Have you ever snapped angrily at someone when you were hungry? Or has someone snapped angrily at you when they were hungry? If so, you’ve experienced “hangry” (an amalgam of hungry and angry) — the phenomenon whereby some people get grumpy and short-tempered when they’re overdue for a feed.
But where does hanger come from? And why is it that only some people seem to get hangry? The answer lies in some of the processes that happen inside your body when it needs food.
The physiology of hanger:
The carbohydrates, proteins and fats in everything you eat are digested into simple sugars (such as glucose), amino acids and free fatty acids. These nutrients pass into your bloodstream from where they are distributed to your organs and tissues and used for energy.
As time passes after your last meal, the amount of these nutrients circulating in your bloodstream starts to drop. If your blood-glucose levels fall far enough, your brain will perceive it as a life-threatening situation. You see, unlike most other organs and tissues in your body which can use a variety of nutrients to keep functioning, your brain is critically dependent on glucose to do its job.
You’ve probably already noticed this dependence your brain has on glucose; simple things can become difficult when you’re hungry and your blood glucose levels drop. You may find it hard to concentrate, for instance, or you may make silly mistakes. Or you might have noticed that your words become muddled or slurred.
Another bodily response:
Besides a drop in blood-glucose concentrations, another reason people can become hangry is the glucose counter-regulatory response. Let me explain.
When blood-glucose levels drop to a certain threshold, your brain sends instructions to several organs in your body to synthesize and release hormones that increase the amount of glucose in your bloodstream.
The four main glucose counter-regulatory hormones are: growth hormone from the pituitary gland situated deep in the brain; glucagon from the pancreas; and adrenaline, which is sometimes called epinephrine, and cortisol, which are both from the adrenal glands. These latter two glucose counter-regulatory hormones are stress hormones that are released into your bloodstream in all sorts of stressful situations, not just when you experience the physical stress of low blood-glucose levels.
In fact, adrenaline is one of the major hormones released into your bloodstream with the “fight or flight” response to a sudden scare, such as when you see, hear or even think something that threatens your safety. Just as you might easily shout out in anger at someone during the “fight or flight” response, the flood of adrenaline you get during the glucose counter-regulatory response can promote a similar response.
Nature and nurture:
Another reason hunger is linked to anger is that both are controlled by common genes. The product of one such gene is neuropeptide Y, a natural brain chemical released into the brain when you are hungry. It stimulates voracious feeding behaviours by acting on a variety of receptors in the brain, including one called the Y1 receptor.
Besides acting in the brain to control hunger, neuropeptide Y and the Y1 receptor also regulate anger or aggression. In keeping with this, people with high levels of neuropeptide Y in this cerebrospinal fluid also tend to show high levels of impulse aggression.
As you can see, there are several pathways that can make you prone to anger when you’re hungry. Hanger is undoubtedly a survival mechanism that has served humans and other animals well. Think about it like this: if hungry organisms stood back and graciously let others eat before them, their species could die out.
And as we are all different across all of these factors, it’s little wonder there are differences in how angry people seem to get when they’re hungry.