Colonoscopy Diet: What to Eat and Avoid Before Your Procedure

When you’re preparing for a colonoscopy, a medical procedure to examine the inside of your colon using a flexible camera. It’s not just about showing up—you need to follow a specific colonoscopy diet, a set of eating rules designed to clear your digestive tract in the days leading up to it. This isn’t a suggestion. If your colon isn’t clean, the doctor can’t see polyps or other issues, and you might have to reschedule the whole thing.

The colonoscopy diet, a set of eating rules designed to clear your digestive tract usually starts 2–3 days before the procedure. During this time, you switch from regular meals to low-residue foods, easily digestible items that leave little waste in the intestines. Think white bread, plain rice, eggs, skinless chicken, and cooked vegetables without seeds or skins. You avoid fiber—no whole grains, nuts, raw veggies, or fruit with seeds. Even tomato skins and berries are out. Why? Because fiber doesn’t break down easily and can stick to the colon walls, hiding small growths.

Then, the day before your colonoscopy, you move to a clear liquid diet, a regimen of transparent fluids that leave no residue in the gut. This includes water, clear broth, apple juice, ginger ale, black coffee (no cream), and sports drinks without red or purple dye. Jell-O is okay if it’s yellow or clear. Anything opaque or colored like red, purple, or blue is banned—those colors can look like blood during the exam. You also stop eating solid food entirely. No chewing gum, no candy, no ice chips with pulp. The goal is to flush everything out so the colon is as empty as possible when the scope goes in.

Timing matters too. Most people start their clear liquid diet the day before, but your doctor will give you exact instructions. Some may ask you to begin earlier if you have slow digestion. You’ll also get a bowel prep solution—usually a strong laxative—to drink the night before or the morning of the procedure. This is what actually cleans you out. But if you didn’t follow the diet, that laxative won’t work as well. You might end up with cloudy fluid in your colon, and the doctor might miss something important.

People often ask: Can I drink alcohol? No. Can I have tea? Only if it’s clear and doesn’t have milk or honey. What about protein shakes? Only if they’re labeled clear and don’t contain pulp or thickening agents. And don’t forget: even a single bite of a sandwich the day before can mess things up. This isn’t about being hungry—it’s about safety and accuracy. A clean colon means fewer missed diagnoses and a faster, smoother procedure.

After the colonoscopy, you’ll go back to normal eating, but your doctor might suggest easing back in with light meals. You might feel bloated or gassy from the air used during the exam, so avoid carbonated drinks and heavy foods at first. Most people feel fine within a few hours.

Below, you’ll find real advice from people who’ve been through this—what worked, what didn’t, and how to avoid common mistakes. Whether you’re doing this for the first time or you’ve had it before, there’s something here to help you get it right.