The causes of weak body and weak legs are related to physiological factors, low blood pressure, low blood sugar, anemia, cold and fever. 1. Physiological factors: the occurrence of weak body and weak legs cannot be ruled out due to overwork factors, such as after heavy physical labor, may be due to excessive physical exertion, which leads to the above symptoms. 2. Low blood pressure: For patients with blood pressure below normal level, it may be due to postural hypotension, low blood pressure during pregnancy or postprandial hypotension, etc., which may produce the symptoms of lack of energy and weak legs, accompanied by dizziness and nausea, and blurred vision. 3. Hypoglycemia: If the level of glucose in the plasma of the patient falls below the normal value, it will produce symptoms of palpitation, hunger, sweating, and accompanied by lack of energy and weakness of the legs. 4. Anemia: If there are not enough red blood cells in the peripheral blood of the human body, it cannot supply blood and oxygen to the tissues and organs, which will easily cause the patient to have symptoms such as weak body, weak legs and pale face. 5. Cold and fever: If the patient’s immunity is low, coupled with not pay attention to warmth, cold and flu, it is easy to cause fever, because of viral and bacterial infections, resulting in a buildup of metabolic products in the patient’s body, which can not be discharged from the body, and then produce a lack of energy, leg weakness and generalized aches and pains. It is recommended that the patient can go to the hospital, need to cooperate with the doctor to improve the relevant examination, to understand the specific causes before treatment, not blindly use drugs.