Nutrition is an important thing in regards to quality of life. With adequate nutrition your body will have the nutrients and vitamins that are vital in keeping the homeostasis of our bodies intact, and when this happens, you are feel good. However without adequate nutrition you are predisposed towards diseases that result directly from the lack of adequate nutrition (Like Bari-Bari if you lack Vitamin b12) or your body is inadequate when fighting illnesses like the flu because it doesn't have the energy and nutrition required to help fight.