Patients preparing for a colonoscopy should eat a low-fiber diet starting three days before the procedure and stop solid foods the day before, according to Harvard Medical School. The patient follows a clear-liquid diet once she stops eating solids.
The low-fiber diet in the days leading up to the colonoscopy means no whole grains, legumes, fresh or dried fruit, raw vegetables, nuts and seeds. Foods that are acceptable on the precolonoscopy diet include dairy products, meat, smooth peanut butter, almond butter and oils. Also acceptable are strained soup that doesn't contain restricted ingredients, white rice, breads made from refined white flour and cooked vegetables and fruits without the skins, as described by Group Health Cooperative.
The clear-liquid diet the day before eliminates all solid foods. Acceptable foods include clear broth, tea, black coffee, clear fruit juice and clear sports drinks, according to Harvard Medical School. Red liquids should be avoided, as they may look like blood during the procedure, as explained by the Mayo Clinic. No food or drink of any kind are allowed in the two hours before the surgery.
The doctor may prescribe a drink designed to clear the bowels the night before the colonoscopy. The doctor provides specifics on dosing and timing of the liquid, says Mayo Clinic.