A liquid diet is often prescribed before certain medical tests or procedures. It can also be used before or after surgery on the gastrointestinal tract.
Clear liquid diets are meant to be followed only for a short time. They are not recommended for longer periods. A clear liquid diet is not meant to be used for weight loss.
This article explains why you might need to follow a clear liquid diet. You will also learn which liquids are considered “clear” and which are not.
What Are Clear Liquids?
Clear liquids are see-through. They do not have any solids or pulp in them. Foods that melt into clear liquids at room temperature, like ice pops and gelatin, are also allowed on a clear liquid diet.
Liquids that are not see-through (opaque) are not allowed on a clear liquid diet. These liquids take more work to digest. They also leave behind some solid pieces of food parts, like fiber, in your large intestine. This is called a residue. If you have residue in your intestines, it can affect the results of a test or procedure.
If you have specific health needs, some types of clear liquids might be better options for you. There might be some clear liquids that you will need to avoid. Here are a couple of examples:
Sugar-free liquids: Unless you are on a sugar-restricted diet, you should mostly choose liquids with sugar in them. The added sugar will provide you with calories. You need the calories to maintain your energy and blood sugar levels. However, if you have diabetes, ask your provider if you should choose low-sugar clear liquid options. Low-salt (sodium) broth or bouillon: Salt is an important nutrient for your body. However, if you’re on a low-salt diet, ask your provider if you should choose reduced-sodium or unsalted broth or bouillon while you’re on a clear liquid diet.
Avoiding Certain Colors
If you’re doing a bowel prep before a colonoscopy, you might be asked to avoid any red, purple, or blue liquids. The dyes or natural colors in these liquids can make it look like there is blood in your intestines during the test.
Here’s an example: If you’re prepping for a colonoscopy, you might decide to have juice as one of your liquids. The instructions for the prep say that you cannot have any blue, red, or purple liquids.
That means that you could choose white cranberry or white grape juice. You could not have red cranberry or purple grape juice.
Some flavors of gelatin, ice pops, and nutrition supplements also have red, purple, or blue dye. Make sure you check the labels carefully.
Typical Day of Eating
Try to eat or drink on a regular schedule while you are following a clear liquid diet. This will keep you hydrated and not too hungry. Your body digests clear liquids very quickly, which means they won’t be as satisfying as a full meal.
Keep in mind that caffeine could make you feel jittery or affect your sleep. If you have a cup of black coffee in the morning, you could still have it on a clear liquid diet. However, you might want to stick to decaffeinated drinks later in the day.
Purpose of a Clear Liquid Diet
A clear liquid diet helps clear out the digestive system. Cleaning up prevents undigested food from affecting the results of certain medical tests.
Breakfast
1 glass pulp-free fruit juice1 bowl gelatin1 cup of coffee or tea (without dairy products)Sugar or honey (if desired)
Snack
1 glass fruit juice (pulp-free)1 bowl gelatin
Lunch
1 glass fruit juice (pulp-free)1 glass water1 cup broth1 bowl gelatin
Snack
1 pulp-free ice pop1 cup coffee or tea (without dairy products) or a soft drinkSugar or honey (if desired)
Dinner
1 cup juice (pulp-free) or water1 cup broth1 bowl gelatin1 cup coffee or tea (without dairy products)Sugar or honey (if desired)
A clear liquid diet can also be used to give the digestive system a “rest” after surgery or during flare-ups of gastrointestinal diseases.
A clear liquid diet might be recommended before or after you have a procedure, such as:
Colonoscopy Endoscopy Bariatric (weight-loss) surgery
Sometimes, a clear liquid diet is recommended after a surgical procedure that does not involve the digestive system.
For example, if you have your tonsils out (tonsillectomy) it might hurt to swallow or chew food. Your provider might be recommended a day or two on a clear liquid diet as you start to heal.
You may need to use a clear liquid diet at times if you have certain medical conditions, such as:
Inflammatory bowel disease (IBD) Diverticulitis Pancreatitis
A clear liquid diet can also help your gut rest and heal after you have an illness that causes vomiting or diarrhea. For example, if you have the “stomach flu,” a clear liquid diet can help prevent you from getting dehydrated.
How Long Does It Last?
A clear liquid diet is very low in calories, protein, fat, and most nutrients. It is only meant to be used for a few days at most. You should not stay on a clear liquid diet for more than 3 or 4 days unless your healthcare provider tells you to.
Risks
A clear liquid diet is safe when you are under the care of a provider and you will only be on it for a short time.
Being on a clear liquid diet can have side effects and risks, including:
Feeling weak or dizzy Not getting enough nutrients Low blood sugar if you have diabetes Inaccurate test results (if you do not follow the diet)
A clear liquid diet can be a choking hazard if you have trouble swallowing (dysphagia). People with dysphagia have a hard time swallowing thin liquids.
Your healthcare provider or dietitian can talk to you about how to manage a clear liquid diet safely if you have dysphagia.
Tips
It can be challenging to stay on a clear liquid diet, even if it’s just for a day or two. Here are a few ways that you can make the experience easier:
Choose your favorite flavors of liquids (unless they are purple or red and you’ve been told to avoid these colors before a test)Pick out different types of liquids for some variety"Eat" your liquids regularly to keep yourself from getting too hungryDistract yourself with activities and hobbies that are not food-relatedDon’t overdo physical activity if you feel tired or weak
Summary
You might be asked to follow a clear liquid diet before certain medical tests and procedures. It can also give the digestive system a chance to rest after an illness.
Your body won’t get enough nutrition from a clear liquid diet, so you may feel more tired than usual. Don’t push yourself during this time, especially if you feel dizzy and weak.
A clear liquid diet includes liquids that you can see through, like tea, black coffee, apple juice, and clear broths. Some flavored gelatins and ice pops are also considered clear liquids.
However, you might be asked to avoid certain colors if you are having a test like a colonoscopy. Red-colored drinks or gelatin can look like blood in the digestive tract.
A clear liquid diet is safe if your provider is checking in with you and you will only be on it for a short time. Clear liquid diets do not provide enough calories and nutrition for long-term use. They are also not intended to be used to lose weight.
A Word from Verywell
Being on a clear liquid diet can help prepare your body for a medical test or procedure. It can also give your body a break after you’ve been sick or had a flare-up of a disease.
If you are asked to follow a clear liquid diet, be sure to follow the instructions. While the diet is safe to be on for a short time, it can still cause some side effects. If you are having a hard time following the diet, or it is making you feel unwell, call your provider.
