Hangry, wordplay that combines hungry and angry, is a phenomenon whereby some people get short-tempered and grumpy when they’re overdue for a feed.
The carbohydrates, proteins, and fats in everything we consume are digested into simple sugars (like glucose), amino acids, and free fatty acids. These nutrients pass into our bloodstream from where they are distributed to the organs and tissues, and utilized for energy.
As time passes after a 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. Unlike most other organs and tissues in our body, the brain is critically dependent on glucose to do its job.
Simple things can become difficult when we’re hungry and our blood glucose levels drop. For instance, it becomes harder to concentrate, and easier to make silly mistakes. Our words could also become muddled or slurred.
It also becomes hard to behave within socially acceptable norms, such as not snapping at people. While you may be able to conjure up enough brain power to avoid being grumpy with important colleagues, you may let your guard down and inadvertently snap at the people you are most relaxed with or care most about, like partners and friends.
Besides a drop in blood-glucose concentrations, another reason people can become hangry is the glucose counter-regulatory response. When blood-glucose levels drop to a certain threshold, the brain sends instructions to several organs in the body to synthesize and release hormones that increase the amount of glucose in your bloodstream.
These four main glucose counter-regulatory hormones are the growth hormone from the pituitary gland; glucagon from the pancreas; and two from the adrenal glands, adrenaline and cortisol. 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.
Another explanation why 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 need nourishment. It stimulates voracious feeding behaviors by acting on a variety of receptors in the brain, including one called the Y1 receptor.
Neuropeptide Y and the Y1 receptor, not only control hunger, they also regulate anger. In keeping with this, people with high levels of neuropeptide Y in their cerebrospinal fluid tend to show high levels of impulse aggression.
Hanger is undoubtedly a survival mechanism that has served humans and other animals well. While many physical factors contribute to hanger, psychosocial factors also have a role. Culture influences whether you express verbal aggression directly or indirectly, for instance. Since everyone is different across all of these factors, it’s little wonder there are distinctions in how angry people seem to get when they’re hungry.