When hunger and anger collide, it makes for the very real 'hangry'

Some swear that hanger — the intense anger or uncomfortable emotions that can come with being hungry — is real. Some people say it's all in your head. It turns out, they both may be right.

What we eat, or don't eat, affects our brains and emotions in ways researchers are just starting to understand. Several studies, including a small one from Britain, have found that feeling hunger in your belly is associated with negative-feeling emotions. And research from the past decade increasingly shows that food can change emotional states, as well as influence behavior and decision-making.

In 2018, the word "hangry" was even added to the Oxford English Dictionary, indicating its popular acceptance as a phenomenon. But what causes hanger, and why do some people get hangry and some don't?

Hormonal hanger

New science on hanger and the brain, which I explore in my new book, "Eat & Flourish," shows that food and emotional well-being are inextricably entwined. Research is focused mainly on two mechanisms that compose the body's main communication system, hormones and neurons.

First, hormones send messages all over the body by traveling through your blood. Hanger may happen in part because hunger often coincides with a drop in glucose, which can create hormonal changes in the body that affect brain functioning.

When blood glucose is low, you can raise it by eating something. When curbing hormonal hanger, it's best to reach for something with protein, fiber and complex carbohydrates. Eating simple carbohydrates alone can send blood sugar soaring, which can make you jittery, followed by a blood sugar crash.

But that flood of cortisol and adrenaline in the bloodstream keeps us on high alert to threats. That high alertness, combined with being hungry, can result in the irritability frequently associated with hanger. Some bodies are more reactive than others to these hormones, so hanger can be extreme or not, depending on your physical reaction.

Checking hunger and anger

The second way that research shows hanger can happen is through neurons, the specialized cells all over your body that communicate with each other. The nervous system sends messages around your body faster than the blink of an eye, much faster than hormones.

Specifically, hanger researchers (yes, that's a thing) have identified neuron activity in the brain's hypothalamus, a region that coordinates hunger and emotion, among other nervous system functions. Hunger activates these brain cells, known as AgRP neurons for the protein they express.

But researchers such as Amber Alhadeff at the Monell Chemical Senses Center in Philadelphia colloquially call these neurons "hangry neurons."

The surprise was that alongside hunger, the cells also signal a "negative valence," an uncomfortable emotion usually associated with fear, anxiety and anger that the mice worked to avoid.

It was different from hunger, but happened alongside it. And then, when the mouse ate, AgRP neurons immediately calmed down and simultaneously stopped sending both hunger and negativity signals.

Eating and the taste of food itself can be intensely pleasurable. Alhadeff wanted to make sure the calming effect wasn't just from a burst of flavor. She tested to see if injecting food directly into a mouse's stomach had the same effect. It did.

Gut-brain connection

Alhadeff says calming hanger may have to do with our gut sense, as hangry neurons are just one of numerous connections between the gut and the brain.

The gut has its own nervous system, called the enteric nervous system and known as "the second brain," that senses food and nutrients even when they don't go through the mouth.

As Alhadeff explains, "we've discovered that you really need that gut signaling to have long, sustained reductions in AgRP activity." So trying to address hanger with a Diet Coke is futile. "In the absence of that gut signaling, you really don't shut off these hunger neurons," she said.

Alhadeff hypothesizes that hangry neurons are remnants of a time not so long ago when most humans had to forage for food, and we needed more than just hunger to motivate us to find something to eat. Most of us don't forage for food anymore. But this group of neurons still has a lasting impact.