There are many reasons for the lack of energy in the body. First, if the thyroid gland is not secreting enough, it will easily cause weakness and fatigue in the body. Second, if there is anemia, it will cause the body’s hemoglobin to become low, which will also cause the body’s oxygen supply to be insufficient, causing the body to be weak. Third, if the eyes are usually too tired, it will also cause the body bones loose, limbs tired and weak. Fourth, if the usual caffeine intake is relatively large, often eat chocolate will also cause weakness. There are also many factors that can cause weakness, such as irregular sleep at night, or the usual lack of exercise, biological clock disorders, will feel weak, so when this happens, first to find the cause, and then conditioning and treatment.