The reason that fasting should be apart of your trainging program is: As you train you should train the entire person/body.  The order should be from the inside out.  The heart and the brain are a very important part of what you look like to others as well as how you do things including working out.  For example: The picture that you see of me I that in only 2 months.  I was 218lbs.  with a body fat of about 18%.  On this picture I am 185lbs. and a body fat content of about 6%.  This was accomplished by training from the inside out.  My goal was not to become cut or look good it was to train my heart and mind to be reflected in my outer appearance.  I accomplished this through prayer, reading a book(Renovation of the Heart) by DALLAS WILLARD, eating healthly foods, and while workingout uses that time as worship time. Before I knew it I was there.  My focus was not my looks but my heart and mind.