Colonoscopy prep is hard enough as it is. Consume a bunch of laxatives and then poop pure liquid for hours. But then you also have to follow the colonoscopy prep diet! Clear liquids aren’t exactly the most filling of foods.
I’m here to help. This extensive guide to the colonoscopy prep diet will help you think more creatively about your food options! And I might just provide a few controversial questions for you to ask your gastroenterologist…
It turns out, there is some research to suggest you don’t need to follow a clear-liquid diet for the entire day before your colonoscopy.
Just a reminder that I’m not a doctor or a nurse or any sort of medical practitioner. I’m just a patient with Crohn’s Disease who has a lot of firsthand experience with colonoscopies. And I enjoy researching things on the Internet. I write these posts about colonoscopies to help people who might otherwise be intimidated.
Note: This post contains affiliate links.
Two Stages of the Colonoscopy Prep Diet
Preparing for your colonoscopy should begin sooner than the day before your procedure. Ideally, you alter your diet two days before your procedure. You adjust your diet again the day before your procedure, and you stop consuming anything (including clear liquids) two hours before your colonoscopy.
Following a Low-Residue Diet
What is a low-residue diet?
Basically, you only eat foods that digest easily. You want to avoid leaving any “residue” in your digestive track, which could interfere with your colonoscopy. I actually follow a variation on this diet all the time to avoid aggravating my stricture (a narrowed section of my small intestine).
A typical healthy diet includes plenty of insoluble fiber, but a low-residue diet avoids insoluble fiber. Consider this your chance to enjoy white bread and white rice!
This is not an exhaustive list of low-residue foods, but since you only need to follow this diet for a day or two, you should find plenty to eat!
- Refined or enriched grains, like white bread, white rice, and white pasta. You’re looking for a soft and smooth texture. No whole grains or seeds or anything rough.
- Cooked cereals like cream of rice, cream of wheat, and grits. No oatmeal.
- Cold cereal IF it has 1g or less of fiber per serving.
- Bananas. Soft cantaloupe and honeydew melon.
- Lean meats. Fat and gristle aren’t fiber, but they don’t digest easily, so you want to avoid those.
- Dairy products if tolerated.
When to Start a Low-Residue Diet
You should begin following a low-residue diet at least two days before your colonoscopy. If you’re nervous about thoroughly cleansing your colon, you might want to start a low-residue diet a few days in advance of your colonoscopy.
Following a Clear-Liquid Diet
What is a clear-liquid diet?
Clear liquids refer to liquids that you can see through. More or less. If you pour a clear liquid into a clear glass, you should be able to see through it, at least a little bit.
Clear liquids before a colonoscopy are even more restricted. You need to avoid red, blue, and purple colors. These can interfere with your colonoscopy.
Allowed Clear Liquids
Again, this is not an exhaustive list of clear liquids. Just a few ideas to survive your colonoscopy prep diet! Remember to avoid red, purple, and blue versions of these clear liquids.
- Apple juice, white grape juice.
- Plain gelatin (no fruit or marshmallows added).
- Clear broth.
- Tea, coffee (no milk or creamer added).
- Sports drinks. You should drink a fair amount of these anyway to stay hydrated.
When to Start a Clear-Liquid Diet
Generally, you begin following a clear-liquid diet the day before your colonoscopy. I actually like to start a little bit earlier, with dinner two nights before my colonoscopy. I’ve found that my prep is more comfortable when I start clear liquids just a little before schedule. However, this is totally optional. In fact, you should ask your doctor about a more flexible colonoscopy prep diet.
An Alternative Colonoscopy Prep Diet
I’ve always followed a colonoscopy prep diet that erred on the side of caution. In fact, for my first colonoscopy, I misread the instructions and followed a strict diet of clear liquids only for three full days! I do not recommend this strategy!
Low-Residue Diet vs. Clear Liquid Diet
Does just the idea of an entire day of clear liquids make your stomach growl in hunger? I have good news for you!
Some gastroenterologists are changing their recommendation for their patients’ colonoscopy prep diet. It’s possible that the day before your colonoscopy, instead of consuming clear liquids all day, you can enjoy low-residue foods for breakfast and for lunch.
Multiple studies have compared patients who followed the traditional clear-liquids diet with patients who followed a low-residue diet. Overall, both sets of patients had adequately clear bowels. However, patients who were able to eat low-residue foods were happier! (In non-clinical terms, at least).
This interview with a researcher shares some of the positive outcomes for patients who follow a low-residue diet the day before a colonoscopy.
Because I don’t have full access to the studies or the meta-analysis of the studies, I can’t definitively say what all the low-residue diet plans entailed.
