From your message, I tend to agree with AffectedMangoO that perhaps you should be considering a juice fast. It will provide you the nutrition you need to maintain your energy level.
To help your body rid itself of toxins during the fast, (water or juice), a Sea Salt enema every day is highly recommended. Enemas reduce the energy required for the body to eliminate toxins on it's own, leaving you with more energy to continue with your physical exercise during the fast.