Can your appetite be influenced by stress?

Researchers at the Johns Hopkins University School of Medicine conducted an experiment on 29 participants to measure their brain activity and analyze how stress impacted their appetite. The participants were divided into two groups—one group of 17 obese adults and another of 12 lean adults. 

The results published in PLOS ONE journal revealed, in both groups, stress affected their brain’s responses to food, especially in areas of the brain associated with reward and cognitive control.

The participants first underwent an fMRI (functional magnetic resonance imaging) scan. Then, they completed a social and physiological stress test after which they underwent another fMRI scan. 

During both scans, participants took a food word reactivity test to understand how their brains reacted to food words written on a chalkboard. To increase their appetite responses in the brain, researchers asked them to imagine the smell, appearance, taste, and experience of eating each food item. To identify their approach toward food-related decision-making, they were also asked to think about how much they wanted each food item and if they felt they should avoid eating it.

In our brains, the orbitofrontal cortex is responsible for integrating inputs from all 5 senses and processing rewards and punishment. The dorsolateral prefrontal cortex takes care of reasoning and impulse-control. 

The stress tests revealed that in obese adults, the orbitofrontal cortex was highly activated, which means stress created an urge to consume food. In lean adults with higher stress, the dorsolateral prefrontal cortex had low activation. This means, stress made them incapable of making a logical decision and tempted them to reach for food.

The results thereby concluded that neural responses to food cues are influenced by stress, which could also impact the level of food consumption.