 [ Symptoms ] what is colorectal cancer [ Disease ] well i would suggest you simply eat a normal diet and follow the prep instructions to the letter fasting before a colonoscopy may sound like a good idea but could actually backfire abstaining from food or drink for 48 hours can have a profound effect on the digestive system and cause the prep solutions not to work correctly so again my advice is to follow the written instructions you received these instructions have helped thousands of patients achieve a good clean out prior to colonoscopy and with luck they will work for you too here is hoping things go better this time around