Feeling hungry can alter our mood. Various studies have shown that hunger can make us more negative, irritable and aggressive. The emotional impact of hunger can even affect our decision-making. This was demonstrated by a 2011 Israeli study that gave rise to what is known as the “hungry judge effect.” What the study’s authors observed was that the severity of judges’ sentences increased as lunchtime approached, only to become significantly more lenient after the lunch break. This close relationship ultimately led to the invention of a term to refer to this phenomenon: “hangry” (a combination of “hungry” and “angry”). It was added to the Oxford English Dictionary in January of 2018.
The explanation traditionally given for the relationship between hunger and mood has been purely physiological. “Several studies suggest that aggression does not arise spontaneously, but is modulated by the brain’s energy availability and previous nutritional experience. Self-control – key to inhibiting aggressive behavior – consumes large amounts of glucose. So, when [glucose] is scarce, or [when] metabolism is altered, the ability to regulate impulses decreases,” explains Marta Garaulet, a professor of Physiology and Physiological Bases of Nutrition at the University of Murcia, in Spain.
This relationship, the expert maintains, isn’t unique to our species. Experimental studies in fruit flies, for example, have shown that food deprivation for more than a day significantly increases aggression among males, even as their physical condition deteriorates. “In this case, hunger increases the perceived value of the food resource and the motivation to defend it, resulting in more conflicts and confrontations. This demonstrates that the so-called ‘hangry’ phenomenon has deep biological roots shared across species,” Garaulet argues.
And indeed, as research with fruit flies demonstrates, not eating isn’t only an inconvenience, but also a biological threat. When blood glucose levels drop, the body activates the so-called “stress axis” – the hypothalamic-pituitary-adrenal (HPA) axis – which triggers the release of cortisol: “In evolutionary terms, the message is clear: [when] energy is lacking, we must react.”
The chrononutrition expert adds that cortisol has an adaptive function: it increases available blood glucose, mobilizes energy reserves and keeps the brain “alert.” The problem is that, at the same time, it reduces non-priority functions – such as empathy and emotional regulation – while facilitating defensive, impulsive, or aggressive responses. It also makes us interpret our environment as more hostile.
“Cortisol doesn’t cause aggression on its own, but it lowers the threshold at which we react with anger or violence. In combination with low glucose and reduced self-control, it explains very well why hunger makes us more susceptible to conflict,” Garaulet reflects.
Beyond the physiological explanation
Having accepted these physiological bases for the relationship between hunger and a worse mood, various studies are now attempting to find explanations that go beyond the lack of glucose and the increase in cortisol levels. For instance, a study published in 2018 in the journal Emotion, from the American Psychological Association, explored whether the negative feelings caused by physiological changes induced by hunger could, in turn, bias our perception of the world around us.
Based on three experiments in which the authors systematically manipulated people’s hunger levels, contextual cues and self-awareness, it was discovered that simply being hungry wasn’t enough to make someone “hangry.” Rather, two other key factors are also involved.
“First, you have to be in a negative or unpleasant state. People don’t seem to get so hangry in neutral or pleasant contexts. If you’re having a good time with friends, but you’re hungry, you probably won’t become irritable unless something annoying or uncomfortable happens. But if you’re in an unpleasant or irritating situation, like a massive traffic jam, and you’re also hungry, then it’s a perfect scenario for those feelings to arise,” says Jennifer MacCormack, an assistant professor in the Department of Psychology at the University of Virginia (UVA).
Second, she adds, self-awareness is crucial. According to the researcher, people become hangry when they let themselves be absorbed by what’s happening around them (the traffic jam, for example), instead of recognizing that the real source of their negativity is hunger. “When we asked participants in our studies to pay attention to their emotions, the hangry bias disappeared: they stopped being so harsh or critical of others and even said that they felt less irritable and angry, despite being hungry,” she describes.
A similar conclusion was reached by another recent study, which came out in late-2025 in eBioMedicine, published by The Lancet. It combined continuous glucose monitoring over four weeks with twice-daily logs completed by participants on their smartphones. They assessed their hunger or satiety levels, as well as whether they felt happy or sad. With this information, the authors confirmed (as expected) that lower glucose levels were associated with a worse mood. However, they observed that this association was also explained by the hunger assessments collected. “In other words, participants were only in a worse mood when they consciously perceived their lack of energy as hunger… not because of [subconscious signalling of] a lack of glucose as an energy source,” explains Nils Kroemer, a researcher in the Department of Psychiatry and Psychotherapy at the University Hospital of Tübingen (Germany) and a professor of Medical Psychology at the University of Bonn.
The authors, in fact, found that some people were more susceptible to feeling hangry. They also found that some women were better able to perceive hunger in conjunction with changes in glucose levels and, therefore, reported fewer mood swings. “This suggests that being more aware of bodily signals can improve emotional regulation by helping to control mood changes more effectively,” he reflects.
Based on the results of these studies, both researchers point out that feeling hangry is something that can be modulated by making yourself aware that you’re hungry, and that this is skewing how you see the world. “Our data suggests that hungry people aren’t wild beasts: when we recognize the true source of our negative emotions, we can avoid acting impulsively under the influence of that state,” Jennifer MacCormack says.
In such situations, the UVA professor recommends “trying to focus on positive aspects of [your] environment and putting yourself in a more pleasant situation until you can eat something.” For example, in the case of the aforementioned traffic jam, you could listen to relaxing music. Nils Kroemer, for his part, emphasizes the importance of maintaining a regular meal schedule, which helps avoid unpleasant surprises for the body, since conscious hunger often appears when we skip a meal that we expected to eat. “If we never eat breakfast, we don’t feel as hungry in the morning; [this is different if we suddenly] skip breakfast on a particular day,” he concludes.
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