Science has been looking for the connection between weight problems and our brain for a long time. New research points to a gene that could prompt people to overeat and gain weight. The latest findings indicate that obese people appear to have fewer dopamine receptors in their brains…giving them less ability to feel pleasure from eating and encouraging them to eat more to get the same pleasure.
The research used magnetic resonance imaging (MRI) of the pleasure centers of the brain in a group of 53 college students and 33 teenage girls, looking at the response to food. Subjects were given sips of a chocolate shake and then an unflavored solution. The participants were also tested for the presence of a genetic variant called Taq1A1, linked to fewer dopamine D2 receptors in the brain. The subjects’ body mass index was then followed for one year.
At the end of the follow-up, the researcher found that the subjects whose brains were less activated by the chocolate shake and who had the gene variant were also more likely to have gained weight during the year of follow-up. The increase was 3.6%. “This is the first imaging study to find less activation of dopamine receptors in [some] humans,” said study lead author Eric Stice, a scientist at the Oregon Research Institute in Portland.
Dopamine is a neurotransmitter that is released when you eat… bringing that feeling of pleasure. In our distant past, this “chemical pleasure” was a reward to the body for eating a life-sustaining food. The amount of dopamine released is related to the level of pleasure experienced, and it seems that some of us are genetically predisposed to not having the number of dopamine receptors we need.
Previous work has shown that obese people tend to have fewer D2 receptors than leaner people. This may explain why some can eat whatever they want and not gain… and others feel like they eat normally and still gain.
This latest work is the result of a collaboration between clinical psychologists from the Oregon Research Institute and the University of Texas, and sensory neuroscientists from the John B. Pierce Laboratory and Yale University School of Medicine. The research was funded by a Roadmap for Medical Research grant (R1MH64560A) from the National Institutes of Health.
“What’s new here is that for the first time they have identified the consequences of this (type) genetic polymorphism on how the brain works,” said Dr. Nora Volkow, who has worked to identify the role of the D2 gene (the missing one in in ORI subjects) in overeating. Now director of the National Institute on Drug Abuse, she has worked hard to establish the link between addictive behaviors and the human brain. She also makes the connection between a lack of dopamine receptors and other abusive behaviors, instances of people doing things like compulsive drinking and drug use, even when they know better.
And while you can’t change your brain genetics right now, there are things you can do to help yourself fight weight problems. Eating a healthy diet and consuming meals more slowly are important first steps. You’ll also want to make sure you’re active, doing two to three exercises per week, to help activate the dopamine pathway and reduce the urge to overeat.