I was sick on tuesday morning and so I started fasting. No food only juice and water. by thursday i felt pretty good and by thursday evening I felt great. i had plenty of energy and the cold was gone. I did yoga on thursday evening and went way deeper in the poses then ever before. If you get sick and loose your appetite, your body might be saying it wants a fast too. It gives some of your organs a break from working so hard and that allows the other organs to work hard on cleansing out the toxins that have built up. you might have a fun experience in the process. Yoga, what a ride 
PS
my vanity was happy cause I also lost ten pounds in those four days 