Can I use the equate Walmart brand protein drinks for my pre-op diet?

My surgery date is June 26..

Can I also use them after surgery?

My nutritionist emphasized that the best was 100% Protein isolate, it's protein that is all available to the body. Isopure does (http://www.theisopurecompany.com) tells you where you can buy the Protein powder and maybe try them ahead of time.

I think I will get their ready-to-drink (RTD) high protein clear drinks for immediate post-op in case I can't tolerate the protein powders. I just bought a book called, "The Bariatric Foodie Guide to Perfect Protein Drinks." Some people buy unflavored and add the protein powder to not-too-hot Water or broth, or almond milk with fruit and/or Torani sugar free syrups or DaVinci zero calorie syrups (which Wal-Mart does have). If I have to do this, I'm making them as tasty as possible!

Has anyone used the Puritan whey Protein Isolate unflavored? The reviews are good but I don't know if I should invest for surgery. They told me yesterday not to use the Walmart Body Fortress whey protein-only isolate. No blends either.