Your body needs food as an energy source. The brain needs approximately 900 carbohydrate calories a day to function properly. When deprived of these calories the brain does not function as efficiently and slows down. You feel lethargic, can't concentrate or focus your attention and sometimes people feel depressed because of it.

Fortunately you can rebound quickly by eating some carbohydrates like a piece of fruit or a glass of juice.

The carbs are assimilated quickly and you will rebound and feel normal again.