The idea of a liquid breakfast makes me go "ewwwwwww!"
I hate slim fast shakes - they taste like chalk. Carnation instant breakfast isn't any better. The taste disgusts me and makes me gag.
I could never do both liquid breakfast AND liquid lunch. I'd feel like an old person who can no longer digest anything
I'm not sure that liquid meals really do assist in weight loss progression, either, because if you get TOO few calories, your metabolism slows down. Eating liquid breakfast and lunch would either mean depriving your body of the calories that it needs or eating a JINORMOUS dinner.
A liquid breakfast, nutritionally speaking, is fine and possibly a good idea if you're into that kind of thing, but
in my opinion, anything more than that is just a liquid diet setting you up for failure because most people can't stick to it or maintain it for life.