As @stevemobster has already said it, we need to know more about your diet in order to give the best advice. But personally, I would not introduce fruit juice into a diet, as it will have tons of sugar, and I am talking about the natural juice here! With the whole fruits this carb intake is partially ok because you are also getting in a good deal of healthy fiber, but this is not the case with fruit juice, so better avoid it if you want to lose weight.