“Think of executive control as the brakes,” said psychologist Arpana Gupta, who is the co-director of the Goodman-Luskin Microbiome Center at the University of California at Los Angeles and the study’s lead author. If you have faulty brakes, it becomes hard to avoid the food you are craving, “but if your brakes are working really well, you tap them a little bit and it’s going to stop you from going for that craving,” she said.
The study by Gupta and other researchers at UCLA was published Friday in JAMA Network Open.
These findings are a step toward understanding the physiological connection between loneliness and unhealthy eating, which could inspire immediate changes in behavior and future targets for obesity treatments.
A similarly designed study in men could help tease apart sex-specific differences in brain activity related to loneliness and eating habits, because men and women have different brain patterns when it comes to obesity, Gupta said. And to understand the cause and effect — vs. correlation — between loneliness and eating habits, a follow-up longitudinal study would be needed, which would require collecting data from participants across many time points, she said.
Lonely brain changes are strongest for sweet foods
The researchers collected demographic and body composition data, including the body mass index number, from 93 healthy premenopausal women in Los Angeles, ages 18 to 50, with an average age of about 25.
The women completed questionnaires about their mental health, eating behaviors and their perceived social isolation, also known as loneliness. Perceived social isolation was assessed using the established Perceived Isolation Scale, which measures the frequency of support from friends, family and partners.
The brains of the participants were then scanned using functional magnetic resonance imaging (MRI), which measures changes in blood flow throughout the brain as a proxy for activity.
Since other neurological studies had shown an association between loneliness and changes in different brain networks involved in reasoning, intrinsic awareness, visual attention and reward, the researchers examined those same networks in the context of food cues.
While in the MRI scanner, the women were shown images of different categories of foods. One set was of high-calorie sweet foods such as chocolate cake and ice cream. Another was of high-calorie savory foods such as french fries and burgers. There also were two low-calorie food categories — one savory, one sweet — which included salads and fruits, respectively.
Participants were shown nonfood pixelated images as a control for comparison.
The functional MRI data showed that participants with higher perceived social isolation had increased brain activity to food cues in the inferior parietal lobule, a brain structure associated with rumination, and the occipital cortex, which converts what your eyes detect into information.
These participants also showed reduced activity in their dorsolateral prefrontal cortex, a part of the brain important for reasoning and inhibition that is within the executive control network.
Changes in brain activity were strongest when participants with higher perceived social isolation saw sweet, high-calorie foods such a chocolate cake. Sweet foods are known to stimulate our brain’s reward center, and one theory is that they could serve as a source of pleasure during times of loneliness, helping “reduce social pain and discomfort that’s associated with being alone or being isolated,” Gupta said.
Separately, from the body composition and questionnaire data, the researchers found that participants with higher perceived social isolation had higher fat mass percentage and self-reported lower diet quality and poor mental health, which included decreased psychological resilience — the ability to adapt to challenging circumstances.
Loneliness and eating behavior
“We talk about things like the fact that you might eat for emotional reasons, you might crave certain types of foods,” said Katherine Hanna, a lecturer in nutrition and dietetics at Queensland University of Technology who recently published a large research review on the association between loneliness or social isolation and food and eating behavior. But, “what this study does is it actually looks into how the brain reacts,” starting to fill in the pathway linking loneliness and eating, she said.
“Part of the problem has been this tendency to oversimplify the reasons we eat what we eat, which leads to things like judgmental attitudes or ‘Why don’t you just eat better?’” said Hanna, who was not involved in the recent study. “And of course, changing our eating is so much more complicated than just knowing or having enough willpower.”
Eating behavior and obesity contribute to many chronic diseases, and understanding how loneliness is connected to food-related behaviors — as this study tries to do — could help explain how it also contributes to chronic diseases and early mortality, said psychologist Louise Hawkley, a senior fellow at the National Opinion Research Center at the University of Chicago.
However, said Hawkley, who was not involved in the study, “a better assessment of eating behaviors will be needed, not just self-reported behaviors.”
Ways to counter loneliness
There are ways to connect with people, which would benefit our eating behavior and our overall physical and mental health, the experts said.
Hanna suggested finding ways to eat and even prepare food with other people. “It’s not just nourishing our bodies but also nourishing our social connections,” she said.
For instance, when at work, take some time to eat in communal eating places rather than at the desk, Hanna suggested. Sign up for a cooking class or volunteer for a food-related organization such as a community garden or a meal preparation and delivery service.
“Loneliness is more highly related to poor quality relationships” that cause stress or conflict “than to a deficit in relationships,” said Hawkley, much of whose research is focused on loneliness and its associations with health during aging. “Maybe the first decision is whether to keep these relationships or let them go.”
“On the other hand, if you perceive signs of rejection or exclusion that hinder you from even trying to connect with others, you may benefit from a professional’s help,” she said.
Hawkley also suggested finding an interest group or volunteer organization that aligns with what you care about. “Instead of looking for signs of rejection or exclusion, look for signs of acceptance, hints of connection, people who may be as hungry for a connection as you are,” she said.
Based on the functional MRI data, Gupta said, finding activities that help you avoid ruminating on cravings and instead strengthen your executive control could make a difference. She suggested meditation and other stress reduction exercises such as journaling. And, she said, when your brain’s reward center is crying out for a sweet craving, try grabbing a handful of berries instead of that second slice of cake.
If you’re experiencing loneliness but are also overwhelmed by what to do first, start simple — maybe call a friend for a quick chat or send a text message. You don’t have to go out and about and be some “social butterfly,” Gupta said. “If we empower people to do these little things, it adds up to make a difference when lonely.”
Do you have a question about human behavior or neuroscience? Email BrainMatters@washpost.com and we may answer it in a future column.
