Discriminatory experiences are psychological stressors known to stimulate the desire to eat and motivation to seek unhealthy foods through increased appetite and food cravings, leading to stress-related weight gain and obesity as research has shown. However, a biological explanation for how discriminatory experiences lead to obesity is unclear.
To address this gap, researchers investigated the impact of discriminatory experiences on the brain-gut-microbiome system to help uncover how people respond to food cues—the mental associations individuals make with food that determine food-related responses, which can be triggered by hearing, seeing, smelling, or perceiving of food or reliving food-related memories. In the brain-gut-microbiome system, the health of the gut and the diversity of its microorganisms influence brain function and behavior, and stress can alter this connectivity.
The study participants included 107 people (87 women and 20 men, 18 years to 54 years) in Los Angeles who agreed to fast for 6 hours before their magnetic resonance imaging (MRI) brain scans. Participants were categorized into two groups:
- High self-reported discrimination exposure group.
- Low self-reported discrimination exposure group.
There were no significant differences in sex, age, body mass index, education, marital status, income, or diet between the two groups. However, socioeconomic status was significantly lower among individuals with high discrimination exposure.
Using MRI, researchers compared participants’ brain activity while they viewed non-food images and pictures of healthy (i.e., low-calorie savory and sweet foods) and unhealthy foods (i.e., high-calorie savory and sweet foods) and rated their willingness to eat the foods they viewed. Stool samples were collected and analyzed.
Comparing the results for both groups while they viewed images of unhealthy foods, the MRI images showed more reactivity in the regions of the brain involved in reward for eating pleasurable food, motivation for unhealthy foods, and self-regulation in participants reporting high levels of discriminatory experiences than in participants reporting lower discrimination exposure. Participants in the high discrimination group also had higher ratings of willingness to eat unhealthy foods. Analyzed stool samples showed greater discrimination exposure associated with an altered gut microbiome system that is typical in stress, inflammation, and obesity.
The researchers concluded that experiences of discrimination as a stressor can heighten food-cue response and alter the brain-gut-microbiome system to promote unhealthy eating behaviors, leading to inflammation of the body and risk for obesity. They suggest that treatments that normalize these alterations, such as food supplements or diets with anti-inflammatory benefits, may help individuals who experience discrimination-related stress.
Page updated July 19, 2024 | published March 29, 2024