In a recent study on mice, it was seen that a brain circuit specifically contributes to the tendency of overeating unhealthy foods. Many people can resonate with scenarios where they consume an entire bag of chips despite not being hungry. It’s not only humans who have this affinity for high-calorie foods, but also other mammals. In evolutionary context, it makes sense for animals to consume as much nutrient-rich food when they discover it, as starvation is a constant threat in the wild. Nowadays, we have easy access to energy-dense foods with high sugar and fat content, a condition evolution has not prepared us for.
Ordinarily, animals eat until their hunger is satisfied and energy levels are restored through homeostatic feeding. There is, however, another type of feeding known as hedonic feeding where an animal consumes more than necessary if the food is especially nutrient-rich and appetizing. Most of the time, our advanced brains can control these urges, but not always. Studies by Professor Thomas Kash, Ph.D. point to the fact that our constant exposure to high-caloric food aligned with our primitive habit to consume as much nutrient-dense food as possible could lead to conditions like obesity.
Prior research focused on controlling homeostatic feeding as a way to decrease obesity, but without much success. More recently, scientists have started to consider hedonic feeding as a factor. Findings suggest that nociceptin, a neuronal peptide, may have some role in hedonic feeding. This information opens up possibilities for development of “anti-binging drugs”, although the process is still far from completion.
Nevertheless, Professor Kash and his team have made significant progress by identifying a neural circuit in mice that is closely linked to hedonic eating. Remarkably, they used mice that produce a fluorescently marked nociceptin so they could easily identify involvements of nociceptin circuits. The identified circuit lights up when the mice consume energy-dense foods and seems to have connections to parts of the brain that control feeding. It turns out that this circuit originates in the central nucleus of the amygdala, responsible for emotional responses in animals.
While the researchers indeed made an intriguing discovery, this is just the beginning. Much more research is needed to fully understand this new mechanism and how it impacts the broader picture. Also, it’s important to take into account the limitations of using mice as a model for studying binge eating. While rodents have provided useful information about human feeding control, binge eating is quite a different case due to the psychological aspects involved.
Overall, there is more to learn about the world of brain circuit-induced overeating, and the research continues.