A few days before the procedure, limit fiber intake. The 24 hours before a colonoscopy, no solid food should be ingested, as recommended by Harvard Health. Only liquids such as clear broth, tea, coffee and Popsicles should be consumed. Do not eat or drink anything two hours before the procedure.
In addition to fasting, a colonoscopy requires the consumption of a "bowel prep" liquid provided by the doctor. This liquid fully cleans out the colon in preparation for the procedure. This is a necessary step because any obstructions in the colon make it difficult to see and evaluate potential polyps. Not adhering to the guidelines may result in a rescheduled colonoscopy, according to Harvard Health.