Many consider hunger a condition, rather than the collection of conditions that it comprises. Hunger is more than simply an empty stomach; it is both a physiological and psychological response to numerous changes in the body. Although these changes are usually in response to the complete metabolism of ingested food, hunger can also occur as a result of habit, exposure to palatable food, or during social occasions. However, despite the cause of hunger, the general discomfort that invariably ensues can often cause irritability in those that experience it.
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Physiological Effects of Hunger
Irritability, or "grouchiness" associated with hunger is most often due to its physiological effects. Once a stomach is empty following the complete metabolism of ingested food, gas begins accumulating. This builds pressure in the stomach, causing cramping. These cramps can become more pronounced as the muscles that line the stomach walls contract to guide the gas into the intestines for expulsion. These contractions, called peristalis, are the same used to churn food with gastric juices during digestion. In addition to the abdominal discomfort associated with hunger, other reasons for irritability include fatigue, gum inflammation, bloating and dry as well as itchy skin.
Psychological Effects of Hunger
Metabolism causes rises in blood serum glucose levels, which is the primary source of fuel for the brain, muscles and organs of the body. Accordingly, glucose levels drop once there is no longer any food to metabolize. Just as this glucose reduction causes fatigue and weakness, it also causes psychological disparities. Specifically, inattentiveness, dizziness and general frustration usually follow the onset of hunger, significantly contributing to grouchiness.
Hormones Associated with Hunger
Numerous hormones contribute to the experience of hunger. For example, the pancreas produces insulin, which causes glucose in the bloodstream to transfer into the cells that require energy. It also produces glucagon, which causes the liver to release stored glucose into the bloodstream as needed. However, both of these hormones also stimulate the hypothalamus in the brain, which spurs many other physiological reactions, such as persitalis and the general desire to eat. Other hormones, like ghrelin and orexin, which are secreted by organs throughout the digestive tract, affect both satiety and sleep patterns. Imbalances in these hormones, particularly due to prolonged hormone episodes, can detract from overall well-being, causing irritability.