Summary: A sudden fall in blood glucose during hunger can worsen mood and trigger stress responses.
Hunger and mood are closely linked, new research from the University of Guelph shows.
Researchers at the University of Guelph have found that an abrupt drop in glucose—what many people experience as that “hangry” feeling—can negatively affect mood and produce a measurable stress response. The work, published in the journal Psychopharmacology, used animal models to investigate how rapid changes in glucose metabolism influence emotional behaviour.
“We found evidence that a change in glucose level can have a lasting effect on mood,” said Professor Francesco Leri of the Department of Psychology. “Initially I was skeptical when people said they became irritable if they didn’t eat, but the data are clear: hypoglycemia is a potent physiological and psychological stressor.”
PhD student Thomas Horman, who led the study, added: “When people think about negative mood states and stress, they often focus on psychological causes and overlook metabolic factors. Our results show that poor eating habits can directly influence emotional state.”
The study induced hypoglycemia in rats by administering a glucose metabolism blocker, then assessed the animals’ behaviour in conditioned place avoidance tests. On one occasion the animals were injected with the glucose blocker and placed in a specific chamber; on another occasion they received a neutral injection and were placed in a different chamber. When given the choice later, the rats actively avoided the chamber associated with the hypoglycemic state.
“That avoidance behaviour is a clear sign of stress and anxiety,” Leri explained. “The animals avoid the chamber because they had a stressful, unpleasant experience there and want to avoid repeating it.”
Physiologically, the rats showed higher levels of corticosterone after experiencing hypoglycemia, indicating activation of the stress response. The animals also appeared less active when their glucose metabolism was blocked. To explore whether this reduced activity reflected depressed mood rather than only reduced muscle energy availability, the researchers administered a commonly used antidepressant. The antidepressant restored normal activity despite continued impairment of peripheral glucose supply, suggesting the behavioural change reflected altered mood or arousal rather than solely a lack of muscular fuel.
These findings suggest that disrupted glucose metabolism can influence mood through effects on both the hypothalamic–pituitary–adrenal (HPA) axis and monoamine systems in the brain. For people who struggle with anxiety or depression, the study highlights the potential importance of nutrition and meal patterns as part of a comprehensive treatment plan.
“Factors that contribute to depression and anxiety vary among individuals,” Horman said. “Knowing that nutrition can be a contributing factor means clinicians and patients can consider eating habits as part of prevention and treatment strategies.”
The research also offers insight into links between mood disorders and metabolic illnesses such as obesity, diabetes, bulimia and anorexia. Because hypoglycemia produced both behavioural avoidance and elevated stress hormones in the study, the authors plan to investigate whether repeated or chronic hypoglycemic episodes represent a risk factor for developing longer-term depression-like behaviours.
While missing a single meal may simply make you temporarily irritable, Horman cautions that chronic meal skipping could create a vicious cycle: poor eating leads to drops in mood, reduced mood suppresses appetite, and persistent exposure to that stressor could shift emotional baseline to a more constant negative state.
Source: Thomas Horman, University of Guelph. Published in Psychopharmacology.
Original research title: An exploration of the aversive properties of 2-deoxy-D-glucose in rats.
Abstract summary: Acute hypoglycemia alters arousal and produces negative mood-like effects. In a series of experiments with male Sprague-Dawley rats, the glucose antimetabolite 2-deoxy-D-glucose (2-DG) produced conditioned place avoidance, increased blood corticosterone, and suppressed locomotion. Feeding status influenced these outcomes. Treatment with clonidine (an α2 noradrenergic agonist) or bupropion (a monoamine reuptake inhibitor) attenuated avoidance and stress hormone responses, with bupropion also reversing locomotor suppression. These results suggest impaired glucose metabolism can negatively affect arousal and mood through HPA and monoamine system interactions.
This summary reports findings from controlled laboratory experiments in animals and describes potential mechanisms linking glucose metabolism and emotional state. It highlights the importance of consistent, balanced nutrition as one component that may influence mood and suggests further research is needed to determine how chronic metabolic challenges affect mental health in humans.