Great question. Dr. Deena Adimoolam, a professor of Endocrinology, Diabetes, and Bone Disease, provides an explanation "When we do not eat, blood sugar goes low," she said. When our blood sugar gets low, the hormones cortisol and epinephrine are released in an attempt to raise it back to normal levels. But those hormones are also linked to irritability. In addition, the hormone Neuropeptide Y helps create a hungry feeling when your body needs more food, but it is also linked to aggression.

Reference: Naftulin, J. (June 13, 2018). Why we get hangry, according to science. Health. Retrieved from https://www.health.com/nutrition/what-is-hangry

It can be both. When people are deprived of food they naturally become hungry. This is a physical process. But people eat for a variety of reasons other than the need to survive, such as because of psychological stress. for comfort, because they are bored, out of habit, in response to a cue (e.g., seeing an advertisement for a food product), for comfort, to celebrate, etc.

For sustained results, try to partake in nourishing foods (e.g., veggies, whole grains, foods high in protein) instead of reaching for a candy bar. If you need something quick, grab a protein bar instead.

Most children are always on the go. Their bodies need nutritious food for their organs and systems. The best way to help children recognize that they are hangry, is to point it out to them. When you notice they are getting cranky and irritable, ask them if they are hungry. Then explain to them that our brains need fuel to help us control our emotions, including angry feelings. We get the fuel from the food we eat. Healthy foods with fiber and protein (e.g., veggies, whole grains) keep the "gas tank" fuller for a longer time period. Always be sure to have healthy meals and snacks on hand. When our children were young, we had a rule that they would eat five servings of fruits and veggies each day, but we let them choose the fruits and veggies.

Depletion theory predicts that willpower can become depleted when people use it throughout the day. In an influential early demonstration of this principle, participants arrived at the laboratory having skipped a meal, so most were hungry. The researchers baked fresh chocolate chip cookies, which filled the room with a delicious and tempting aroma. Each participant was seated at a table in front of a stack of these cookies and delectable chocolates, as well as a bowl of radishes. In the important condition, the experimenter told each participant, “You have been assigned to the radish condition,” which meant they were supposed to eat only radishes. The experimenter then left the participant alone for five minutes to eat. This task required considerable willpower to resist the tempting chocolates and cookies and eat only the radishes as instructed. In other conditions, participants were permitted to eat cookies and chocolate instead of radishes, or no food was present at all. After this, the participants were set to work on some difficult (actually unsolvable) problems, and the researchers measured how long people kept trying before they gave up, because willpower is also needed to keep trying when you feel discouraged and want to quit. Consistent with depletion theory that willpower gets used up, the participants in the radish condition quit sooner than participants in the other two conditions. Thus, resisting temptation (in the form of chocolates and cookies) used up some willpower, so those participants had less left over to help them keep working on the frustrating puzzles.

Source: Baumeister, R. F., Bratslavsky, E., Muraven, M., & Tice, D. M. (1998). Ego depletion: Is the active self a limited resource? Journal of Personality and Social Psychology, 74, 1252–1265.

Yes, it is definitely possible to control feeling "hangry" (hungry + angry). The best way is by eating healthy foods. Although sugary foods and beverages provide glucose the brain needs to regulate emotions, you get a quick spike in glucose followed by a quick decline. It is better to eat foods like vegetables and whole grains, which keep glucose levels higher for longer. If you feel yourself getting "hangry" and you don't have time to eat a healthy meal, grab a protein bar.

For some, being hangry can become a chronic condition if they always have difficulty obtaining food. The best way to keep glucose levels higher longer periods of time is by eating veggies and whole grains, but not all people can afford to buy such expensive food. If one can afford to buy protein bars, eat one of those.

Anger is an emotional response to a real or imagined threat or provocation. Anger can range in intensity from mild irritation to extreme rage. One threat is lack of food. But anger can be caused by many factors other than lack of food, such as frustration, insults, social rejection, and unpleasant events (e.g., hot temperatures, loud noises, irritants in the air, unpleasant odors, crowding, stress).

Our research suggests that hangry people lash out aggressively at both strangers and loved ones. Of course, we don't want to hurt the ones we love. Thus, when you have a discussion about a sensitive topic with a loved one, be sure not to do it on an empty stomach.

Sources:

DeWall, C. N., Deckman, T., Gailliot, M. T., & Bushman, B. J. (2011). Sweetened blood cools hot tempers: Physiological self-control and aggression. Aggressive Behavior, 37(1), 73-80. DOI: 10.1002/ab.20366

Bushman, B. J., DeWall, C. N., Pond, R. S. Jr., & Hanus, M. D. (2014). Low glucose relates to greater aggression in married couples. Proceedings of the National Academy of Sciences (PNAS), 111(17), 6254-6257. DOI: 10.1073/pnas.1400619111

We have not found gender differences in our research. Hungry people tend to become angry regardless of their gender. However, there are gender differences if anger is expressed as aggressive behavior. Males and females tend to use different forms of aggression. Physical aggression is higher in males than females, whereas indirect aggression (e.g., gossiping, spreading rumors) is higher in females than males. Verbal aggression is similar in males and females.

Yes, some people are more prone to hungriness, In particular, people who have trouble metabolizing glucose (e.g., diabetics) are especially prone to becoming hangry. People with glucose-6-phosphate dehydrogenase deficiency lack an enzyme related to glucose metabolism. It is the most common enzyme deficiency in the world and is especially common among individuals with diabetes.

