The practice of fasting was instituted in order to revitalize our nature. Fasting is the hygiene of the soul, a cleansing. In the physical sense alone fasting Is good for you, and medically beneficial. Fasting gives us back our lost equilibrium and brings into harmony our mind, our soul and our body. Abstaining from excessive food results in the lightening of the capabilities of the mind and the soul.
Food is conducive to sleep rather than mental or physical activity.
Eating is the second most energy draining activity you can do. I believe fasting is understudied, because it is a powerful spiritual weapon. Satan seems to have done his homework in keeping believers from hearing these truths. However, the teaching of the New Testament assumes that fasting is already an important part of every believer's life. Apparently, Jesus did not consider fasting optional.