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Why do some foods seem irresistible? The answer is in your gut

In a discovery that could redefine dietary interventions, experts at the Monell Chemical Senses Center have identified neural pathways specifically linked to cravings for fats and sugars. 

The study not only demystifies the internal mechanisms driving our appetite for unhealthy foods, but also raises important questions about how these cravings may hinder dieting efforts.

Gut-brain pathways 

The researchers have found distinct gut-brain pathways that are separately activated by fatty and sugary foods. When these pathways combine, they amplify our desire to eat, potentially leading to overconsumption.

Study lead author Dr. Guillaume de Lartigue described this as a “one-two punch” to the brain’s reward system.

“Food is nature’s ultimate reinforcer,” said Dr. de Lartigue. “But why fats and sugars are particularly appealing has been a puzzle. We’ve now identified nerve cells in the gut rather than taste cells in the mouth are a key driver. We found that distinct gut-brain pathways are recruited by fats and sugars, explaining why that donut can be so irresistible.” 

Vagus nerve system 

The study highlights the role of the vagus nerve in transmitting nutritional information from the gut to the brain. This neural communication goes beyond the sensory experience of taste, originating instead in the gut, thereby affecting our eating behavior on a more primal level.

Using cutting-edge technology, the research team was able to directly manipulate neurons in the vagus nerve system of mice. 

By stimulating these neurons with light, the experts observed a subsequent dopamine release in the brain’s reward center. This approach allowed the team to isolate and identify the separate pathways for fat and sugar cravings.

Challenges of dieting

“It’s like a one-two punch to the brain’s reward system,” said Dr. de Lartigue. “Even if the total calories consumed in sugar and fats stays the same, combining fats and sugars leads to significantly more dopamine release and, ultimately, overeating in the mice.”

This finding suggests that human brains may be naturally inclined to seek out foods high in both fats and sugars, making conscious efforts to resist these foods more difficult than previously understood.

Study implications 

The implications of this research extend far beyond academic interest, opening new avenues for anti-obesity strategies. By targeting and regulating these newly discovered gut-brain reward circuits, there is potential for creating more effective interventions to curb unhealthy eating habits.

“The communication between our gut and brain happens below the level of consciousness,” said Dr. de Lartigue. “We may be craving these types of food without even realizing it.”

Exciting possibilities 

The team predicts that this line of research offers hope for future development of anti-obesity treatments. 

“Understanding the wiring diagram of our innate motivation to consume fats and sugars is the first step towards rewiring it,” said Dr. de Lartigue. “This research unlocks exciting possibilities for personalized interventions that could help people make healthier choices, even when faced with tempting treats.”

The study is published in the journal Cell Metabolism

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