In this era of “thin is beautiful”, many women are not generally happy to see the gradually smaller number on the scale. However, for normal people, no change in diet, exercise, sudden weight loss in a short period of time, this is not something to be happy about, it is likely to be an early “signal” of disease. The following is a brief overview of several diseases that can lead to sudden weight loss, we should be alert to ah. 1, malignant tumors, particularly alert to colon cancer, pancreatic cancer. Since the growth of tumor will compete with the body for nutrition, most of the malignant tumors will first appear the symptoms of losing weight. For example, pancreatic cancer, which is often mistaken for stomach disease, has the prominent symptom of significant weight loss, and can even lose more than 10 kg in a month. As for colorectal cancer, which has no obvious symptoms in early stage, patients may only feel discomfort, indigestion and weight loss, and do not realize that it is a malignant tumor, so people over 50 years old should be especially alert to this. The department of gastrointestinal surgery and oncology are the most important departments for consultation. Hyperthyroidism in young adults is easy to identify. Suddenly eating more and losing weight, and having symptoms such as protruding eyes, palpitations and sweating, it is likely to be a problem of thyroid gland. However, elderly patients are not so easy to identify, they may not eat too much, and they do not have “big neck” or “protruding eyes”, but their weight is getting lighter and thinner. 3. Diabetes, especially in patients who are thin and have “three more”. “As the diabetic patients do not have enough insulin in their bodies, they cannot make full use of the glucose in the blood, so when their bodies need energy, they can only consume fat and suddenly lose weight. Patients with these conditions can be seen by the endocrinology department. 4, chronic infectious diseases such as tuberculosis, chronic liver disease, etc. Cirrhosis, liver ascites and other liver diseases will affect the body anabolic metabolism down, consumption metabolism up, people will also lose weight within a few days, especially cirrhosis in weight loss, but also accompanied by weakness, diarrhea and other symptoms. Such patients can go to the gastroenterology and hepatology departments, while tuberculosis bacteria mainly invade the lungs, tuberculosis can go to the respiratory and tuberculosis departments. 5, chronic gastritis, peptic ulcer, chronic non-specific colitis and other gastrointestinal diseases Gastrointestinal system diseases can cause patients with food digestion and absorption, utilization disorders, resulting in poor digestion and absorption function, patients with wasting, loss of appetite and other problems, should promptly go to the Department of Gastroenterology for consultation. 6, hypoadrenocorticism Patients with chronic hypoadrenocorticism, with insidious onset in the early stage, may only appear some common chronic symptoms, such as weight loss, weakness, loss of appetite, etc. With the gradual aggravation of the disease may also appear general discomfort, listlessness, lethargy, dizziness and postural hypotension. Patients should go to the endocrinology department to check in time. 7, pharmacogenic wasting is often caused by taking some drugs that enhance human metabolism, such as dinitrophenol, thyroxine, etc.. Especially the elderly after taking these drugs, weight loss in a period of time persistent, should be vigilant and promptly seek advice from the prescribing doctor.