Protein Supplement VS. Meal replacement

Glad to help. I personally found the bgs_final doc pretty informative although a hard slog to get through. I sometimes use the information when I am trying to educate my NUT about some of the differences ( my NUT might say argue but I prefer to think of it as continuing education ). 

I think you are worrying about the wrong thing.  There is a difference between protein supplement and meal replacement.  A protein supplement is just that.  Meant to be ingested in addition to a regular diet.  Meal replacement actually replaces food.  They have salts/electrolytes necessary to sustain life in addition to protein.  If you are just drinking shakes, you need to make sure they are meal replacement quality or you need to make sure you are getting the salts/electrolytes you need from other sources.  Just for example, something like gatorade.  And there are low carb meal replacement shakes out there.

The 25 to 30gr protein is mythology that has been repeated so many times it's just accepted by many as truth.  No one has proved this to be true.  Don't worry about 'wasting' protein.  Just worry about getting in enough.  And staying hydrated is much more important than the protein.  It will take you a while to get the hang of this!