Researchers looked at MRI brain scans of volunteers that were shown dozens of types of foods and asked to decide which they'd prefer to eat. There were significant differences in brain activity between those who had self-control in making food choices and those who did not.
Previous research found an area of the brain called the ventromedial prefrontal cortex, or vmPFC, comes to life during all value-based decisions.
The more vmPFC activity at the time of the decision, the more likely the person is to make that choice. If activity decreases, that person is more likely to reject it.
According to the study, those with no self-control seemed to only take the taste of the food into consideration.
"In the case of good self-controllers, however, another area of the brain, called the dorsolateral prefrontal cortex (DLPFC) becomes active and modulates the basic value signals so that the self-controllers can also incorporate health considerations into their decisions," said principal investigator Antonio Rangel.
The study found that the vmPFC is active during every decision and that the DLPFC is more active when a person is using self-control.
"This, ultimately, is one reason why self-controllers can make better choices," said Rangel.
The study is published in the May issue of Science.