Vagus nerve signals influence food intake more in higher socio-economic groups

A new study published in Food Quality and Preference suggests that the way our bodies signal hunger and fullness might be shaped by our socio-economic background. Researchers found that signals from the vagus nerve—an important biological pathway connecting the gut and brain—were more strongly linked to food consumption in individuals from higher socio-economic backgrounds. Individuals from lower socio-economic groups, on the other hand, appeared less influenced by these internal cues when deciding how much to eat.

The vagus nerve plays a key role in transmitting information between the gut and brain. It helps regulate digestion, appetite, and emotional responses to stress. A common way to assess vagal activity is by measuring heart rate variability, or HRV, which reflects how flexibly the body adjusts its heart rate. Higher HRV tends to be associated with better self-regulation and emotional control, including the ability to resist impulses like overeating. Researchers have long theorized that physiological self-regulation, like that provided by vagal tone, plays an important role in eating behavior.

The current study was designed to test how vagal tone might interact with socio-economic status to shape eating habits. To do this, the researchers focused on a very specific behavior: chocolate consumption. Chocolate is a high-fat, high-sugar food known to trigger cravings and emotional eating, making it a good model for studying self-regulation. The study included 96 university students in the United Kingdom who came from a wide range of socio-economic backgrounds.

To assess participants’ socio-economic status, the researchers used two approaches. First, they asked students to report their perceived status compared to other students. Second, they recorded the highest level of education achieved by each participant’s parent or guardian. This two-pronged approach allowed them to capture both subjective and objective aspects of socio-economic background.

Once in the lab, participants were fitted with sensors to record their heart activity. The researchers collected HRV data during a rest period and also during two tasks designed to cause mild stress. One task involved mentally subtracting sevens from a large number under time pressure, while the other required participants to give a short speech about what it would be like to die from cancer.

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After these tasks, participants entered a relaxation phase and then took part in a “taste test” that was, in fact, the key measure of eating behavior. They were left alone with a plate of 70 milk chocolate droplets and told they could eat as many as they liked while evaluating the taste.

The main question was whether participants’ vagal tone, as measured through HRV, would predict how much chocolate they ate—and whether this relationship would be different depending on their socio-economic status. The researchers tested three possible patterns.

First was the “blunting” hypothesis: that people from lower socio-economic backgrounds might have lower baseline HRV, leading to less effective self-regulation and more eating. Second was the “hyperreactivity” hypothesis: that stress would trigger stronger physiological responses (such as vagal withdrawal) in low-SES individuals, leading to more eating. Third was the “dissociation” hypothesis: that internal physiological signals (like vagal tone) might only guide behavior among higher-SES individuals, while lower-SES individuals would show weaker alignment between those signals and their eating.

The results did not support the first two ideas. There was no significant relationship between socio-economic status and baseline vagal tone, and vagal tone alone did not predict how much chocolate participants consumed. Similarly, there was little evidence that stress responses (vagal withdrawal) were higher in low-SES individuals or that such responses predicted more eating.

However, the third hypothesis—the dissociation hypothesis—was supported. Among participants from higher socio-economic backgrounds, higher baseline vagal tone was linked to eating fewer chocolates. This suggests that in these individuals, the body’s internal regulation systems were more closely aligned with their eating behavior. In contrast, among those from lower socio-economic backgrounds, there was no significant link between vagal tone and chocolate consumption. Even though their bodies may have sent signals of satiety or restraint, those signals did not appear to influence how much they ate.

These patterns held even after accounting for factors like hunger, body mass index, how much participants liked the chocolate, and whether they were actively trying to restrict their food intake. The researchers also repeated the analyses using slightly different methods and found consistent results.

This dissociation between physiological signals and behavior may help explain why people from lower socio-economic backgrounds are more vulnerable to overconsumption in environments filled with processed, high-calorie foods. If internal signals are less likely to influence behavior, external cues like portion size, advertising, and emotional triggers may play a larger role. This could lead to patterns of eating that are less in tune with actual energy needs, contributing over time to health problems such as obesity or diabetes.

One explanation for this dissociation may be differences in early life stress. People who grow up in unpredictable or unsafe environments—conditions more common in low-income households—may develop habits that favor immediate rewards over internal regulation. Other research has shown that early life adversity can reduce what scientists call “interoceptive sensitivity,” or the ability to detect and respond to internal bodily signals like hunger and fullness. Over time, this might impair the brain’s ability to use physiological signals to guide eating decisions.

“The findings suggest that while the vagus nerve plays a key role in transmitting signals between the gut and the brain, the extent to which these signals guide eating behaviour can vary with one’s socio-economic status,” the study’s lead author, Mario Weick of Durham University, explained. Our research indicates that internal signals may be more closely aligned with eating behaviour in individuals from higher socio-economic backgrounds. In contrast, those from lower socio-economic groups appear to show a weaker link between these physiological signals and their food consumption.”

The study has some limitations. It focused only on chocolate consumption and included a relatively young, university-based sample. Future research will need to determine whether these findings extend to other kinds of food, different types of stress, or more diverse populations. The researchers also acknowledge that their design does not prove causation—it cannot definitively say whether socio-economic status causes changes in vagal regulation or whether other variables are at play.

Co-author Professor Milica Vasiljevic emphasized that the study should not be interpreted as blaming individuals from lower socio-economic backgrounds. “Our study does not support the idea that individuals from lower socio-economic groups eat more or are inherently more impulsive,” she said. “Rather, it highlights that the internal regulation of eating – how our bodies naturally signal when to eat and when to stop – may function differently depending on our socio-economic backgrounds. This could have important implications for understanding broader health inequalities.”

Future studies might explore whether practices like mindfulness, yoga, or biofeedback can help boost vagal tone and interoceptive sensitivity, especially in disadvantaged groups. If so, such interventions could offer a promising way to support healthier eating habits from the inside out.

The study, “Socio-economic status modulates the link between vagal tone and chocolate consumption,” was authored by Mario Weick and Milica Vasiljevic.