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What Is Clear Liquid Diet?

Medically Reviewed by Jabeen Begum, MD on September 30, 2022

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What Is a Clear Liquid Diet?

This is a diet made entirely of liquids that are transparent at room temperature. The liquids may have color but must be transparent. This rules out liquids such as milk and orange juice. 

Clear liquids contain mainly carbohydrates and are the easiest for your digestive system to break down. The protein and fat content of such diets is low.

A clear liquid diet reduces stimulation of the stomach and intestines and provides rest to the digestive system. This is helpful if you are recovering from a digestive disease.

One such disease, colorectal cancer, is one of the most common cancers in adults. Your doctor will perform a colonoscopy to diagnose it. This procedure consists of passing a rigid or flexible tube with a light on the end into your colon. Having a bowel clear of undigested food and fecal matter is crucial to a successful colonoscopy, so your doctor may prescribe a clear liquid diet for a few days before a planned colonoscopy.

Your doctor may also prescribe a clear liquid diet before planned abdominal surgery. Vomiting is common during general anesthesia, and the vomited material may enter your airway, causing you to choke. A clear liquid diet before surgery reduces the risk. 

A fully liquid diet is different from a clear liquid diet. It is a step between prolonged fasting because of illness or surgery and a return to normal meals. A fully liquid diet has no restrictions on the type of liquids consumed. It has no purpose to fulfill beyond getting a patient used to intaking nutrition by mouth again. As soon as possible, a person on a fully liquid diet will be allowed to consume semi-solids in preparation for their regular food. 

Purpose of a Clear Liquid Diet

A clear liquid diet is not something you should do on your own. It has no health benefits when you are well. Your doctor will prescribe this diet under definite circumstances to provide clear liquid diet benefits, such as:

  • Before a medical test such as an endoscopy. The lack of residue associated with this diet allows an unhampered view and allows your doctor to make a diagnosis.
  • Before a planned surgery on your bowels
  • In cases of uncontrollable nausea, vomiting, or diarrhea
  • In cases of acute pancreatitis, a dangerous inflammation of the pancreas
  • After abdominal surgery, in order to minimize stomach stimulation and nausea. It is only needed for a day or two, and your doctor will soon switch you to more substantive meals.
  • In cases of diverticulosis to reduce fecal mass in the colon

A clear liquid diet is prescribed for stomach or intestinal disorders. Such a diet avoids the strain of digestion while providing some energy, nutrients, and liquids. It allows the bowels to rest and heal.

Clear Liquid Diet Foods

What can you have on a clear liquid diet? 

You must try to meet your fluid and energy requirements while keeping to the requirements prescribed based on your condition or upcoming procedure. Some permitted liquids include:

  • Water
  • Ice
  • Some clear fruit juices without pulp
  • Energy and sports drinks
  • Carbonated drinks
  • Clear broth
  • Gelatin (Jell-O)
  • Coffee with no milk or cream
  • Tea with no milk or cream

As an example, grape juice is permitted because it is transparent, though pigmented. Prior to a colonoscopy, though, your doctor may advise you not to have any drinks with a red or purple color. Their residue looks like blood and can make things difficult for your doctor.

Depending on your clinical condition, your doctor may also allow you honey and hard candies.

You can't eat solids when advised to maintain a clear liquid diet, with the exception of those like Jell-O that melt to liquid at room temperature.

How to Do a Clear Liquid Diet

Your doctor will give you detailed instructions when advising the clear liquid diet. Make sure you understand these instructions because it is essential to follow them precisely. You should write down the list of permitted liquids. Include a few of them for each meal. If you are at home, you shouldn't be on this diet for more than 5 days.

Remember to add up the liquids you're consuming in a 24-hour period. Normally, the water in your food meets much of your fluid requirements. When you are on a clear liquid diet, though, meeting your fluid requirement is especially important. Watch out for dark yellow urine and infrequent urination — these are signs of dehydration.

If you have diabetes, let the gastroenterologist who prescribes the clear liquid diet know. They may involve a dietician in your care. You should have 200 grams of carbohydrates during a day, spread out throughout the day, to keep your blood glucose levels controlled. You should monitor your blood sugar level frequently. Your doctor may want to switch you to your regular meal plan sooner if you have diabetes.

Clear Liquid Diet Nutrition

Nutrition is challenging when you are on a clear liquid diet. It isn't possible to meet your calorie, protein, and other nutrient requirements while on such a diet, which is why you're not advised to follow it for more than five days. In a hospital, your doctor will prescribe parenteral nutrition if the clear liquid diet is needed for a prolonged time. At home, they may prescribe high-protein gelatin or other low-residue supplements to meet your protein and energy needs.

Problems With Clear Liquid Diet

This is an extremely restrictive diet with poor nutritional balance and content. About 29% of people can't tolerate being on a clear liquid diet, as this diet has several adverse effects in addition to long-term nutritional deficiencies, including:

  • Hunger
  • Nausea
  • Vomiting
  • Abdominal discomfort or pain

The clear liquid diet is not meant for weight loss. It's not a wellness measure, either, since it is low in protein, energy, and other essential nutrients. The clear liquid diet is simply a short-term measure to be taken under medical supervision in certain situations. 

Show Sources

SOURCES:
Gastroenterology Nursing: "A Systematic Review and Meta-Analysis of Low-Residue Diet Versus Clear Liquid Diet: Which Is Better for Bowel Preparation Before Colonoscopy?"
Mayo Clinic: "Clear liquid diet." 
Oates, J., Sharma, S. StatPearls, "Clear Liquid Diet," StatPearls Publishing, 2022.
Range, T., Samra, N. StatPearls, "Full Liquid Diet," StatPearls Publishing, 2022.
Stanford Medicine: "Clear Liquid Diet Guidelines."

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