A liquid diet involves consuming all or most calories from liquids. It's an appealing option because it can lead to quick calorie reduction and weight loss, supported by research. However, these results are often short-term, and regaining weight is common once regular eating resumes. While liquid diets offer simplicity and structure, they can also lead to feelings of deprivation and rebound weight gain without careful planning. Cutting your daily intake to drastically low levels can pose health risks. Prioritizing health and consulting a doctor before starting a liquid diet is essential, along with ensuring that shakes contain all necessary vitamins and minerals.
What is a Liquid Diet?
As the name suggests, a liquid diet means you're getting all, or at least most, of your calories from drinks. There are different kinds of liquid diets. A clear liquid diet, often medically prescribed, involves consuming only liquids you can see through. This type of diet is typically used for short periods to rest and cleanse the digestive tract while providing hydration and some energy. It excludes solid foods and liquids that aren't transparent. Clear liquids are easily absorbed, aiding digestion and allowing clear visibility during imaging tests like colonoscopies.
Why Choose a Liquid Diet?
Liquid diets are appealing because they can create quick results. For someone looking to get started, the simplicity and structure of these plans can feel like a fresh start. People choose liquid diets for various reasons, including rapid weight loss through reduced calorie intake. Liquid diets can work, like any diet that gives you fewer calories than you use. These diets can help by taking the guesswork out of portion control. They’re also beneficial if you have trouble chewing food. Some also believe in their detoxifying effects, though scientific evidence supporting this is limited. Others may use it as part of a spiritual practice.
Types of Liquid Diets
There are several types of liquid diets, each with its own characteristics and purposes.
Clear Liquid Diet
A clear liquid diet is medically prescribed for short periods to rest and clean out your digestive tract while providing adequate short-term hydration and some energy. Just like it sounds, the diet consists of clear liquids and foods that melt into clear liquids (like Jell-o®). It excludes solid foods and liquids that you can’t see through (like milk). Clear liquids are easily absorbed by your digestive system, and they also allow technicians to see clearly into your digestive tract during an imaging test, such as a colonoscopy. The diet is usually prescribed for one of three reasons:
Read also: Bikini Competition Prep Guide
- To clear out your digestive tract and/or prevent nausea before a procedure, such as an imaging test or surgery.
- To give your digestive system a rest from severe gastrointestinal symptoms, such as inflammation, vomiting, and diarrhea.
- To offer nutrition without eating after a fast or surgery. Surgery in your digestive system may require a few days to rest the affected organs afterward. Other surgeries may require the diet for just 24 hours afterward until your anesthesia wears off.
Full Liquid Diet
A full liquid diet includes all liquids and foods that become liquid at body temperature. Shakes, milk, frozen yogurt and creamy soups are allowed, as long as they don’t have any chunks or food particles in them. A full liquid diet is prescribed for similar reasons as the clear liquid diet - to rest the digestive system after illness or surgery and reintroduce it slowly to normal eating - but it’s a less severe diet for less severe cases. Some people need to start on the clear liquid diet first before progressing to the full liquid diet. Those who are preparing for an imaging test will need to stick to clear liquids to keep their digestive tract clear.
Meal Replacement Liquid Diets
Some liquid diets involve meal replacement shakes, which are consumed in place of solid foods. Numerous companies sell these shakes for weight loss purposes. Meal replacement shakes are often lower in calories than typical meals. They can replace one or multiple meals each day. They are designed to contain all the nutrients your body needs to function, including macronutrients (protein, carbs and fat) and micronutrients (vitamins and minerals). Some weight loss programs use these shakes to account for your entire calorie intake for up to several months.
Detox Diets and Cleanses
Other liquid diets include detox diets or cleanses, which require the consumption of certain juices or drinks that supposedly remove toxic substances from your body. Unlike meal replacement shakes, these programs typically rely on a few natural ingredients like juices from certain fruits and vegetables and other botanical ingredients. Because of this, these diets may not contain all the nutrients your body needs.
What Can You Eat on a Clear Liquid Diet?
The clear liquid diet includes:
- Coffee and tea without milk or non-dairy creamer (sugar or honey is OK).
- Clear, nonfat broths.
- Strained, pulp-free fruit and vegetable juices.
- Sodas and sports drinks.
- Clear nutritional drinks.
- Pulp-free popsicles.
- Jell-o®.
Your healthcare provider will give you more specific directions on the amounts of each type of liquid you should consume. If the diet is prescribed before an imaging test, you might be asked to exclude the color red. Red liquid can resemble blood on an imaging test.
Read also: Transformations with Ozempic
Potential Benefits of a One Week Liquid Diet
The health benefits are primarily from giving your digestive system a chance to rest and heal from severe symptoms.
- Weight Loss: By consuming only juice for a week (and very light meals for two additional weeks), you’ll trim your calorie intake considerably. Liquid diets often contain fewer calories than diets consisting of solid foods. Replacing some or all meals with liquid meal replacements can promote weight loss.
- Digestive Rest: If you have inflammation from pancreatitis, gastritis, or inflammatory bowel disease, the clear liquid diet can give it a chance to calm down. If you have diverticulitis, an infection in your colon, the inflammation is aggravated by poop in the colon. A clear liquid diet for a few days can help clear that out.
