Aside from diabetes, polyphagia can be a symptom of the following hormone-related conditions: Hyperthyroidism or Graves’ disease: In these conditions, your thyroid releases too much thyroid hormone, which plays a significant role in regulating your metabolism (how your body transforms the food you eat into energy). Elevated levels of thyroid hormone speed up your metabolism, which means your body is using calories faster than normal. This can cause constant hunger and weight loss. Premenstrual syndrome (PMS): Premenstrual syndrome describes symptoms that show up one to two weeks before you start your period and return at the same time each month. One possible symptom is polyphagia. This is due to the spikes in the hormones estrogen and progesterone and decreased levels of serotonin (a neurotransmitter). Insulinoma: This is a rare tumor that forms in the endocrine cells in your pancreas — the cells that make the hormone insulin. The tumor causes your pancreas to release excess insulin, which results in low blood sugar. One of the main symptoms of hypoglycemia is insatiable hunger since your body needs sugar to get your blood sugar levels back in range.