You can usually eat about 30~40 minutes after fasting exercise. It is usually not recommended to eat immediately after exercise, because just after exercise blood is still filled in the muscles, the blood supply of the gastrointestinal tract is relatively small, affecting the peristalsis of the gastrointestinal tract and digestive function, eating can not be effectively digested and absorbed, but also indigestion, belching (hiccups), bloating and other uncomfortable symptoms may occur. Before, during and after exercise can be moderate hydration. So after exercise it is generally recommended to eat after 30~40 minutes. At this time, the blood supply of the gastrointestinal tract increases, which is conducive to the digestion and absorption of food. If you exercise a lot and sweat a lot, you can extend the time according to the situation. Consult your doctor for more information.