- Hydration and Electrolyte Restoration: If you have severe diarrhea or vomiting, the clear liquids can restore your depleted water, energy, and electrolytes without triggering further diarrhea or vomiting.
- Convenience: As soups and shakes are easy to make at home, this diet isn’t too time-consuming. You don’t need to spend hours in the kitchen preparing meals for yourself every day.
Risks and Considerations
While liquid diets can deliver fast results, they aren’t built to last. Quick results often come with drawbacks. Without careful planning, they can leave you feeling deprived and even set you up for rebound weight gain. Cutting your daily intake down to 400 can put your health at risk. Without enough calories and nutrients, your body can’t function properly, and the side effects can be serious.
- Malnutrition: It’s safe to limit calories and nutrition for short periods, but you risk malnutrition if you stay on the clear liquid diet for more than five days. Healthcare providers will rarely recommend this. If they do, they will prescribe supplements to enhance your nutrition.
- High Blood Sugar: If you have diabetes, you may need to discuss this with your healthcare provider before proceeding with the clear liquid diet. You may need to find sugar-free alternatives to some of the liquids, adjust your medications, and monitor your blood sugar carefully during the diet. Fruit juice is very high in sugar, which can cause high blood sugar in someone with diabetes or prediabetes.
- Unsustainable Weight Loss: Rapid weight loss isn’t usually lasting weight loss. Though a juice fast might melt away pounds quickly, it’s not a long-term solution - and could lead to a cycle of yo-yo dieting.
- Nutrient Deficiencies: Though fruits and vegetables have lots of important nutrients, they’re notably lacking in protein, fat, and certain micronutrients like vitamin B12. Going without these nutrients for too long could lead to deficiencies.
- Changes from Low Fiber: A study published in 2025 found that juice diets lacking in fiber caused harmful changes to oral and gut bacteria after just three days. Meanwhile, low fiber intake could slow down your digestion, causing constipation. One side effect of a liquid diet is constipation, which may be due to the low fiber content of most liquids.
- Fatigue: As you’re consuming very few calories and nutrients on a liquid diet, you’ll feel fatigued most of the time.
- Social Isolation: The restrictive nature of a 21-day juice fast could mean three weeks of difficulty socializing over meals. During this time, you might lose out on the pleasure of enjoying food with others.
- Swallowing Problems: If you have dysphagia or another swallowing problem, you might need to discuss thickeners with your healthcare provider to thicken your clear liquid diet to a consistency you can more easily swallow.
- Risk of Gallstones: Additionally, very low-calorie diets (500 calories per day) may lead to a higher risk of gallstones than low-calorie diets (1,200-1,500 calories per day).
Who Should Avoid Liquid Diets?
A liquid diet is not advisable for people who are suffering from health conditions such as diabetes as some of these diets can cause hyperglycemia or hypoglycemia.
Several groups of people should not consider a liquid diet, such as pregnant or nursing women, children and adolescents and those who are underweight.
Important Considerations Before Starting
- Consult Your Doctor: Always prioritize your health first. Before starting a liquid diet, speak with your doctor. If you want to go on one for weight loss, talk to your doctor first about whether a liquid diet is appropriate for you. Pregnant or nursing women, and people who take insulin for diabetes, or anyone with a chronic illness shouldn't go on a liquid diet.
- Registered Dietitian: If your doctor gives you the OK to go on one, you should also see a registered dietitian, who can go over it with you and make sure you're getting enough calories and nutrition. Your dietitian might recommend that you take a vitamin or nutritional supplement while you're on the liquid diet.
- Nutritional Content: It’s also important to make sure that your shakes contain all the recommended vitamins and minerals you need. Before you choose a liquid diet plan, know what you're drinking. If you're considering one of the commercial diets, look at the daily values on the nutrition facts label. Be sure you're getting 100% of all the recommended vitamins and minerals. Look for a diet that is not too low in calories and contains plenty of protein and fiber to keep you feeling full while you lose the weight gradually.
How Long Should You Stay on a Clear Liquid Diet?
The diet is usually only prescribed for a few days. If it is prescribed for longer, it will be modified with certain supplements to provide more adequate nutrition over the longer term. The maximum number of days for a liquid diet is typically two weeks, but this should only be done under medical supervision.
Read also: Dangers of the 800 Calorie Diet
Discontinuing a Clear Liquid Diet
Contact your healthcare provider if you experience:
- Stomach pain or cramping.
- Severe weakness.
- Difficulty swallowing.
Liquid Diets and Weight Loss
Liquid diets can work, like any diet that gives you fewer calories than you use. These diets can help by taking the guesswork out of portion control. They’re also beneficial if you have trouble chewing food.
Replacing some or all meals with liquid meal replacements can promote weight loss. However, this is due to a reduced calorie intake. Both food-based and liquid-based diets are equally effective when they contain the same number of calories.
However, the results may not last. When you drastically cut calories, your metabolism slows to save energy. Unless you change your eating habits, you're likely to regain the weight you lost after you go off the liquid diet.