Have you ever had excessive hunger that doesn’t go away, regardless of how recently, or how much, you have eaten? This is referred to as polyphagia. Although it’s normally associated with diabetes, polyphagia actually has a few different possible causes, some of which are more persistent than others.
Broadly speaking, there are two main ways that polyphagia can be caused. The first is when a biological or physical factor causes the body to either need more or not receive enough nutrients.
In these cases, the abnormally large appetite is because the body is trying to acquire more fuel. The second type is when the body doesn’t or can’t receive the necessary signals to tell it that it’s full. These are more persistent hormone or genetic-related disorders.
Causes of Polyphagia
Polyphagia has a mix of physical, neurological, and mental causes that all present themselves differently. Since polyphagia is just one symptom, it is usually accompanied by other elements, depending on the underlying cause. While a doctor’s examination is always the best way to diagnose the cause of polyphagia, paying attention to any other symptoms that appear alongside it can help narrow things down:
Prader-Willi syndrome: This is a genetic disorder with a frequency of somewhere between one in 25,000 and one in 10,000 live births. The syndrome’s signature symptom is persistent polyphagia that tends to manifest around age two. Prader-Willi is actually the leading cause of morbid obesity in children. The syndrome has several physical symptoms as a result of the genetic defects. These include distinct facial features, such as almond-shaped eyes and a narrow temple, motor and speech development disabilities, intellectual disabilities, and underdeveloped sexual organs.
Klein-Levin syndrome: This is another rare genetic disorder that mainly affects adolescent males. The symptoms tend to come in waves, lasting for days to weeks before dissipating for months at a time. Klein-Levin’s signature symptom is the need for excessive sleep, sometimes up to 20 hours per day. While awake, behavioral changes can occur, such as polyphagia, irritability, lethargy, and a distinct lack of emotional responses (apathy). People with the disorder can become disoriented and hallucinations are not unheard of.
Hyperthyroidism: When the thyroid gland becomes overactive it will significantly accelerate your body’s metabolism. This creates numerous symptoms, including polyphagia. Rapid heartbeat, hand tremors, increased sweating, brittle hair, irritability, and the appearance of a goiter (enlarged thyroid) on the neck are all additional signs that can present with hyperthyroidism.
Anxiety, depression, or stress: All three of these are capable of causing forms of polyphagia either as a psychological coping mechanism or as a result of hormone disruptions, depending on the underlying cause.
Hypoglycemia: Polyphagia is a common symptom when the body’s blood sugar levels drop dangerously low. The cause of the drop can be attributed to not eating for a long period of time, hormone disorders, or major organ diseases. But the signs of hypoglycemia remain relatively constant. In addition to polyphagia, hypoglycemia causes headaches, irritability, confusion, dizziness, sweating, and pale skin. It can lead to unconsciousness, coma, loss of coordination, and numbness in the mouth and tongue.
Pregnancy: The nutritional demands of the fetus and hormone adjustments of pregnancy can cause the mother to experience polyphagia. Incidentally, polyphagia is also a reported symptom of PMS for similar hormonal reasons.
Metabolism: Everyone has a different metabolism level and experiences hunger at different levels throughout the day. High periods of physical activity can cause a short period of polyphagia.
Polyphagia and Diabetes
As mentioned above, hypoglycemia is a possible cause of polyphagia. With diabetes, the body is unable to properly process sugar as a result of either having too little insulin or actually developing a resistance to insulin. The inability to convert food into energy leaves the cells perpetually starved, resulting in hypoglycemia that causes polyphagia. Diabetes is one of the most common causes of polyphagia but, as you have seen, it is not the only one. Polyphagia is one of three cardinal signs for type-1 diabetes. The other two are polydipsia (excess thirst) and polyuria (excess urination).
The kidneys filter blood to produce urine. When there is excessive sugar in the blood, this translates to excess sugar in the urine. The sugar then draws in water from the surroundings to further increase the volume of urine. Since the amount we drink each day naturally affects our urine output, it takes the frequent passage of three or more litres per day to count as polyuria.
Polyuria has many other possible causes instead of just diabetes. Certain urinary tract or kidney infections can cause excessive urination, as can hyperthyroidism, vitamin D toxicity, or certain cardiac problems. The mechanism by which excess sugar causes polyuria—called osmotic diuresis—can also occur with other substances, such as urea, a compound used in certain food and medical products.
The excess thirst of polydipsia, like the hunger associated with polyphagia, is not usually abated by drinking. In cases of diabetes, the increased thirst is linked to the heightened water loss caused by polyuria. Although type 1 diabetics can present without polyphagia, polydipsia and polyuria usually appear together.
Since the body uses water for numerous other purposes, there are additional possibilities that can cause polydipsia. Anything that causes a loss of blood volume, such as major bleeding, can create a state of excess thirst as the body tries to replenish its fluids. Zinc deficiency is another possible cause as well. Polydipsia is also known to present in certain cases of schizophrenia.
All three signs—polyphagia, polyuria, and polydipsia—can also occur as a side effect of several medications. If you experience any of the three while on a medicine, talk to your doctor about it being a possible cause.
Addressing polyphagia first requires that the underlying cause is properly identified. Once that happens, additional steps can be taken. In some cases, like from metabolism or pregnancy, little action is needed other than to keep yourself fed and wait for it to pass. For genetic disorders or hyperthyroidism, hormone (or anti-hormone) medications are used to help alleviate the symptoms. In extreme cases of hyperthyroidism, surgery may be needed to excise part of the thyroid. Diabetes treatment requires a combination of diet adjustments, blood sugar monitoring, and taking your insulin regularly.
Sources for Today’s Article:
“Hyperthyroidism (overactive thyroid),” Mayo Clinic web site, November 20, 2012; http://www.mayoclinic.org/diseases-conditions/hyperthyroidism/basics/symptoms/con-20020986.
“When Your Blood Sugar Gets Too Low,” WebMD web site; http://www.webmd.com/diabetes/diabetes-hypoglycemia, last accessed August 24, 2015.
“Kleine-Levin Syndrome,” WebMD web site; http://www.webmd.com/mental-health/kleine-levin-syndrome, last accessed August 24, 2015.
“Polyuria – Frequent Urination Symptoms and Causes,” Diabetes.co.uk; http://www.diabetes.co.uk/symptoms/polyuria.html, last accessed August 24, 2015.
“Prader-Willi Syndrome,” Mayo Clinic web site, April 17, 2014; http://www.mayoclinic.org/diseases-conditions/prader-willi-syndrome/basics/symptoms/con-20028982.