juice fasting AND water fasting?

im trying to lose a substancial amount of weight in the next sixty days and i was wondering what would work better- straight up juice fasting or alternating juice fasting days and Water Fasting days? i will be exercising; walking 3 hours a day 3-4 days out of the week and the other days, i work at mcdonalds for 8 hours at a time. to lose 70 lbs in the shortest amount of time, which route should i take? :)