"Food is the first necessity of the people," and appetite, as one of the three basic human instincts, is an important indicator of the condition of the five internal organs. Since the human body is an integrated whole, the malfunction of any organ can lead to an abnormal appetite. Therefore, appetite can be seen as a mirror of health.
Normal eating is supposed to be an enjoyment, but when it becomes a burden, it is known as anorexia. In daily life, it is common to hear people say things like "I have no appetite" or "I don't feel like eating." So, what diseases might these symptoms signal?
Occasional loss of appetite is often a sign of a deficiency in the spleen and stomach, while persistent anorexia is frequently a sign of atrophic gastritis, and could even indicate stomach cancer or pancreatic cancer. Persistent anorexia can also be a sign of liver depression, psychiatric disorders, or depression. If anorexia is accompanied by nausea, it is often a sign of renal failure uremia, late-stage diabetic acidosis, or ketosis. Hypothyroidism can also lead to a decreased appetite to varying degrees.
The opposite of a poor appetite is a ravenous appetite. If you find yourself suddenly having a voracious appetite, it is often a sign of "excessive fire" in the stomach. Hyperthyroidism and manic psychosis can also cause a significant increase in appetite. If there is a craving to eat inedible substances, such as candles, coal, dirt, or uncooked rice, it is often a precursor to infantile malnutrition or psychiatric disorders.
A healthy person's mouth is neither dry nor thirsty, and they can taste their food, a state known as "harmony in the mouth," which indicates normal stomach qi and sufficient body fluids. Conversely, when the body's yin and yang are out of balance and the internal organs are diseased, this sense of "harmony in the mouth" is lost, and certain signals appear in terms of mouthfeel and taste:
A bitter mouth suggests liver heat or gallbladder disease; a sweet mouth suggests spleen heat; a salty mouth often indicates kidney deficiency, due to the upward flow of kidney fluids; a sour mouth is a sign of rising liver qi, often suggesting liver deficiency; and a fishy mouth is a precursor to lung heat. A sudden loss of taste in the elderly is often a sign of a cerebral infarction. For a long-term bedridden patient who has had no appetite for a long time, a sudden craving for a specific food might be a sign of a "last gasp of life." I remember when I was a medical student on a hospital internship a long time ago, an elderly lady who had been ill for a long time asked me for a meat ration, saying she wanted to eat braised pork. I gave the ration to her daughter. Afterwards, the lady had a few bites of pork and quietly passed away the next day.