You probably have heard about the fight or flight response.

In an ideal situation when we are eating, the parasympathetic nervous system is dormant, so the digestive and lymph systems are fully activated. As we’re calmly chewing our food our stomach makes digestive juices that stimulate the intestinal tract and our lymph system can quickly deal with any viruses, yeast, fungi or bacteria.
If we sense some danger our body makes a shift in energy. Instead of focusing on proper digestion, our adrenaline levels go up and energy goes towards our skeletal muscles, ready for a fight or flight. As soon as the danger is no longer there the energy goes back to digesting our food.