A recent study on the neurobiology of food addiction is getting a lot of attention. Maia Szalavitz has a very good summary of its findings.
The study used fMRI brain scans of subjects with and without food problems being shown sweets and bland, boring foods.
The scientists found that when viewing images of ice cream, the women who had three or more symptoms of food addiction — things like frequently worrying about overeating, eating to the point of feeling sick and difficulty functioning due to attempts to control overeating or overeating itself — showed more brain activity in regions involved with pleasure and craving than women who had one or no such symptoms.
These areas included the amygdala, anterior cingulate cortex and medial orbitofrontal cortex — the same regions that light up in drug addicts who are shown images of drug paraphernalia or drugs.
Similar to people suffering from substance abuse, the food-addicted participants also showed reduced activity in brain regions involved with self-control (the lateral orbitofrontal cortex), when they actually ate the ice cream.
In other words, women with symptoms of food addiction had higher expectations that a chocolate shake would be yummy and pleasurable when they anticipated eating it, and they were less able to stop eating it once they started.
Interestingly, however, unlike drug addicts, the participants with more signs of food addiction did not show a decrease in activity in pleasure-related regions of the brain when they actually ate the ice cream. People with drug addictions tend to derive less and less pleasure from drug use over time — they want drugs more but enjoy them less, creating compulsive behavior. But it’s possible that this tolerance may be seen only in serious addictions, not in people with just a few symptoms.
She also noted that there was not a relationship between weight and these neurobiological response. Maybe because of that tolerance factor?
UPDATE: 2 questions:
- If these neurobiological factors have a weak association with obesity, what factors are related to obesity?
- Are these neurobiologocal factors chronic? A lot of people can relate to having weak control at various times in their life. For these people, is this chronic or does it ebb and flow?