A new study may provide context as to why it’s harder for some people to start eating healthier foods, especially after years of eating unhealthy ones.
In this day and age, there’s no escaping foods that are both high in calories and fat. After all, grocery store shelves and restaurant menus are often saturated with these types of options. Still, those who have access to nutritious foods may find it difficult at times to start eating them, and regularly. New research suggests, however, that this challenge may be attributable to the way in which the brain responds to certain foods. (Related: 21 Best Healthy Cooking Hacks of All Time)
The study, which was published in the journal Nature, explored how eating a high-fat diet affects the brain and ultimately, one’s desire to eat healthier foods. Researchers gave mice both a high-fat diet (HFD) and a standard diet (SD). Across the board, the mice stopped eating the SD after the HFD was offered. But, when the HFD was taken away, the mice strangely ate very little of the SD. As a result, the mice lost weight. Even mice that were in the fasting group barely touched the SD during feeding time.
However, the fasting mice would engorge when the HFD was provided, and even after 24 hours of an HFD splurge, the mice would be less inclined to return to the SD. This prompted the scientists to then record the activity of AgRP neurons, which is a group of neurons that control energy balance and become active when you feel hungry. Scientists also monitored midbrain dopamine neurons, which release dopamine—the neurotransmitter that makes you feel good.
What they found? After eating the HFD, the mice experienced a reduction in responses from both groups of neurons when exposed to the SD. So much so that the neurons only responded strongly when the HFD was offered. In other words, the mice found the standard diet to be less satiating and less rewarding than the food that was higher in calories. (Related: This Is Why You Can’t Stop Buying Your Favorite Junk Food)
Another interesting takeaway was that after the mice experienced HFD withdrawal— which was the scientists’ way of mimicking dieting—their AgRP neurons were so sensitive to HFD that they would start responding even when the mice were not hungry. Researchers propose this activity could explain why high-calorie foods seem so irresistible when we try and diet—our brain processes these foods as more rewarding and valuable, even when we’re not necessarily hungry.
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