The Science Behind Why We Get Hangry

Everybody has at least some experience with being hungry and quite a few of us may have felt the low-mood and irritability that sometimes accompanies the sensation. The combination of being hungry and angry (hangry) can cause irrational rage. Chances are that you know at least one person who has experienced it. But what causes the unpleasant sensation of hanger?

The biology of being hangry

Food is vital for our survival. As mammals, we get our energy from the food we eat. In the same way a car requires petrol to power the engine; food is our fuel. When we eat, enzymes and bacteria in our body break food down into useable nutrients. Carbohydrates get broken down into simple sugars, including glucose. After a meal, our blood glucose levels peak and trigger our body to produce insulin.

Over time, the blood glucose levels drop to a point where the brain recognizes the need for more food.Many organs have energy stored and ready to use when blood glucose levels are low, but the brain is different. Our brains rely on glucose exclusively. The organ can account for up to 20% of our daily energy expenditure, even when resting. (1)

Although our heart and kidneys are more metabolically active than the brain, the brain’s larger size means that it takes up a larger share of the body’s energy requirements. When receptors in the brain detect low blood glucose, it panics and sends out signals to alert us to the need for food.

Hunger and stress hormones

When our body detects low glucose in our blood, several hormones are released to stabilise our blood glucose levels. Two of these hormones are cortisol and adrenaline/epinephrine. Both hormones are produced in our kidneys’ adrenal glands and are known as ‘stress hormones’ for their role in the fight-or-flight reaction.

Stress hormones helped keep us from becoming lunch for the big cats of our ancestors’ times by giving us the burst of energy needed to evade or fight that threat. The fight-or-flight reaction is hardwired in our biology for our survival. Yet, it is easy to see how these hormones could lead to a downturn in anyone’s mood. (2)

Cortisol can cause some people to get aggressive and low blood sugar can interfere with our brain’s ability to control our base impulses. These factors combined shows that there is indeed a biological explanation for hanger. It is tied to your body reacting to low blood sugar.

Recent research has shed some light on a gene that acts as a blueprint for producing a protein called neuropeptide Y. In studies, neuropeptide Y stimulated eating behaviour and regulated aggression and anger.  Ohio State University looked at how hanger can affect relationships. When married couples in the study had lower blood-sugar levels, they tended to feel angrier and more aggressive towards their partners. (3)

Avoiding hanger

Everybody experiences hunger in slightly different ways. Some people are more prone to getting hangry than others and if you tend to get hangry, there are ways to help bring it under control. Exercising regularly, eating multiple, small meals throughout the day and avoiding junk foods will keep the hunger at bay. For more information on the science behind what makes a person hangry, check the references below.


  1. About-axona.com. (2011). Brain energy metabolism: Metabolism of glucose in neuronal mitochondria — Axona®: Fuel the Brain. [online] Available at: http://www.about-axona.com/us/en/hcp/dcgm/normal-metabolism.html [Accessed 18 Mar. 2021].
  2. Naftulin, J. (2018). Why We Get Hangry, According to Science. [online] Health.com. Available at: https://www.health.com/nutrition/what-is-hangry [Accessed 19 Mar. 2021].
  3. ScienceDaily. (2014). Lashing out at your spouse? Check your blood sugar. [online] Available at: https://www.sciencedaily.com/releases/2014/04/140414154408.htm [Accessed 19 Mar. 2021].

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