you'd think that would be an easy question to answer. but its really quite strange.
When I was juicing "seriously" I would make 64 oz of veggie juice (with an apple or two to keep it palatable) and drinking 16 oz for breakfast, and filling 3-16 oz thermoses to take to work and drink throughout the day. This strategy works well if you are committed. But if I decided to go out to lunch with the normal lunch group at work, I could eat a full lunch and drink all of the juices (which is not a good weight loss strategy). I was loosing weight when it was juice all day except for dinner, but only when the shakes were mostly veggies (instead of fruit).
I find that shakes fill you up more than juice (the pulp makes it take longer to digest). So a Vitamix is a better investment than an expensive pressure juicer. It is also useful for more things.
anyway, now I do a 24oz spinnach+carrot+fruit+yogourt shake at night before bed, and eat normally for my 3 other meals. I'm not loosing weight, but I feel great.