People often rely on smoothies and protein drinks for the period after surgery when on liquids and mushies. Once you are on solid foods, most (actually I think all) of the literature supporting the LAP-BAND
® and most of the medical professionals associated with the band do NOT recommend the regular consumption of smoothies and protein drinks. This has nothing to do with the merits or healthiness of the drink.
My understanding is that the meals you drink do not stay in your newly banded stomach pouch (they just slide on down), which can be a risk for weight gain as you may not feel full from a shake and may eat other solid food as well. In effect you can be doubling or tripling your calorie intake by drinking your calories, as well as eating, and now you have defeated the purpose of the band, which was to consume fewer calories. All the literature I have seen has recommended that the only "food" of caloric value that you should be drinking is milk.
The other purpose of the band is to "retrain" your eating patterns into eating habits that you can maintain for the rest of your life (portion control). To my mind that means eating real food (including the harder to eat meat and vegetables) that you will always be eating for ever.
Being banded shouldn't be about enduring or tolerating a diet for the time it takes you to lose weight, but a complete readjustment to lifestyle. Do you plan on getting much of your nutrition from shakes and smoothies for the rest of your life? If not, you probably don't want to get into the habit of relying on them.
Think about how Jenny Craig and other diets get you to eat their food. They work great as long as you eat their food, but you haven't actually made changes in your life to accommodate, so many (if not most) people put on the weight again once they start eating "regular" food, because they haven't learned to control portions and fat and calories themselves.
Just my 2 cents