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As the name implies, a clear liquid diet consists only of clear or transparent liquids.
Your doctor may prescribe the diet as part of a treatment or as a preparation for some procedures.
This article explains everything you need to know about a clear liquid diet, including its purpose, what the diet allows, and whether it can help you lose weight.
A clear liquid diet consists only of clear liquids.
Your doctor may prescribe the diet if you are recovering from an episode of diverticulitis or pancreatitis (1).
In other instances, you may need to drink only clear liquids to prepare for a colonoscopy.
Diverticulitis and pancreatitis
Diverticulitis is the inflammation of small pouches called diverticula that can form along your large intestine.
Pancreatitis is the inflammation of the pancreas, an organ that secretes enzymes and hormones that help you digest food and regulate blood sugar.
The inflammation from both these conditions can cause severe pain, which can be worsened by eating regular foods due to the effort it takes your body to digest and absorb them.
Conversely, clear liquids require much less effort to digest and absorb, and you may tolerate them better.
This is because they contain very few proteins and fats and are mostly made-up of easily digestible carbohydrates (1).
A colonoscopy is a procedure in which a doctor uses a scope to look inside your colon.
It’s commonly performed as a screening for colorectal cancer or to help diagnose other intestinal problems.
In preparation for a colonoscopy, you may have to follow a clear liquid diet for one day and drink a laxative solution before the procedure (2).
This is to clean the bowel and allow the doctor to view the intestinal lining without obstruction from food residue.
However, several studies have demonstrated that a low-fiber diet — containing less than 10 grams per day — is as effective as a clear liquid diet for ensuring the bowel is empty before a colonoscopy (3, 4).
Still, many doctors recommend a clear liquid diet before the procedure, especially for hospitalized patients.
What is allowed on a clear liquid diet?
A clear liquid diet is very strict, allowing only clear liquids. The items can have color as long as they are transparent.
Examples include (1):
- water and ice
- translucent fruit juices without pulp
- tea or coffee with no added milk or cream
- clear soda
- sports drinks
- flavored gelatin, like Jell-O
- chicken, beef, or vegetable broths
- strained tomato or vegetable soup
If preparing for a colonoscopy, your doctor may have you avoid items that contain red or purple dye, such as certain flavors of Jell-O or sports drinks, because they can leave a residue in the bowel that may be mistaken for blood.
In either case, the diet helps maintain hydration, but it is nutritionally inadequate because of its strict limitations.
If necessary, you can follow the diet for several days if you drink clear protein drinks like Ensure Clear or other clear protein drinks (1).
You can buy Ensure Clear online.
One-day sample clear liquid diet
Here is an example of a one-day clear liquid diet with the inclusion of clear protein drinks:
- clear protein drink, which you can buy online.
- 1 cup (240 mL) black coffee
- lime soda
- 1 cup (240 mL) of strained tomato soup
- Jell-O pack
- 1 cup of tea with honey
- clear protein drink
- 2 cups (580 mL) of beef broth
- sports drink
Can the diet help you lose weight?
While not its intended purpose, a clear liquid diet can help you lose weight.
Due to its strict nature, the diet generally contains less than 1,000 calories.
With such a low-calorie diet, it would be impossible to meet your nutritional needs without a multivitamin and mineral supplement.
Even with a supplement, the diet lacks important nutrients that help you stay full, like protein and fiber.
Consequently, you would likely experience ravenous hunger along with fatigue and irritability after only a day or two from a lack of calories and nutrients.
That said, following a clear liquid diet is not a sustainable solution to weight loss.
For a safer and sustainable approach to weight loss, reduce the number of calories you consume by 500–750 per day (7).
This equates to approximately 1,200–1,500 calories per day for women and 1,500–1,800 calories per day for men.
The bottom line
A clear liquid diet restricts solid foods and allows only clear liquids such as juice, coffee, Jell-O, and broths.
Doctors often prescribe the diet as part of a treatment for conditions like diverticulitis and pancreatitis or as a preparation for procedures like a colonoscopy.
Because the clear liquid diet is very low in calories and contains inadequate nutrients, it is not a safe or sustainable diet for weight loss.