Why do people get 'hangry'? The answer is not what you think

Feeling “hangry” is such a familiar experience that most people barely question it. A missed meal, a long meeting, a late lunch – and suddenly everything feels sharper and more irritating. Many assume the cause sits deep in the biology of falling glucose.

A new study challenges that idea in a very direct way. The researchers show that mood does not fall because glucose quietly drops. Mood falls because hunger becomes a conscious signal that the person notices.

Each participant in the study wore a continuous glucose monitor for four weeks. Every day, a phone app asked about hunger, fullness, and mood. These brief check-ins produced thousands of snapshots of daily life.

The researchers did not try to manipulate the participants. They simply watched what happened in the real world.

Hunger shapes mood

The main result appeared quickly. Glucose can fall without changing mood at all. Mood only shifts when a person also feels hungry.

“When glucose levels drop, mood also deteriorates. But this effect only occurs because people then feel hungrier,” said Dr. Kristin Kaduk of University of Tübingen.

“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.”

This finding places conscious awareness at the center of the hangry experience. Glucose sets the stage, but hunger delivers the emotional hit. If someone does not feel hungry, the low glucose does not bother them.

Visual summaries in the study illustrate this pattern. The line from glucose to mood fades when hunger enters the model. Hunger acts like a filter. Mood responds to the feeling, not the number.

Keeping emotions steady

The study also explored interoception. Interoception means the ability to sense internal states like hunger, thirst, discomfort, or calmness.

The strength of this ability varies from person to person. Some individuals pick up small changes very fast. Others only notice the stronger signals.

The research team discovered something interesting. People with sharper interoception showed fewer mood swings during the four weeks. Their emotional states remained steadier, even on days with large shifts in glucose.

“Our results suggest that consciously feeling your own body can act as a kind of buffer for your mood,” noted Professor Nils Kroemer. “A good sense of the body’s own signals seems to help maintain emotional stability, even when energy levels fluctuate.”

This shifts the focus from biology alone to the combination of biology and awareness. Internal signals matter, and the recognition of those signals matters even more.

Patterns in real life

Past research often used controlled drinks, short tasks, or fixed meals to study how glucose might influence mood. Those experiments produced mixed results.

Some showed a clear effect, while others found none. These inconsistencies make sense, because real life does not follow the structure of a laboratory session.

The new study observed people in their everyday routines instead of controlled settings. Meals changed from day to day. Sleep patterns shifted and activities varied.

Even with all this natural movement, one finding stayed consistent. Hunger predicted mood, and glucose only mattered when the person actually felt hungry.

The study group included people with different body mass indexes, different levels of insulin sensitivity, different activity patterns, and different daily habits. None of these differences changed the main pattern.

Across a wide range of bodies and lifestyles, the same result held true. Hunger guided mood.

Understanding mood and metabolism

The research also points toward future work in mental and metabolic health. Conditions such as depression and obesity often involve disrupted metabolic processes.

The researchers suggest that improving the ability to sense hunger and other internal cues may support more stable emotions.

Professor Kroemer highlights possible tools for future research. He mentions interoception training and non invasive stimulation of the vagus nerve.

The vagus nerve connects the organs to the brain and shapes how internal signals become conscious.

This approach does not aim to change glucose directly. Instead, it aims to improve the clarity of internal awareness.

People may respond differently when they recognize early hunger rather than feeling blindsided by a sudden shift in mood.

Why hunger hurts

The study gives a simple takeaway. The emotional drop during hunger does not come from silent changes in glucose.

The drop comes from the moment hunger becomes a felt experience. The mind creates meaning out of that signal, and the mood follows.

This idea fits well with psychological theories that describe emotions as interpretations of bodily states. A stomach cue becomes an emotional cue. A small change in energy turns into a shift in perception.

This understanding can help in practical ways. Someone who notices early hunger may prevent a sharper mood swing. Someone who pays attention to small internal cues may feel steadier throughout the day.

The researchers hope to explore these ideas in clinical groups next. Many people who struggle with mood also struggle with metabolic regulation.

This connection between body awareness and emotional balance may open new paths for therapy.

The study is published in the journal EBioMedicine.

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