One gastroenterologist actually shared his firsthand experiences with his own colonoscopy–and his decision to follow a low-residue diet, against his doctor’s orders!
Red Juices vs. Red Dyes
I’ve done some research on the recommendation to avoid red, purple, and blue clear liquids. It seems like the problem has more to do with artificial food coloring. Red, purple, and blue liquids most likely have red dyes in them.
But what about natural fruit juices that are red in color?
So… drinking natural fruit juices with no artificial colors might be okay.
Talk to Your Doctor About Your Colonoscopy Prep Diet
If you want more flexibility in your colonoscopy prep diet, talk to your doctor! Your gastroenterologist might approve a low-residue meal or two the day before your colonoscopy. They also might approve natural fruit juices, even if they are red or purple in color. These small changes can make a big difference in your hunger levels the day before your colonoscopy.
How to Avoid Hunger with Clear Liquids
So you talked to your doctor, and they still want you to follow a clear-liquid diet. Or you just found this blog post the day before your colonoscopy, and it’s too late to ask your doctor about a low-residue diet.
Don’t worry, you won’t starve on a clear-liquid diet! It’s all a matter of drinking enough clear liquids, and drinking the right clear liquids.
First of all, you really do need to drink consistently throughout the day. Water, juice, tea, whatever–you need to keep drinking all day long. Your colonoscopy prep can dehydrate you, so you want to get plenty of liquids and nutrients in your body before it all rushes out your butt.
(I won’t apologize for being graphic in a blog post about colonoscopies).
In addition to drinking often, you need to consume nourishing clear liquids. Homemade gelatinous treats and homemade bone broth are your best options. (Just strain your bone broth through a coffee filter to clear out any herbs or sediment).
Amazon sells plenty of plain gelatin so you can make your own flavored jellos at home. You can also buy it in grocery stores. I think I have the Kroger brand of Knox gelatin packets. Follow the recipe instructions with your favorite fruit juice, soda, or sparkling water for a satisfying snack during your colonoscopy prep diet.
Amazon also sells plenty of broth options if you don’t have time to make your own. I recommend choosing a low-sodium one because your colonoscopy prep will be high in sodium. You can also buy it in grocery stores.
Finally, I have one last little tip. Even if you’re following a clear-liquid diet the day before your colonoscopy, you can have one last low-residue breakfast… IF you wake up early enough!
You need to finish this meal a full 24 hours (26 hours is better) prior to your scheduled procedure time. So if your colonoscopy is at 9am on Tuesday, then you can eat a big low-residue breakfast from 6:30-7am on Monday morning.
Starting your day with some eggs and some plain yogurt will make your clear-liquid diet so much easier.
Colonoscopy Prep Diet FAQs
Now that I’ve given all the general advice I can on following a colonoscopy prep diet without starving, let’s answer some FAQs! These all came from Google, so I know real people have these colonoscopy prep diet questions.
Can I eat chocolate before a colonoscopy?
Maybe! If your doctor approves you for a low-residue diet, you can eat some forms of chocolate before a colonoscopy. Just avoid any chocolate with nuts! Nuts are very much HIGH residue.
What is clear soup for a colonoscopy?
Beef broth, chicken broth, vegetable broth, and fat-free consomme are all clear soups for a colonoscopy. Just be sure you’re only eating the broth and not any meat or vegetables.
Are gummy bears a clear liquid?
Yes! For the purpose of your colonoscopy prep diet, gummy bears are a clear liquid. Just avoid the red ones.
What if I accidentally drank milk before my colonoscopy?
Proceed anyway. Before my first colonoscopy, I had some butterscotch candies, not knowing they had milk in them. My bowel prep was still adequate. Keep focusing on drinking clear liquids and finishing ALL of your colonoscopy prep. Then a little bit of milk probably won’t make a difference.
Can I drink alcohol before a colonoscopy? Can I drink alcohol after a colonoscopy?
You really shouldn’t drink alcohol before or after a colonoscopy.
Even though it’s technically a clear liquid, alcohol is dehydrating. You will already be at risk for dehydration from the colonoscopy. If you underwent any sedation, as most people do for a colonoscopy, that can mix dangerously with alcohol.
It’s better to just skip drinking alcohol for several days around your colonoscopy.
Extra Colonoscopy Prep Tips
If I didn’t answer all of your questions about colonoscopy prep, check out my other posts!
- What Your Doctor Won’t Tell You About Colonoscopy Prep
- “How Long Do You Poop After Colonoscopy Prep?” (And Other Questions)
I’ve also put together a handy colonoscopy checklist to help you out during the full week leading up to your colonoscopy.
Thanks for reading! Happy pooping!