November ...

Brain, muscle cells found lurking in kidney organoids grown in lab

November 15, 2018
Scientists hoping to develop better treatments for kidney disease have turned their attention to growing clusters of kidney cells in the lab. One day, so-called organoids—grown from human stem cells—may help repair damaged ...

How the Tasmanian devil inspired researchers to create 'safe cell' therapies

November 15, 2018
A contagious facial cancer that has ravaged Tasmanian devils in southern Australia isn't the first place one would look to find the key to advancing cell therapies in humans.

Researchers discover important connection between cells in the liver

November 15, 2018
University of Minnesota Medical School researchers have made a discovery which could lead to a new way of thinking about how disease pathogenesis in the liver is regulated, which is important for understanding the condition ...

Precision neuroengineering enables reproduction of complex brain-like functions in vitro

November 14, 2018
One of the most important and surprising traits of the brain is its ability to dynamically reconfigure the connections to process and respond properly to stimuli. Researchers from Tohoku University (Sendai, Japan) and the ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

cardiacguy
not rated yet Aug 15, 2013
Guess I'm missing the mouse gene. When I eat a cheeseburger I feel full. When I eat a salad, I want a cheeseburger.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.