Altered Brain Activity In Obese Women: Study Shows That Activity In The Reward Centers Of Obese Women React Differently To Food

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Food Cues And Your Brain On Obesity: New Study Shows That Obese Women’s Brains Continue To React To Food Signals Even When They Are Full

As we learn more and more about the brain, the more we learn about how the entirety of the human body is interconnected. From evidence that gut bacteria can control our cravings for certain foods to a recent study that seems to indicate that obese women’s brains continue to react to food stimuli even after they are full, there has never before been such a time when we might understand how the organism works.

The study was published in the journal Obesity, looked at the brain activity of 15 severely obese women–those with a body mass index of more than 35–and 15 lean women, defined as having a BMI under 25.


By studying MRI images of the women’s brains before and after eating, the University of Texas Southwestern researchers found that the obese women continued to respond to food cues even after they had eaten and were no longer hungry.

As expected, both groups showed significantly increased activity in the neo- and limbic cortices and midbrain when they were hungry. But after they had eaten, that brain activity fell among the lean participants, while continuing in the obese women–even after they had reported that they were no longer hungry, reacting to photos of food the same way.

While the brain’s reaction to the pictures of food dropped 15 percent for the lean women following a meal, the severely obese women showed only a 4 percent decline. Furthermore, activity in regions in the prefrontal cortex and posterior cingulate cortex significantly changed in the lean group after they had eaten, but not in the obese group. The obese study participants continued to show activity in the midbrain, one of the body’s most potent reward centers.

“Before or after the meal, they’re just as excited about eating,” said study lead author Dr. Nancy Puzziferri, an assistant professor of surgery at UT Southwestern. “It seems they have an instinctive drive to keep eating.”

Study participants were required to fast for nine hours prior to testing, at which time they were asked to rate their level of hunger or fullness. They were then given a brain scan as they viewed pictures of food.

They were then asked again to rate their level of hunger. During the next hour, the women were fed a meal of lean beef or chicken, potatoes or rice, green beans, canned peaches, and iced tea or water. Following the meal, the study participants were taken through another series of hunger/fullness ratings and MRI scans and shown pictures of food.

The obese women continued to show brain activation consistent with hunger despite reporting that they were equally as full as their lean counterparts. The implications for helping obese people bring down their weight are hard to overstate.

“These findings may explain why some people with severe obesity report an underlying drive to eat continually despite not feeling hungry,” said Dr. Puzziferri.

Indeed, pointing out a glitch in the brain like this could be the first step in elimination obesity altogether.

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