There are several possible reasons for the lack of energy in the eighty-year-old elderly: First, to exclude tumors, a common feature of tumors of parenchymal organs is progressive weight loss. Tumors in different parts of the body show different symptoms. Tumors of the digestive system will show difficulty in eating if they are in the esophagus and stomach, and may show symptoms of bloating and abdominal pain if they are now in the liver, gallbladder and pancreas. If it occurs in the intestinal tract, constipation and blood in stool may occur. Second, the elderly must look for anemia if they have no energy. Older adults may have iron deficiency and/or bi-directional anemia due to poor teeth, picky eating or partial eating. Just peel back the eyelids and see if there is any obvious pallor in the eyelids or pallor in the mouth and lips, basically you can tell. Third, the elderly must look for chronic renal insufficiency. Chronic renal insufficiency can appear anemia, but also can appear renal face, renal face is obscure, no light, but a little grayish black color. Fourth, endocrine system diseases. If the elderly have some chronic diseases that are not well controlled, such as hypertonicity or recurrent hypoglycemia caused by uncontrolled blood sugar, they can have a general weakness. The main manifestation of hyperthyroidism is generalized weakness, emaciation and anorexia. Fifth, cardiovascular disease. Some patients, especially those with cardiac insufficiency, mainly show weakness, reluctance to move, chest tightness, palpitations and shortness of breath when they move. Sixth, there may also be lung disease. Long-term limitation of pulmonary ventilation, insufficient oxygen supply, and low oxygen saturation cause generalized weakness, and patients are characterized by cyanosis of the face and dry lips. Seventh, some patients may be normal after the examination, but there is a state of anxiety and depression that causes generalized weakness, which may be related to the depressed mood of the elderly. In conclusion, if the elderly have a generalized weakness and it is obvious, family members should pay high attention to it. First of all, we should check the blood count to determine whether there is anemia. In addition, it is important to check blood sugar, kidney function and ions. Patients with low potassium may also experience general weakness.