A clear liquid diet requires very little energy for the body to digest. Doctors may prescribe this diet in preparation for certain surgeries and medical procedures, or as a temporary remedy for gastrointestinal distress.
Some alternative health advocates also recommend a clear liquid diet when fasting or to detox the body.
In this article, we look at why a clear liquid diet is used, as well as the risks and benefits.
Clear liquids are easier for the body to digest. This means they leave nothing behind in the digestive tract, making it easier for doctors to perform a range of procedures.
A clear liquid diet will vary depending on why a doctor has recommended it, so it is important for users to get a clear list of what is and is not allowed.
A clear liquid diet usually includes:
- clear juices without pulp
- electrolyte drinks, ginger ale, and club soda
- clear broths
- plain popsicles that do not contain pureed fruit or chunks
- hard candy
- gelatin products, such as Jell-O
- tea without milk or cream
Some clear liquids are forbidden on a clear liquid diet. These include:
- soda and cola
- alcoholic drinks
- tomato and vegetable juices
- dairy products
Liquids with red or purple coloring may also need to be avoided because they leave coloring in the intestinal tract that can look like blood. This makes it harder for doctors to get an accurate result with intestinal screening tests.
A person should not eat any solid foods, even fruits and vegetables, on a clear liquid diet.
Doctors generally recommend a clear liquid diet for one of the following reasons:
Preparation for a medical procedure
A clear liquid diet can ensure that there is nothing left behind in the intestines before a medical procedure. This makes it easier to diagnose a variety of medical conditions.
Doctors may recommend a clear liquid diet before a colonoscopy, which is a procedure where a doctor examines the inside of the bowels. Certain other medical procedures may also require several days on a clear liquid diet, such as surgery on the intestines.
In most cases, it will also be necessary to fast immediately before surgery.
Recovering from a medical procedure
Some medical procedures can affect the ability of the body to digest and absorb food. A clear liquid diet allows the body to slowly recover, reducing the risk of nausea and making it easier to absorb nutrients.
Following bariatric surgery, for example, doctors typically recommend consuming only clear liquids to begin with. Over time, it will be safe to add other foods to the diet under the guidance of a doctor.
Preventing gastrointestinal distress
A clear liquid diet can be helpful after a period of nausea, vomiting, or diarrhea. Clear liquids are easier to digest and can reduce the severity of some stomach viruses. Switching to a clear liquid diet may also prevent dehydration.
People who are vulnerable to nausea due to chemotherapy, certain medications, or other medical conditions may benefit from trying a clear liquid diet at certain times.
For instance, in the days following chemotherapy, a doctor might recommend a clear liquid diet, particularly to a person who has a history of intense nausea.
A clear liquid diet is not a long-term health solution. In the short term, its benefits include:
- easier digestion that may prevent nausea and vomiting
- clearing the intestines, making it easier to perform certain medical procedures
- providing hydration and nourishment
A clear liquid diet offers fewer nutrients than a balanced diet rich in proteins, whole grains, fruits, vegetables, and other foods. Over time, it can lead to malnourishment, particularly in people who are already nutritionally deficient.
Clear liquid diets are especially risky for the following groups:
- underweight people
- people with nutritional or electrolyte imbalances
- people with eating disorders
- people with certain endocrine disorders
People with diabetes may experience dangerous blood sugar swings if a doctor does not monitor them during a clear liquid diet.
A clear liquid diet is not a safe option for weight loss. Moreover, this weight loss strategy is not likely to work over time. Once a person begins eating normally, they may quickly regain any weight they have lost.
People who follow a clear liquid diet for an extended period of time or who do so without a medical reason can experience a wide range of symptoms, including:
People should report any symptoms related to a clear liquid diet to their doctor promptly. If the diet is necessary, the doctor may be able to adjust it or recommend ways to reduce hunger and prevent uncomfortable side effects.
For most people, the biggest challenge of a clear liquid diet is feeling hungry. A clear liquid diet is not a complete and balanced diet, so it is common to experience food cravings while following one.
Some strategies that can help make the diet more comfortable include:
- drinking a nutritional supplement approved by a doctor
- drinking an electrolyte drink
- eating a variety of flavors, such as sweet gelatin and salty electrolyte drinks, to prevent cravings
- consuming clear liquids more frequently than regular mealtimes
- keeping hydrated with plenty of water
It is important to follow the diet a doctor recommends closely. Even a single solid food snack may mean rescheduling a medical procedure.
For people struggling with nausea, eating solid food during a clear liquid diet can mean more vomiting and painful dehydration.
A doctor can help with selecting the right clear liquid diet, and offer tips for fighting hunger and cravings.
For most people, a clear liquid diet is a temporary inconvenience that may offer better health, relief from nausea, or a safer medical procedure.