If you have a bad taste in your mouth, fast for a meal, see if it clears it.
If you are constipated, fast until your digestive fire gets going.
If you feel stuck and heavy, fast for a day to lighten your spirits.
If you full of rich food, rich conversation, rich desires, rich media, fast for a day a week until you balance out the excess.
You'll find your own version of the above, or get help from a practitioner to do so, the point is to learn to have the habit of going without.
Our bodies are built to include a breaking system. Don't override it.