Juicing isn't fasting, actually juicing is getting more easily absorbable nutrition...read Max Gerson on why this is a good thing.
Fasting as in starving, can help the liver if done till noon. But this is nothing that can't be fixed much better with chelation, niacinamide and SCD...and for most people, those without the instestinal damage its simply <72g of carbs not even SCD...