Mechanisms that contribute to obesity also end up affecting the brain, research finds

In 25 years, half of the world's population will be overweight or obese if nothing is done. In Denmark, 42% of the adult population is currently overweight or obese.

In 1997, WHO recognized obesity as a chronic disease, partly because researchers found a range of underlying biological, psychological, socioeconomic, or genetic factors that can contribute to obesity.

Recent research shows that many of these mechanisms end up affecting the brain. Whether it's hormonal imbalance, pollutants, stress, inactivity, disrupted metabolism, or obesity-promoting genes: the final destination for the series of physiological reactions that these mechanisms set in motion is often the brain.

Specifically, the dopamine pathways in the brain can be negatively affected. They are also called reward circuits and are also activated in substance addicts, alcoholics, and gamblers, for example.

"In research, there is increasing attention to the role of neurobiology in obesity. We now know, for example, that many of the gene variants predisposing us to overweight, are active in the brain."

"Although we don't know a lot about many of them, it was shown that they can activate reward centers, so we feel satisfaction from eating, especially palatable food based on simple carbohydrates and fat—just as we get satisfaction from the same reward centers by taking substances, smoking, or drinking alcohol," explains Jan-Wilhelm Kornfeld, head of research and professor at the Center for Adipocyte Signaling, Department of Biochemistry and Molecular Biology.

Together with colleagues from University of Aarhus, University of Southern Denmark and Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, he is scientific co-organizer of a symposium on the neurobiology behind obesity, taking place in Copenhagen, May 30–31 2024.

His research focus is to understand how gene activity is dysregulated in obesity. This includes studying fat cells from obese mice and humans. Together with physicians, chemists, and experts in gene therapy, he is also working to develop new treatment methods that may, in the future, correct the dysregulated gene activity in the fat cells of obese individuals.

Whether the growing insight into the neurobiology behind obesity insight should impact the way we treat obesity, and whether obesity should be considered a comorbidity of an addiction disease, he does not wish to comment on, as he is not a physician.

Secondly, it should also be noted that this medication does not cure the underlying problems that lead to obesity. It does not provide a solution but rather a symptom treatment, and not everyone has access or can afford it. The medication is expensive, and it will likely be so for the next five to 10 years. Additionally, manufacturers cannot keep up with demand.

He points out that the solution does not solely lie with the individual affected by obesity but also with society. One reason is that society can implement initiatives to make fattening foods and drinks less accessible. For example, countries like the United Kingdom and Mexico have introduced taxes on sugary drinks, leading to a significant decline in sales and consumption. Examples: Two years after Mexico introduced their taxes, sales had decreased by 9.7%. Six years after the UK's implementation, the number of obese girls in socially deprived areas had dropped by 9%.

Sugary drinks, in particular, are one of the food and beverage items that most effectively activate the brain's reward centers, causing a constant craving to consume them for a sense of reward.

Another necessary effort is for society—all of us—to take responsibility for destigmatizing obesity.

There is something about seeing a fat person eat that triggers us and makes us think that obese people have no willpower. Much more than when we see someone smoke or drink alcohol. We shame people who become obese from an unhealthy lifestyle—but we don't shame people, for example, who get liver cancer from heavy drinking.

Perhaps because alcoholism is not instantly visible, whereas obesity is. We don't have the same compassion for someone affected by obesity as for a liver cancer patient. Obesity is a disease associated with shame. But it is no shame to suffer from a disease, and we need to destigmatize it, says Jan-Wilhelm Kornfeld

Provided by University of Southern Denmark