Misty (Indiana, US) on 11/01/2014:
We store glycogen and fat as energy specifically to survive periods of fasting. Using stored energy allows the body to take a break from digestion and really focus on healing the body. Longer fasts (generally 10-40 days) can even cure chronic disorders such as allergies, asthma, IBS, diabetes, etc. There are cases of obese patients water fasting for 90 days or more (under doctor's supervision of course) and keeping the weight off indefinitely.
A simple cold, sinus infection, or flu, however, can be rid from the body by fasting for several days. Water fasting is generally most effective, but bone broth, vegetable juices in moderation, and small amounts of coconut oil may be taken if going without food is too uncomfortable. Fruit juices are discouraged because the sugar can encourage bad bacterial growth. Fasting will also discourage lingering mucus and other cold symptoms after it's run its course.