When our stomachs are empty, we may get cranky or snap at the people around us. We’re hangry, we may exclaim, to excuse our mischief. But what’s really going on when this storm of hunger and anger hits?
The term hangry was likely first used in 1918 (in a letter by journalist and writer Arthur Ransome), but it has swept popular culture in recent decades, featured in everything from a Snicker’s ad to an Olympic snowboarder’s viral tweet.
Scientists are only now beginning to catch up. One thing they haven’t fully understood is how this close relationship between anger and hunger works in the brain: Do drops in glucose levels in the blood trigger changes in mood through subconscious or conscious processes?
To answer this question, a team of German researchers recently tracked how glucose levels, feelings of hunger, and mood interacted in 90 healthy adults over a period of four weeks. The scientists gave participants glucose monitors to wear and asked them to regularly answer questions about hunger, satiety, and mood via a smartphone app.
The results suggest that hangriness is indeed real: The more hungry participants were, the worse their mood.
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But surprisingly, the researchers found that hunger-related shifts in mood depended on conscious sensing of the body’s internal state, not unconscious processes. In other words, it’s all about how your brain interprets the signals coming from your gut.
“When glucose levels drop, mood also deteriorates. But this effect only occurs because people then feel hungrier,” explained co-author Kristin Kaduk, postdoctoral researcher at the University Hospital for Psychiatry and Psychotherapy in Tübingen, Germany, in a statement. “In other words, it is not the glucose level itself that raises or lowers mood, but rather how strongly we consciously perceive this lack of energy.”
Separately, Kaduk and her colleagues also found that the participants who were better able to read their own bodily signals, a sense known as interoception, seemed to experience fewer mood swings, though not higher average mood. Differences in metabolic health—such as body mass index and insulin resistance—didn’t play much of a role in this pattern. They published their results in eBioMedicine.
The researchers suggest that the study may point to a larger relationship between metabolic sensing, interoceptive accuracy, and mood disorders. The human body needs food to survive, of course. Glucose supplies energy for essential processes, including mental health. And links between metabolic issues and mood disorders have often cropped up in the research. Poor interoception has also been linked to higher body mass index.
“Many diseases such as depression or obesity are associated with altered metabolic processes,” said Nils Kroemer, co-author of the study, psychiatrist and research professor of medical psychology at the University of Bonn. “A better understanding of how body perception and mood are related can help improve therapeutic approaches in the long term—for example, through targeted training of interoception or non-invasive stimulation of the vagus nerve, which connects the organs to the brain and influences interoception.”
Interoception is something you can get better at, through mindfulness, deep breathing, body scans, and efforts to link sensations to emotions, research suggests. Perhaps with a little consistent practice, you can head off your next episode of hangriness. 
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