People fast for a number of reasons (e.g., religious, weight loss, health). Fasting is different from dieting. Rather than cutting calories, people avoid calories all together (or severely cut back) for a certain amount of time. Before you fast, you should talk to your doctor. Research shows that certain types of fasting may help improve your cholesterol, blood pressure, glucose levels, insulin sensitivity, and other health issues. There are three main types that doctors have studied: (1) time-restricted feeding, (2) alternate-day fasting, and (3) modified fasting. Time-restricted fasting means you do all your eating in a certain stretch of the day, often around 8-12 hours. Alternate-day fasting means you go without food for 24 hours, and then "feast" afterwards. Modified fasting means that you eat around 20% to 25% of the amount of food you normally eat on scheduled fast days. For example,, the 5:2 diet requires 2 days a week (not in a row) of 24-hour “fasting” except for a very light meal. On the other 5 days of the week, you can eat whatever you want. If your doctor advises fasting, be aware that you will become hungry, and therefore could become hangry. However, studies show that fasting might help people with diabetes or prediabetes control blood sugar, improve insulin sensitivity, and lose weight.

Source: https://www.webmd.com/diet/obesity/ss/slideshow-fasting-overview

When you cut out carbohydrates, the body begins burning more fat for fuel. This can lead to ketosis, which may make losing weight easier because you feel less hungry. It is important to eat vegetables, which contain fiber and other important nutrients. Beans and legumes are also high in protein and fiber. Foods that are high in fiber and protein keep glucose levels higher for longer periods. However, ketosis may also cause temporary irritability as well as other symptoms (e.g., headaches, nausea, sleeping problems) for some people.

Source: https://www.webmd.com/diet/ss/slideshow-high-protein-diet

My expertise is on anger and aggression rather than nutrition. The part of our brain just behind our forehead, called the pre-frontal cortex, is in charge of executive functions, such as controlling our emotions. The emotion people have the most difficulty controlling is anger. Glucose provides fuel for the brain. Glucose is a simple sugar that circulates in the blood as blood sugar. Glucose is the most important source of energy in all organisms. With a fuel tank full of glucose, the brain is better able to regulate angry feelings and aggressive impulses. My understanding is that the body can use fat for fuel when there is limited access to glucose (blood sugar), but glucose is the preferred fuel source.

Yes, hungriness can be a sign of poor glucose control. Research from our lab found that poor glucose metabolism was linked with anger and aggression. One study found that diabetic symptoms were related to aggressiveness.] Using data from all 50 states in the U.S., another study found that diabetes rates from each state were positively related to violent crime rates from each state. Another study found that rates of glucose-6-phosphate dehydrogenase were positively related to violence rates around the world. People with glucose-6-phosphate dehydrogenase deficiency lack an enzyme related to glucose metabolism. It is the most common enzyme deficiency in the world and is especially common among individuals with diabetes.

Source: DeWall, C. N., Deckman, T., Gailliot, M. T., & Bushman, B. J. (2011). Sweetened blood cools hot tempers: Physiological self-control and aggression. Aggressive Behavior, 37(1), 73-80. DOI: 10.1002/ab.20366

Hunger is an unpleasant a feeling of discomfort or weakness that is caused by lack of food. When people are deprived of food, they want to eat. Most researchers would not classify hunger as an emotion. However, hunger can lead to the emotion anger. Paul Ekman and his colleagues have identified six basic emotions that can be reliably inferred from facial expressions: anger, surprise, disgust, happiness (or joy), fear, and sadness.

The most reliable measure of low blood sugar is to take a reading with a blood glucose meter. But one can also experience symptoms of low blood sugar. Each person's reaction to low blood sugar is different, and each person should try to identify their own symptoms.. According to the American Diabetes Association. some symptoms of low blood sugar include:

Feeling shaky Being nervous or anxious Sweating, chills and clamminess Irritability or impatience Confusion Fast heartbeat Feeling lightheaded or dizzy Hunger Nausea Color draining from the skin (pallor) Feeling sleepy Feeling weak or having no energy Blurred/impaired vision Tingling or numbness in the lips, tongue, or cheeks Headaches Coordination problems, clumsiness Nightmares or crying out during sleep Seizures

Source: https://www.diabetes.org/diabetes/medication-management/blood-glucose-testing-and-control/hypoglycemia

Research suggests that low glucose is the primary mechanism. According to Dr. Deena Adimoolam, a professor of Endocrinology, Diabetes, and Bone Disease, provides an explanation, "When we do not eat, blood sugar goes low," she said. When our blood sugar gets low, the hormones cortisol and epinephrine are released in an attempt to raise it back to normal levels. But those hormones are also linked to irritability. In addition, the hormone Neuropeptide Y helps create a hungry feeling when your body needs more food, but it is also linked to aggression.

Source: Naftulin, J. (June 13, 2018). Why we get hangry, according to science. Health. Retrieved from https://www.health.com/nutrition/what-is-hangry

I could find no direct research on this topic. However, I did find a large body of potentially relevant indirect research. In particular, people in high stress jobs are prone to lash out at others aggressively. It takes a lot of self-control to avoid lashing out at others in stressful situations. The part of our brain just behind our forehead, called the pre-frontal cortex, plays a key role in controlling our emotions, including angry responses to stress. . Glucose provides fuel for the brain. Glucose is a simple sugar that circulates in our blood and provides us energy. With a fuel tank full of glucose, the brain is better able to regulate angry feelings and aggressive impulses. Thus, people in high stress jobs should take special care to avoid becoming hangry by eating healthy food. Keep a few protein bars handy just in case.

Some people use sugary foods in ways that aren't healthy. Some warning signs include craving sugar, losing control, and eating more than you planned. Sugar quickly turns into glucose in your bloodstream, which your body needs as fuel to regulate emotions, including anger. Your blood sugar levels spike, but then quickly plummet. It is like a roller coaster with ups and downs. It is much better to eat foods that are high in fiber and protein, because they keep glucose levels higher for a longer period of time.