Obesity may be caused or maintained by enhanced neurobehavioral responsiveness to food-related cues in the environment. Consistent with this hypothesis, a number of neuroimaging studies have demonstrated increased activation among overweight individuals in response to food pictures within regions subserving reward, emotion, memory, and sensorimotor functioning, and reduced activation in regions subserving attention and self-regulation, although recent large studies and meta-analyses have failed to find robust weight group differences, highlighting the likely role of individual and situational variation in influencing food cue responses.
Understanding the neural basis of stress-related appetite could potentially aid the development of targeted neurobehavioral interventions to reduce excessive eating triggered by stress. A stress-induced food reward model has posited that repeated stimulation of brain reward pathways through stress and food intake leads to neurobiological adaptations that drive stress-induced overeating.
Medicine researchers looked at how stress might increase appetite in obese and lean adults
For the study, the researchers analyzed data from 29 adults (16 women and 13 men), 17 of whom had obesity and 12 of whom were lean. Participants completed two fMRI scans, one following a combined social and physiological stress test.
Participants were given a food word reactivity test during both scans. This test involved looking at how people’s brains reacted to food words, such as menu items on a chalkboard. To maximize the appetitive response in the brain, the researchers asked participants 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 wanted each food, and if they felt they should not eat that food, to see how they approached decision-making related to each food.
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.
The study also showed that stress impacts brain responses to food. For example, obese individuals showed greater activation of the orbitofrontal cortex, a brain reward region, after the stress test. They 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.
Susan Carnell, Leora Benson, Afroditi Papantoni, Liuyi Chen, Yuankai Huo, Zhishun Wang, Bradley S. Peterson, Allan Geliebter, (September 28, 2022). Obesity and acute stress modulate appetite and neural responses in food word reactivity task. PLOS ONE. Retrieved from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0271915