You don't want to have a full stomach when you work out
The foods you eat before you exercise and the timing of your meals or snacks really does matter. You don't want to have a full stomach when you work out, but you don't want to be hungry either. If you eat a large meal just before you exercise, you may experience nausea, feel sluggish or end up with muscle cramps. This happens because your body needs energy to digest the foods you eat so blood flow increases to your digestive system, leaving less energy-providing blood for muscles.