No energy, weak legs, panic cause of hypoglycemia, potassium ion deficiency, etc., as follows:1, hypoglycemia: when hypoglycemia, it will cause no energy and obvious panic, in addition to these symptoms, the patient may also appear sweating, and may cause dizziness in severe cases, or even mental disorders; 2, potassium ion deficiency: potassium ions are the most important trace elements, when potassium ion content is low, it will cause rapid heart rate, causing muscle cells in the limbs to contract and have no energy, thus resulting in the feeling of weak legs; 3, other: there may be severe heart failure or anemia, which may cause weak legs; 3, other: there may be severe heart failure or anemia, which may cause weak legs. When the potassium ion content is low, it will cause fast heart rate, cause the muscle cells of the limbs to contract and have no strength, thus appearing the feeling of weak legs; 3, other: there may be serious heart failure or anemia, which can cause weak body, weak legs and panic.