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 thing that can become more difficult when you’re hungry is behaving within socially acceptable norms, such as not snapping at people. So 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, such as partners and friends. Sound familiar?