The immediate results of a fast differ, depending on how toxic one is. If very toxic the fast can stir up a lot of crap ~temporarily~ that the candida can thrive off. This is where enemas or Epsom Salts can aid in releasing the toxins.
Regardless the long term effect of the fast will be cleaning you out, and weakening the candida while strengthening the immune system. If very toxic dont try fasting for more than a day or two at first.
Natural sugars (fruits) will start to not be a problem for you as you get cleaner. But dont ever binge on sugars after a fast, when trying to balance candida. The key is very gradual dietary changes. Fresh veggies or for some a veggie broth (which will have more concentrated sugars) is the ideal way to end a fast.