The Real Deal About Liquid Fasting

October 1, 2021


Diets consisting of liquids only have been serving their purpose for medical and cleansing reasons for years. In addition to that, you hear people talking about losing weight with the help of liquid fasting.

Some say it can bring outstanding results, such as quickly lost weight and detoxed body. Others doubt whether it is safe and actually beneficial. Let’s take a look at what science has to say about it.

What Is Liquid Fasting

Liquid fast means eliminating the intake of any solid food and consuming liquids instead. Because this diet cannot provide an adequate amount of nutrients, it shouldn’t be done for a prolonged period of time.

Generally, health experts do not recommend this type of fast to last more than 24 hours without doctor’s approval. Liquid fast or a liquid diet is normally prescribed by doctors before certain medical procedures, such as colonoscopies.

This diet can also be prescribed to tackle some digestive tract problems, such as diarrhea, diverticulitis or Crohn’s disease. Liquids are easy to digest and help to clean out body’s intestinal tract.

Liquid fast can also be done for religious reasons, to detox, lose weight, or for its health benefits. Because a clear liquid diet can't provide you with adequate calories and nutrients, it shouldn't be continued for more than a few days. Liquids that are allowed to include: 

  • Water
  • Tea without milk or cream
  • Coffee without milk or cream
  • Juices without pulp
  • Clear, low-fat broths 
  • Clear soups
  • Nutritional/sports drinks 
  • Plant-based milk
  • Gelatin
  • Popsicles

Consuming sugary, carbonated drinks technically is allowed, however, not recommended, as it may irritate the stomach and prevent weight loss. 

It's Benefits

Improved Cardiovascular Health

A study has shown that a 3-day juice fast decreased lipid peroxidation, the process in which free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage.

It also increased Nitric oxide concentration, which is a known vasodilator, Lack of bioavailable NO leads to arterial stiffness and increases blood pressure.

Both, the decreased lipid peroxidation and increased NO concentration, improve cardiovascular health.

Improved Immune System

Apparently, liquid fasting can also improve the immune system. According to some studies, increased concentration of the previously mentioned Nitric oxide plays an important role in the immune system.

If you would decide to take liquid fasting a step further and decided to go on a water fast, it could benefit your immune system even more. Research conducted by the University of Southern California has shown that just three days of water fasting can regenerate the immune system. 

Improved Digestion

In 2017 a study on the health benefit of vegetable/fruit juice-based diet was conducted. It tested 20 healthy adults by putting them on a fruit and vegetable juice diet for 4 days. It was observed, that after 4 days some of the gut bacteria, potentially related to improved digestion has significantly increased.

Besides that, doing a clear liquid fast lets your digestive tract take a break. Clear liquids are easy for the body to break down as they are low in protein and fat and mostly consist of carbohydrates that are easy to digest.

Lost Weight

Clear liquid diets are highly related to weight loss. That is because liquid diets tend to be low in calories. The previously mentioned study observed, that 4 days of juice cleanse lead to a significant decrease in weight and body mass index.

Participants lost up to 4 lbs. A 14-day follow up period showed that body weight remained decreased compared to the baseline weight. However, almost half of the lost weight was gained back.

Increased Hydration

This one sounds very obvious, however, is still important to mention. Four out of five Americans claim they are not drinking enough water. And we can’t stress the importance of water enough.

Drinking water boosts skin health and beauty, keeps blood pressure at norm, detoxifies, and is crucially important in the process of flushing body waste. And we know that the list could go on.

We think you might be interested: Everything You Need to Know About Water Fasting


Limited Research

Even though juice cleanses, liquid fasts and other similar diets are popular weight loss and health-improving methods, scientific research on that is quite limited. The wast majority of research on liquid fasts or diets is related to medical procedures, such as colonoscopy or certain surgeries, rather than weight management. This means promising results about liquid diets should be taken with a grain of salt.

The Lost Weight Might Come Back

Practise shows, that weight, lost with liquid diets tends to be regained as soon as calorie intake reaches the norm again. However, adopting a healthy diet after the liquid fast ends can help to maintain the lost weight.

Difficult To Get Enough Nutrients

Since liquid diets lack fat and protein, it is impossible to get all the needed nutrients. The calories come mostly as carbohydrates from sugars in juices or other drinks.

This is a good place to remind, that people can and do gain weight from liquids, such as sugary sodas, as they are high in calories. In order to achieve the best results with a liquid fast, try to aim for about 200 grams of carbohydrates.

Not A Long Term Solution

The previous drawback leads to this one. It’s simple - if you can’t get enough needed nutrients from a diet, you should not stick to the diet, as it can leave to deprivation, dizziness, and other health problems. 

Safety Cautions

If you have any of the following health conditions, please consult your doctor before going on a liquid fast.

  • Diabetes
  • Heartburn and other heart problems
  • Pregnant or breastfeeding
  • Chronic kidney disease
  • Individuals with eating disorders or are severely underweight
  • Taking specific medication for a health condition
  • Extreme athletes who are in season
  • Gout

Bottom Line

Short-term liquid fasting can be a helping tool in weight loss as well as benefit the body by letting the digestive tract rest. Extra hydration is always a good idea too.

However, it is not suitable as a long term option and should be done with time brakes. Safety cautions should also be considered.


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