Seika
You want to reduce bilis generation to a minimun and the vegetarian diet also helps clean your colon.
You do not want to be eating Animal Protein, icecream, fried food, and processed stuff.
But most importantly the day of and maybe the few days before you gotta be on a super clean diet.
All foods have protein, noone dies because of protein deficiency. You also do not need fat as long as you have
Sugar and this comes from the fruits, vegies and some carbs you may be eating.
You can start eating your fatty acids and some nuts and seeds after the flush, going a week without them is no big deal.
And yea lemon and other citrics promote bilis generation, reason I do not consume prior to the liver flush.