V8 was suggested by Dr. A, I think, because many people are used to having juice as part of breakfast. It's a juice substitute, but NOT a veggie substitute. It's better for you than juiced fruit because it doesn't have the same amount of sugar, but the same rules apply for juiced veggies as juiced fruit...lots of calories for very little fiber.
You want to be eating more whole veggies so they fill you up and give you fiber. Drinking V8 won't hurt you, but it won't help you, either. When people on the boards say that the more veggies they eat, the more they lose, they aren't kidding. But they aren't talking about V8 either.
My nutritionist said that unless I was craving juice, to stop drinking the V8 and eat veggies instead. So now I have a cup of tomatoes with my cottage cheese or a bell pepper with hummus with my tomato basil burger in the morning.
If you have V8 for snack, make sure you include some protein, like nuts, beans, or cheese, or even a piece of lunch meat. V8 alone won't fill you up enough to carry you to the next meal.
Just my thoughts.