If your colonoscopy appointment is after 1 p.m. the next day, you are allowed to have a light breakfast before 9 a.m. the day prior (see the prep instructions on the SDG website). Otherwise, solid food the day before the procedure can cause the colonoscopy prep to be less effective, and we may not be able to see well enough to consider it an adequate exam. Most of the time, if you add 2-3 capful doses of Miralax or a bottle of magnesium citrate mid-day, and begin the prep that evening as instructed, this will be enough to still achieve a good prep for the exam. The goal is to have urine or tea-colored movements by the end of your prep, and often this can still be achieved.