Cortisol reactivity and eating styles play a key role in the relationship between daily stress and snacking behavior, according to new research published in Psychoneuroendocrinology. The findings suggest that people’s physiological responses to stress can influence their eating choices and patterns.
“It’s well known that many people eat more unhealthy foods when they experience stress and this can be damaging for their health in the long run,” said study author Daryl O’Connor, a professor at the University of Leeds and head of the Laboratory for Stress and Health Research.
“However, less is known about the complex relationship between stress and eating in adolescents and young adults. Therefore, in this study we wanted to investigate the types of stressors that are associated with unhealthy snack intake and explore the role of the key stress hormone, cortisol, in understanding who might be most vulnerable to stress-induced eating.”
The study included a total of 123 participants, who were recruited from local schools and universities. Among them, 59 participants were adolescents (aged 16-18 years), and 64 participants were young adults.
The participants completed a modified version of the Trier Social Stress Test. Participants were tested in groups and were asked to prepare a speech to convince a panel of experts why they are the best candidate for a hypothetical job. They were also given a serial subtraction task. These tasks were designed to induce a subjective and neuroendocrine stress response.
Saliva samples were collected from the participants at four different time points before and after the stress task to measure cortisol levels. The samples were frozen to preserve stability, and cortisol levels were determined using an enzyme-linked immunosorbent assay kit.
The samples were used to assess cortisol reactivity, which refers to how the hormone responds to stress or challenging situations. Cortisol is released by the adrenal glands in response to stress, and it plays a role in regulating metabolism, immune function, and other processes.
Next, the participants completed a baseline questionnaire that included demographic information and eating styles measured using the Dutch Eating Behavior Questionnaire (DEBQ). The questionnaire was used to assess restrained, emotional, and external eating behaviors.
Participants were then asked to complete online daily diaries for 14 consecutive days after the test day. They recorded daily stressors they experienced and between-meal snacks they consumed. The researchers collected 1,196 individual diary entries.
The participants reported experiencing an average of 1.63 stressors per day, with work/academic stressors being the most common, followed by physical stressors. The researchers found that daily reported stress was positively associated with daily snacks, but not with fruit and vegetable intake.
“Daily stressors are associated with increased unhealthy eating in adolescents and young adults. Therefore, it’s important to be aware that small daily stressors, as well as larger stressors, can trigger high fat food consumption,” O’Connor told PsyPost.
Emotional and external eating styles both influenced the relationship between daily reported stress and total snack intake. Emotional eating intensified the impact of stress on snack consumption, with higher levels of emotional eating corresponding to a stronger relationship between stress and snacking. A similar pattern was observed for external eating style.
“Adolescents and young adults who are higher on eating style traits known as emotional eating (i.e., having a tendency to eat more when one is anxious and upset) and external eating (i.e., having a tendency to eat in response to external triggers such as smell and seeing visual cues) are more likely to eat unhealthy foods on days when they experience daily stressors,” O’Connor explained.
Interestingly, the researchers also found that stress was associated with increased snack intake among individuals with low and moderate levels of cortisol reactivity, but this association was not observed in individuals with high levels of cortisol reactivity.
Those with high levels of cortisol reactivity ate a similar number of snacks on both low and high stress days. This suggests that in people who have a strong stress response, any stressor, regardless of its severity, can influence their eating habits.
“Individual differences in the amount of cortisol release in response to stressors (in the laboratory) were associated with stress-induced eating,” O’Connor told PsyPost.
The researchers recommend exploring other aspects of hypothalamic-pituitary-adrenal (HPA) axis functioning, which is involved in the body’s stress response, to gain a more comprehensive understanding of the physiological mechanisms underlying stress-related eating.
“Future research should continue investigating stress-eating associations in adolescents and young adults and see if these effects track into adulthood and explore the implications for overweight and obesity in the future,” O’Connor said. “We should also explore the effects of different aspects of our cortisol profiles (e.g., the cortisol levels we release when we wake in the morning and across the day, not just in response to stress) and see if they are also related to stress-related eating vulnerability.”
The study, “Daily stress and eating behaviors in adolescents and young adults: Investigating the role of cortisol reactivity and eating styles“, was authored by Deborah Hill, Mark Conner, Matt Bristow, and Daryl B. O’Connor.