If a patient eats right before a colonoscopy, liquid or food could move into the esophagus, and the patient could breathe it into his lungs, according to the Colon Prep Center. When a patient disregards the doctor's preparation instructions, the doctor reschedules the procedure.
Physicians administer sedatives to their patients to relieve tension and anxiety during the diagnostic procedure, explains the Colon Prep Center. The drugs prevent the stomach from holding food or drink as it would normally. Patients who eat before undergoing a colonoscopy and do not inform their doctors create a health and safety risk and endanger their lives if they go forward with the procedure.