Do obesity and stress affect appetite? Research suggests that the answer may lie in the brain

In a series of experiments using functional magnetic resonance imaging (fMRI) to measure brain activity in brain networks, researchers at the Johns Hopkins School of Medicine looked at how stress increases appetite in obese and emaciated adults
.
The researchers found that stress affects the brain's response to food, and that both lean and obese adults respond to food in areas
of the brain related to reward and cognitive control.

The results of the study were published Sept.
28 in
PLOS ONE.

For the study, researchers analyzed data from 29 adults (16 women and 13 men), 17 of whom were obese and 12 were thin
.
Participants completed two functional magnetic resonance imaging scans, one of which was after
a social and physiological stress test.

During both scans, participants were tested for food word reactivity
.
The test involves looking at people's brain responses to food vocabulary, such as menu items
on a blackboard.
To maximize the appetite response in the brain, the researchers asked participants to imagine what each food would look like, smell and taste, and what it felt the
moment they ate it.
They were also asked how much they wanted to eat each food and whether they felt they shouldn't eat it, to see how they made decisions related to each food
.

Lead researcher Dr.
Susan Carnell, associate professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine, said: "Experiments have shown that the brain responses of obese adults and lean people are somewhat different, and obese adults have less activation of cognitive control areas of food vocabulary, especially for high-calorie foods, such as grilled cheese
.
"

The study also showed that stress affects the brain's response
to food.
For example, after a stress test, obese people showed greater activation
in the prefrontal cortex of the eye socket (the reward area of the brain).
"We also found a link between
subjective stress experiences and brain responses in both groups.
For example, lean people who reported greater stress after the test had a lower degree of activation in the dorsolateral prefrontal cortex, a key brain region for cognitive control," Cannell said
.

Susan Carnell, Leora Benson, Afroditi Papantoni, Liuyi Chen, Yuankai Huo, Zhishun Wang, Bradley S.
Peterson, Allan Geliebter.
Obesity and acute stress modulate appetite and neural responses in food word reactivity task.
PLOS ONE, 2022; 17 (9): e0271915 DOI: 10.
1371/journal.
pone.
0271915