‘It just piles on’: Environmental stressors, gut-brain dysfunction drive eating behaviors

Key takeaways:

• Avoidant/restrictive food intake disorder is common among individuals with disorders of gut-brain interaction.
• Social determinants of health also impact the brain-gut-microbiome system.

Recent research has highlighted the effects of disorders of gut-brain interaction and environmental stressors — including social determinants of health — on two distinct eating behaviors.

Studies published in Gastroenterology and Clinical Gastroenterology & Hepatology characterized the interactions between stress, the gut microbiome and eating patterns, and demonstrated how these interactions drive both excessive eating and restrictive food intake.

“On a positive note, one thing we did notice is that social support and a sense of community and common humanity seems to buffer people against this intersection between stress and the microbiome,” study author Laurie Keefer, PhD, a clinical health psychologist and professor of medicine, psychiatry and biomedical sciences at Icahn School of Medicine at Mount Sinai, told Healio. “Isolation and loneliness represent a growing epidemic, and we’re seeing the impacts on health. Obesity is a perfect example of that.”

‘A downward spiral’

Disruptions to gut-brain communication can manifest as cravings for calorie-dense foods, or conversely, as restrictive eating. Recent research has focused on the overlap between disorders of gut-brain interaction (DGBI) and restrictive eating habits unrelated to body image.

To further assess this association, Imran Aziz, MD, MBChB, MRCP, and colleagues conducted a population-based online survey of 4,002 adults (median age, 46; 50% women) in the United Kingdom and United States. The survey included the Rome IV diagnostic questionnaire for DGBI, as well as the Nine-Item Avoidant Restrictive Food Intake Disorder (ARFID) Screen. The researchers also collected data on demographics, BMI, non-gastrointestinal somatic symptoms and quality of life, among other factors.

Aziz noted ARFID is distinct from more widely known eating disorders such as anorexia and bulimia.

“ARFID is an eating disorder where people severely limit what or how much they eat, leading to weight loss, nutritional problems or difficulty functioning in daily life,” Aziz, senior clinical lecturer in gastroenterology at University of Sheffield School of Medicine and Population Health, told Healio. “Unlike anorexia or bulimia, it’s not about body image — instead, people might have little interest in food, be extremely picky about textures or tastes, or fear that eating will cause choking or stomach pain.”

Results of the survey showed nearly half (42.6%) of participants had symptoms associated with at least one DGBI, and 34.6% of those with DGBI (34.6%) had positive screens for ARFID compared with just 19.4% without DGBI (adjusted OR = 1.67; 95% CI, 1.43-1.94). The most common symptoms in positive screens were lack of interest in eating (21.5%), sensory-based avoidance (18.1%) and fear of aversive consequences (9.9%).

“The relationship is complex and appears to work both ways,” Aziz said. “Digestive symptoms like pain, vomiting and unpredictable bowel movements can make people afraid to eat certain foods or eat at all. At the same time, not eating enough variety or quantity can make digestive problems worse and create more anxiety around meals, forming a harmful cycle.”

Participants with DGBI and ARFID also were more likely to be underweight compared with those with DGBI alone (7.9% vs. 1.5%), and they exhibited more non-GI somatic symptoms, had poorer mental and physical quality of life, and higher health care utilization.

“The restrictive eating worsens nutrition, while digestive symptoms make people avoid food even more, creating a downward spiral,” Aziz said.

Aziz encouraged clinicians to use simple screening tools and have discussions to identify ARFID in patients with DGBI, and to provide these patients access to multidisciplinary care that includes dietitians and mental health providers.

He also urged clinicians not to make assumptions about ARFID based on a patient’s BMI.

“Many people assume eating disorders only affect underweight individuals, but most patients in our study with both conditions were normal weight, overweight or obese,” Aziz said. “Doctors can’t rely on appearance alone to spot these problems.”

‘We can’t just keep blaming the individual’

Gut-brain communication also influences the microbiome, and can be affected by social determinants of health, which include psychosocial and environmental factors such as economic stability, access to health care, social support, neighborhood disadvantage and discrimination.

Keefer and colleagues conducted a systematic review of current literature to better understand the role these factors play in the development, progression and management of obesity.

They found that stressful life circumstances can drive physiological changes in the gut microbial composition, hypothalamic-pituitary-adrenal axis signaling and the reward network.

“We know that in the gut, particular chemical messengers like serotonin are very much influenced by the presence of stress and can affect the way the gut and the brain communicate, causing symptoms,” Keefer said. “There’s also what we call ingestion-related decision-making: what we choose to eat, when we choose to eat it and how we feel when we eat a particular food. When we’re stressed, we crave different types of food.”

This cycle of disruption, cravings and reward can influence eating habits in a way that is not easily overcome by individual willpower, she added.

“Our study found that the neighborhood you live in, and whether you felt and experienced chronic poverty or discrimination — racism in particular — can create a risk profile above and beyond anything an individual can do,” Keefer said. “We have all these interventions — do some yoga, eat more vegetables — but it’s not just about the individual. It’s about the societal stressors that affect individuals.”

Stress also can cause individuals to sacrifice sleep, exercise and quality nutrition even in ideal circumstances, adding that unsafe environments worsen this association.

“One of the things we found was these effects are worse when people live in neighborhoods where it’s not safe to go for a walk due to fears of gun violence, drugs or robbery,” Keefer said. “There are all sorts of things we’re seeing in terms of people’s psychological coping, in addition to what’s already going on at the microbiome level.”She added that the interaction of “ingestion-based” behavior with the brain’s reward system can often be self-reinforcing.

“The more sugar you eat, the more sugar you want,” Keefer said. “Your mood is depressed, and the sugar makes you feel good temporarily. Therefore, you eat it again to manage your stress. It just piles on.”

Community-based activities that foster support, encouragement and collaboration should be a major component of interventions aimed at managing obesity in marginalized populations, she noted.

“The other big takeaway from this paper is that we can’t just keep blaming the individual,” Keefer said. “We need to stop saying their weight problem or their eating behavior is all because of what they’re doing. We can treat individuals, but we also need to make an institutional commitment to changing the obesogenic environment and the role stress plays in eating behavior, not just weight.”

For more information:

Imran Aziz, MD, MBChB, MRCP, can be reached at imran.aziz1@nhs.net.

Laurie Keefer, PhD, can be reached at laurie.keefer@mssm.edu.

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