The common people generally popular saying “money is hard to buy old age thin”, with this sentence describes people to the old age body thinner is expressed health, is a kind of evaluation of health. It means that the elderly can not be too fat, too fat will not live a long life. If the long-term intake of super-calorie diet will cause obesity. Older people’s activity is reduced, calorie consumption is also reduced, easy to get fat. Obesity often induces hypertension, hyperlipidemia, coronary heart disease, diabetes mellitus, and cerebral arteriosclerosis, etc., which brings great harm to health. Therefore, the prevention of obesity in old age is an important factor in safeguarding health. In this sense, “it is hard to buy old age thin” is right. But on the other hand, too thin is not good for health. Being too thin is a sign of malnutrition, lowered resistance and susceptibility to disease, so it should not be interpreted to mean that older people will be healthy as long as they are thin, nor should it be misconstrued to mean that the lighter they are, the better they will be. Especially in the short term weight loss should pay attention to potential diseases, because the elderly relatively slow reaction, many disease symptoms are not typical, but can be manifested as simple wasting, the following are common causes of wasting: 1, diabetes mellitus: a typical “three more and one less” performance that is, drinking, eating, urinating, wasting, but middle-aged and elderly people to Type 2 diabetes mellitus is more, some only have symptoms of wasting, or early asymptomatic only physical examination unintentionally found. 2, malignant tumors: the elderly is a high incidence of tumors, when there is weight loss accompanied by hemoptysis, black stools, change in stool properties, dysphagia, unexplained anemia, one of the systemic bone and joint pain, especially should be vigilant. 3, geriatric hyperthyroidism: the main manifestations of emaciation, palpitations, fatigue, dizziness, fainting, nervousness or apathy, diarrhea, anorexia, can be accompanied by atrial fibrillation, tremor and myopathy, 70% of the patients do not have goiter, easy to misdiagnosis and misdiagnosis. 4, tuberculosis and chronic infectious diseases: the incidence of tuberculosis in the last five years has been a rising trend, when there is a low fever in the afternoon, coughing, coughing up sputum, hemoptysis, emaciation, night sweats, chest pain symptoms, lasting more than two weeks, anti-inflammatory treatment is not good should be routinely take chest radiographs and sputum to find tuberculosis examination, so as not to delay the disease. Pay attention to potential chronic infectious diseases. 5, indigestion and malnutrition: the elderly gastritis, ulcer disease, cholelithiasis, chronic pancreatitis, inflammatory bowel disease can appear digestion and absorption disorders; there are also a few elderly people overly concerned about the health, health care products and medicines instead of a normal diet, resulting in malnutrition wasting. The word “thin” in the phrase “it is hard to buy thinness in old age” is, in my opinion, that the elderly should always maintain an ideal body weight, be energetic and have no chronic diseases, then such elderly people are healthy. The best way to maintain longevity is to take regular weight measurements and have annual health check-ups for early detection and treatment.