Overconsumption of high-fat foods dampens the dopamine-induced reward sensation, leading to compensatory consumption of even more high-fat foods.
Scientists who study digestive disorders have known for some time that there is a connection between our guts and our brains. Your gastrointestinal track is actually a nervous system, just like your brain. There is a nerve that connects your brain to your gut, and if it fails, your digestive system will work anyway; it functions all on its own.
Researchers have found that people with digestive conditions like Crohn’s disease, gastroesophageal reflux disease, irritable bowel syndrome, and others are at risk for certain mental health problems including depression and anxiety. It should come as no surprise then that there is a brain connection when it comes to overeating. New research is showing that obesity could be considered an addiction very similar to drug addiction because of what happens in our brains when we eat.
Drugs, Food and the Brain
There are many motivations for using and abusing drugs, but there is one biological reason: it feels good. When a person uses a drug to get a high, the drug goes to the brain and other parts of the nervous system and activates certain receptors. In the brain, this activation causes a molecule called dopamine to be released in large quantities. Dopamine makes you feel good.
It turns out that food can also trigger a release of dopamine. This was probably important for evolution. When people had to work hard for food, long before it was readily available, the brain chemical reward system would have motivated the search for something to eat. Especially rewarding in the brain are calorie-dense foods.
When the reward system in your brain with respect to food malfunctions, you might end up overeating. If you have a normal dopamine reward system, you eat a satisfying meal, feel full, feel good, and stop eating. If your reward system does not respond fully to the food you eat, you may need to eat more just to get that pleasurable feeling. Researchers think this might be happening in the brains of people who overeat, and who end up obese as a result.
Something similar happens in the brains of drug addicts. Drugs initially cause a flood of dopamine in the brain of the user, which produces a high. Over time, though, and with more use of the drug, the reward pathway gets messed up and the user needs more and more of the drug to get any pleasurable feelings.
A recent study, conducted at Yale University and published in Science, found that mice consuming high- fat foods had deficient dopamine responses. The foods were injected directly into the mice’s guts so that the smell and taste would not affect the dopamine release. It seems that calories coming from mostly fat alter the reward pathway, which can lead to overeating. This suggests that mice — and humans — may overeat in an attempt to restore dopamine release to normal levels.
The Yale researchers believe their work is very promising. Understanding the underlying brain signaling pathways involved in overeating and obesity could help people overcome food addictions and get back to a healthy weight. To continue to uncover the mysteries of the brain-gut connection, the researchers hope to extend their work to human participants. They would like to discover if the molecule that helped mice get more pleasure from their food could help people too. They also plan to investigate bariatric surgery to find out if there is a link between the success of weight-loss surgery and the pleasure pathway in the brains of patients.
Treating obesity and overeating as an addiction similar to the abuse of drugs or alcohol holds great promise for helping many people. Obesity is a major problem in the U.S. and has even been listed as a disease by the CDC, in an attempt to force people to take weight more seriously. By labeling it as an addiction, continued research should be able to lead to the development of more successful treatments that get people to eat right and maintain healthy weights.