While fasting, you can only drink water or tea without sugar. Coffee with a small amount of milk (50-100 ml per day) is also fine. You can also drink vegetable juice and vegetable broth. After fasting hours, you can drink whatever you want, 5 days ago.
Taking a look at green juices that exclusively use vegetables and not fruits, 12 oz. They will contain at least 8 to 10 grams of carbohydrates. This carbohydrate level disrupts fasting and should therefore be used during the feeding window, not during the fasting period.