The causes of weakness and lack of energy can range from physiologic factors to disease. Physiological factors to consider lactic acid accumulation, disease factors to consider chronic fatigue syndrome, diabetes, tuberculosis, anemia and so on. 1 Lactic acid buildup: After a lot of exercise, lactic acid buildup in the body will appear as a symptom of lack of energy and fatigue, accompanied by muscle aches and pains. Generally do not need treatment, a few days after the body of lactic acid will be metabolized, the symptoms will be relieved. 2. Chronic Fatigue Syndrome: It occurs in people who are under great pressure from study and work, and is a kind of sub-health state, which manifests itself in lack of energy, weakness of limbs, emotional changes, lack of concentration, etc. Through rest, psychological guidance, and Chinese medicine, the symptoms can be improved. 3. Diabetes: diabetes is often manifested in poor glycemic control as lack of energy, weakness of the limbs, accompanied by thirst, drinking and urinating, weight loss and other symptoms, after diet and exercise or medication to reduce sugar can be improved. 4. Tuberculosis: Mycobacterium tuberculosis infection is also prone to lack of energy, weakness of the limbs, accompanied by emaciation, night sweats, low-grade fever and other symptoms, and need to be actively anti-tuberculosis treatment. 5. Anemia: Anemia will also appear the clinical manifestations of lack of energy, weakness of the limbs, often accompanied by blepharoconjunctival pallor, dizziness, blackouts and other symptoms, if necessary, need to be under the guidance of the doctor blood transfusion or iron supplementation therapy. Therefore, there are many causes of fatigue and lack of energy, which need to be combined with the patient’s accompanying symptoms, under the guidance of the doctor, complete the relevant examinations to determine the cause.