What to Expect During a Juice Fast

Juice fasting works different for everyone.
Image Credit: Dean Mitchell/iStock/GettyImages

Juice fasting is one of the most popular yet controversial practices. On one hand, experts say that juices are healthy and nutritious. On the other hand, research shows that they're just as harmful as soda. The truth is that a juice detox plan will work differently for everyone.



  • Juice fasting is different for everyone. Some dieters experience increased energy and stamina, better sleep, weight loss and enhanced mental focus from the first few days. Others report nausea, fatigue, headaches, poor sleep and lethargy.

  • Start with a two- or three-day fast to see how your body reacts. If you have diabetes or other health conditions, talk to your doctor before starting a juice fast. Consume a variety of fruit and vegetable juices to boost your nutrient intake and get more antioxidants in your diet.

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How Juice Fasting Works

Before starting this journey, it's important that you know what to expect. While it's true that juice fasting may boost your health and well-being, it can also turn against you. Prolonged fasting, for example, will affect your body differently than a two- or three-day juice fast. The longer the fast, the higher the risks.

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This eating pattern involves drinking fresh fruit and vegetable juices for several days to several weeks. Some versions allow the consumption of whole fruits and veggies, though. Dieters may also drink unsweetened iced tea, herbal tea, green smoothies and water. Some fasting protocols include dietary supplements, colon cleansing formulas and other "detox" products.

Unfortunately, there is little evidence to support the whole "detox" concept. According to a review published in the Journal of Human Nutrition and Dietetics in December 2014, the few studies that show a correlation between detox diets and toxin elimination are either flawed or too small to provide any conclusive results. Furthermore, all clinical trials have been conducted on animals, not humans.

Perhaps you're hoping that a juice detox plan will help you shed fat. You might drop a few pounds, but you'll lose lean mass as well.


Most juices are low in protein, the building block of your cells and tissues. Your body needs this nutrient to build, repair and preserve muscle. Additionally, juice fasting and detox diets, in general, don't produce lasting results in terms of weight loss, as the National Center for Complementary and Integrative Health notes.

Read more: 9 Unhealthy, Even Dangerous Weight-Loss Diets


Is It Safe?

Fruit juice consumption is controversial, too. A May 2019 study published in JAMA Network Open has linked the consumption of sugary beverages, including fruit juice, to higher mortality rates.

As the researchers note, each additional daily serving (12 oz.) of fruit juice increases all-cause mortality risk by a whopping 24 percent. Surprisingly, the risk of death from all causes increases by only 11 percent for each extra daily serving of soda.



But that's not all. Scientists suggest that sugary beverages may also contribute to the onset of coronary heart disease, obesity, diabetes and insulin resistance. These potential side effects have been attributed to fructose, a sugar in fruit juice, and some soft drinks.

Read more: The Top 10 Beverages to Avoid

Fructose triggers a chain reaction in the body, causing inflammation, altered blood lipids and elevated blood pressure. Additionally, it promotes fat storage in the abdominal area.


As mentioned earlier, juice fasting can work for or against you. A December 2018 study featured in the British Journal of Nutrition found that drinking up to seven glasses of fruit juice per week can significantly reduce the risk of cardiovascular disease and coronary heart disease. Subjects who consumed either one to four glasses or four to eight glasses had a lower risk of stroke.

As you can see, this study contradicts the one published in JAMA Network Open. However, its authors point out that whole fruits are better than fruit juice because their health benefits are more conclusive.


Consider a smaller study, which appeared in Scientific Reports in May 2017. While the study was small, it is one of the few that illustrate the effects of juice fasting, showing that a three-day juice fast caused positive changes in the gut flora associated with weight loss. Its authors reported that juice fasting also decreased lipid oxidation and increased nitric oxide levels, which may lead to improved cardiovascular health.

The Stages of Juice Detox

The above findings show that juice consumption may improve overall health. The key is to enjoy juices in moderation. Juice fasting can be good for you as well, even though more research is needed to assess its safety and potential benefits. A short fast is unlikely to affect lean mass or put your health at risk.



First of all, determine how long you want to fast. Set realistic goals, whether it's weight loss or better health. A juice detox plan won't transform your body or cure diseases, but it can boost your nutrient intake. This experience is different for everyone, so it's hard to tell what to expect on a juice fast day-by-day. Consider starting with a one- or two-day fast to see how you feel.

Most dieters and health bloggers say that the first three days of fasting are the most challenging. You may experience dizziness, hunger pangs, intense cravings, poor mental focus and overall weakness. The good news is that fruit juices are quite high in sugar, so at least you'll have some energy. Water fasting, by comparison, cuts out calories and sugar, leaving you feeling tired and sluggish.

Depending on your carb intake during fasting, you may lose water weight from day one. The carbs in your diet are converted to glucose and used for energy. The excess is stored as glycogen in your muscles and liver. Each gram of glycogen is stored with at least 3 grams of water.

If you drink mostly fruit juices, you might gain water weight. Vegetable juices, on the other hand, are low in carbs and will have the opposite effect. Mango juice, for example, boasts 32.9 grams of carbs and 29 grams of sugars per cup. Each cup of vegetable juice has approximately 10 grams of carbs and 7 grams of sugars, depending on the ingredients used. As you see, there's a big difference between the two.

Read more: Can a High-Carb Diet Make You Retain Water?

Most dieters have mixed results when it comes to juice fasting. Some say that their energy went through the roof after three or four days of juicing. They experienced improved mental focus, weight loss, better sleep, reduced hunger and more. Others report feeling tired, lethargic, hungry and moody.

It's important to realize that juice fasting deprives your body of protein, fats and other nutrients. That's why it's not recommended to fast for more than a couple of days in a row. Start with baby steps and listen to your body. If you have kidney disease, diabetes, high blood pressure and other conditions, consult your doctor beforehand.




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