It is best not to swim on an empty stomach, because swimming is a whole-body aerobic exercise, the exercise itself requires a lot of energy consumption, and because the water temperature is lower, the water thermal conductivity than air, the body to consume a lot of energy to maintain body temperature, the lack of energy sources when fasting, easy to produce hypoglycemia, dizziness, nausea, weakness and other symptoms, and even fainting in the pool choking events, life-threatening. It is also possible that hypothermia leads to cramps and cannot swim normally, leading to muscle damage or risk of accidents.