HQ Team
October 20, 2022: Stress impacts the brain’s response to food in both obese and lean individuals, says a Johns Hopkins study
Researchers from the centre conducted a series of experiments using functional magnetic resonance imaging (fMRI) to measure brain activity and found that both lean and obese adults react to food cues in areas of the brain associated with reward and cognitive control.
For the study, the researchers analyzed data from 29 adults (16 women and 13 men), 17 of whom suffered from obesity and 12 were lean. Participants completed two fMRI scans following a combined social and physiological stress test.
Participants were asked to react to images and food-related words before each scan. To maximise the response, participants had to imagine how each food looked, smelled and tasted and how it would feel to eat it at that moment. They were also asked how much they were tempted to eat the food and what decision they made or wanted to make regarding the same impulse.
“The experiments showed that obese and lean adults differ somewhat in their brain responses, with obese adults showing less activation of cognitive control regions to food words, especially to high-calorie foods, like, for example, grilled cheese,” says lead researcher Susan Carnell, Ph.D., associate professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
Obese individuals showed greater activation of the orbitofrontal cortex, a brain reward region, after the stress test. “We also found evidence for links between the subjective stress experienced and brain responses in both groups. For example, lean individuals who reported higher stress following the test showed lower activation of the dorsolateral prefrontal cortex, a key brain area for cognitive control,” says Carnell.
“stress eating” is a phenomenon. Many other tests have shown that stress affects the choices we make in eating food. Stress unleashes hormones that push people toward overeating. Researchers have linked weight gain
Stress controls appetite
In the short term, stress can be an appetite suppressor. The nervous system sends messages to the adrenal glands atop the kidneys to pump out the hormone epinephrine, also known as adrenalin, which can temporarily put eating on hold.
The adrenal glands release another hormone called cortisol, and cortisol increases appetite and may also ramp up the motivation to eat. Continual stress leads to the hormone being in an “on” position, and cortisol may stay elevated.
A Finnish study that included over 5,000 men and women showed that obesity was associated with stress-related eating in women but not in men. Another 2007 British study found that people who responded to stress with high cortisol levels were more likely to succumb to snacking than low-cortisol responders.
The findings of the study were published in PLOS ONE.
