I've read a few people drink a tea laxitive the night before in order to go in the morning. Salt water is still recommended in this case cause it kinda acts like 'drano' going through your system.
1) There's a lot of water that is pipe cleaning your insdies
2) The 'salt' in the saltwater acts as an abrasive to help things break down (think of it like liquid sandpaper)
And the salt water is something 'indigestible' by your body, that's why it goes straight down the #2 track - because on your all liquid diet, the lemonade doesn't take that route.
