Uses and Benefits of a Clear Liquid Diet

Doctors usually ask patients to implement a clear liquid diet to sweep out any toxins and improve a diagnostical process. Today's article will discuss what people should keep in mind when undergoing this diet.
Uses and Benefits of a Clear Liquid Diet

Last update: 18 July, 2021

The clear liquid diet is an aggressive protocol people implement to cleanse their intestines. It isn’t recommended without the supervision of a professional and a specific objective. This is because it isn’t well-balanced and can lead to nutritional deficiencies if used over an extended period of time.

Doctors prescribe it for certain events, such as prior to an intestinal test. It allows the elimination of any waste lodged in the digestive tract and improves the diagnosis of underlying pathologies.

Continue reading to find out more about it.

The purpose of the clear liquid diet

The main objective of this diet is to sweep out any waste in the intestinal tract. It needs to be done for two reasons, cleansing the area or facilitating the diagnosis of disease with a subsequent test.

Either way, a person using it to improve bowel function or to cleanse impurities must do so carefully. As you’re about to see, this type of diet lacks many important nutrients. The body cannot function on it alone for an extended period of time.

A person eating soup.
The clear liquid diet is quite restrictive and people should only use it under medical supervision.

Characteristics of the clear liquid diet

This type of diet focuses on hydration, above all. It ensures water intake and electrolyte balance, considered key to health. Note that poor hydration can lead to blood pressure irregularities. Al least according to a study published in Nefrologia.

As we said above, this is a rather restrictive diet and a person can only eat the following:

  • Mineral, carbonated or flavored water
  • Strained fruit juices
  • Flavored drinks
  • Soft drinks
  • Tea or black coffee
  • Gelatin
  • Strained vegetable juices
  • Sports drinks
  • Skimmed and strained broth
  • Honey and sugar
  • Candy

The diet is often more restrictive though, it all depends on the specialist. Furthermore, it’s quite deficient when it comes to calories and proteins. Thus, a person mustn’t keep it up in the medium or long term.

You may already know that an adequate protein intake is key to prevent the development of chronic diseases. In fact, the requirements of these nutrients increased in dietary guidelines in recent years, according to a study published in the Annals of Nutrition & Metabolism.

Sample menu

There’s a wide variety of menus for this type of diet. The important thing is not to incorporate foods other than those recommended. In general, a doctor will determine the daily menu.


  • Black coffee with sugar
  • 1 fruit juice
  • Mid-morning
  • 1 c. of gelatin and a glass of juice


  • 1 glass of juice
  • Skimmed chicken broth
  • 1 c. of gelatin
  • Water


  • Black coffee with sugar


  • 1 c. of skimmed fish broth
  • 1 c. of gelatin
  • An infusion with sugar

When should a person follow this diet?

As we mentioned above, this isn’t a weight loss diet and people shouldn’t use it for long periods of time. It’s good for cleansing the colon before a colonoscopy or some other diagnostic test of the digestive tract.

Even, a person could use together with the appropriate supplementation in the case of marked bacterial dysbiosis. This is because it exerts a change on the microbiota before a person begins to gradually reintroduce fiber and solid foods to help the new bacteria settle.

A cup of broth.
A clear liquid diet is optimal before a colonoscopy or other diagnostic tests. It shouldn’t last too long as it lacks many essential nutrients.

Possible risks and contraindications of the clear liquid diet

As you can imagine, this diet won’t cover energy requirements. In fact, it doesn’t even meet the needs of essential macro and micronutrients. It’s simple, indeed, but there’s a risk of acute conditions due to an inefficient supply of nutrients if continued longer than necessary.

For example, a study published in the journal Advances in Food and Nutrition Research indicates that not consuming optimal amounts of vitamin C leads to scurvy in the short term. In turn, not meeting iron requirements leads to anemia.

Therefore, it’s only recommended to follow a dietary treatment of this type under medical prescription. This is why you must heed the advice of the professional on how to do so while minimizing the risks. They’ll probably instruct you to eat a certain amount of sugar to avoid hypoglycemia.

A clear liquid diet requires a strict protocol

In short, a clear liquid diet shouldn’t be used to lose weight. Neither is it advisable to do it at home to experiment with it. Its implementation can lead to harmful health effects, especially if not applied correctly.

It’s a short-term dietary method with a specific objective, and you shouldn’t use it beyond it. In addition, a health professional must supervise and endorse it to reduce the associated risks.

Finally, as a general rule, you should avoid excessively restrictive diets. This is because they don’t have any medium- to long-term health benefits and aren’t sustainable. The only thing you’ll get is disease conditioned by the inefficient supply of nutrients.

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  • Dizdar OS, Yeşiltepe A, Dondurmaci E, Ozkan E, Koç A, Gunal AI. Hydration status and blood pressure variability in primary hypertensive patients. Nefrologia. 2020 Sep-Oct;40(5):522-530. English, Spanish. doi: 10.1016/j.nefro.2020.02.002. Epub 2020 Jun 11. PMID: 32536454.
  • Richter M, Baerlocher K, Bauer JM, Elmadfa I, Heseker H, Leschik-Bonnet E, Stangl G, Volkert D, Stehle P; on behalf of the German Nutrition Society (DGE). Revised Reference Values for the Intake of Protein. Ann Nutr Metab. 2019;74(3):242-250. doi: 10.1159/000499374. Epub 2019 Mar 22. PMID: 30904906; PMCID: PMC6492513.
  • Granger M, Eck P. Dietary Vitamin C in Human Health. Adv Food Nutr Res. 2018;83:281-310. doi: 10.1016/bs.afnr.2017.11.006. Epub 2018 Feb 16. PMID: 29477224.