That's a very different protocol than my clinic.  I had RNY on 1/19 and was on clear liquids until 1/23, when I started the Stage 1 bariatric diet, which is 2-3 protein shakes a day (25-30 g protein each) plus lots of clear liquids.  I started Stage 2 yesterday, which is 2 protein shakes a day plus 2-3 very small meals of pureed foods.  We're supposed to get 60-70 g of protein a day.  The nutritionist said that since we're eating so little right now, we need to get most of our protein from the shakes.  The pureed food doesn't have to be high protein (applesauce is fine) but it can't be high carb.  I'll move to stage 3 (regular food) in about 2 weeks.

Your body really needs protein to heal well, so I'm surprised they'd have you drink Carnation Instant Breakfast, which I think only has about 5 g per shake.  It wouldn't hurt to invest in some protein powder and have a high protein shake every day.  There are varieties that have very low (even zero) carbs and that are sugar free.  I use Nectar, which I bought at a specialty nutrition store, but you can get it at Walmart too.

Hope that helps!
Barbara