People are obese, because they can’t stop eating, because they really enjoy eating — or do we have it all backwards?
According to a new study from Kyle Burger and Eric Stice at the Oregon Research Institute, those who overeat may actually get less pleasure from food. So they’re forced to consume larger quantities (and added calories) to achieve an equivalent reward.
The researchers began by asking 151 adolescents about eating habits and food cravings. Then, they stuck the teens in a brain scanner while showing them a picture of a milkshake followed by a few sips of the real thing. They were particularly interested in looking at the response of the dopamine reward pathway in the brain, a cortical network responsible for generating the pleasurable emotions triggered by pleasurable things.
By comparing the response of the reward pathway to the eating habits of the adolescents, the scientists were able to show that those who ate the most ice cream showed the least activation in their reward areas when consuming the milkshake. This suggests that they were eating more in desperate compensation, trying to make up for their indifferent dopamine neurons. People crave pleasure, and they don’t stop until they get their fill, even if means consuming the entire pint of Häagen-Dazs.
This research builds on previous work by Dr. Stice documenting the dangerous feedback loop of overeating. Although people struggling with obesity tend to have less-responsive reward pathways—they even have fewer dopamine receptors—overeating makes the problem worse, further reducing the pleasure from each bite. Like an alcoholic who needs to consume ever-larger quantities of liquor to achieve the same level of intoxication, individuals with “hypofunctioning reward circuits” are forced to eat bigger portions in search of the same level of satisfaction. It’s an addiction with diminishing returns.
It’s an addiction with diminishing returns.