"Discovery: Eating Sugary and Fatty Foods Activates Gut-Brain Link."

 

Craving both sugar and fat simultaneously presents a formidable challenge to dieting, according to recent research conducted by a team from the Monell Chemical Senses Center. Their investigation into the brain's reward systems has unveiled new brain-gut circuits for sugar and fat, triggering cravings for unhealthy foods without our awareness.

The researchers propose that the combined cravings for sugar and fat create a compelling desire to overeat. This discovery sheds light on the irresistible allure of fats and sugars, raising hopes for more effective dieting strategies.

While we comprehend food's powerful influence on our choices, the precise brain circuitry behind it has remained a mystery. The study reveals distinct fat and sugar-craving pathways in the brain, emphasizing the concerning reality that the combination of these pathways excessively triggers our desire to eat more than usual.

Dr. Guillaume de Lartigue, a lead author from the Monell Chemical Senses Center, describes it as a "one-two punch to the brain's reward system." Even if the total calories consumed in sugar and fats remain the same, combining them leads to significantly more dopamine release and, ultimately, overeating in the mice.

The researchers stress that although food is a powerful reinforcer, the specific appeal of fats and sugars 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," Dr. de Lartigue adds.

The research provides insights into "motivated" eating behavior, suggesting a subconscious internal desire for a diet high in both fats and sugar can undermine efforts to maintain a healthy weight.

Manipulating fat or sugar neurons in the vagus nerve systems of mice, the researchers demonstrated that both types cause dopamine release in the brain's reward centers. They identified two dedicated vagus nerve pathways: one for fats and another for sugars, conveying information about food consumption to the brain and stimulating cravings.

By stimulating gut vagal nerves with light, the team induced mice to actively seek food, revealing that sugar and fat are sensed by separate neurons of the vagus nerve and engage distinct reward circuits to control nutrient-specific reinforcement. Activating both the fat and sugar circuits simultaneously created a strong craving synergy, leading the mice to overeat. This finding illuminates why dieting is often difficult: our brains are subtly wired to seek out high-fat, high-sugar combinations.

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

The team hopes their research can be used in the future to develop anti-obesity strategies and treatments, making dieting easier by altering gut-brain reward circuits to reduce unhealthy eating habits.

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