Fasting has become an increasingly popular health and wellness trend in recent years. Proponents claim that periodic fasting can help with weight loss, improve cardiovascular health, and even extend lifespan. But there are different types of fasting, ranging from complete abstinence from all food and drink except water to various juice and liquid diets. In this article, we’ll take an in-depth look at juice fasting and how it compares and contrasts with other forms of fasting.
What is juice fasting?
A juice fast, also sometimes called a juice cleanse or juice detox, involves consuming nothing but fruit and vegetable juices for a set period of time, usually between 1-7 days. On a juice fast, solid foods are eliminated and dietary intake is limited to juices made from fresh fruits and vegetables, sometimes with the addition of spices like cayenne pepper or cinnamon. Most juice fasts also allow for the consumption of herbal teas and water.
The rationale behind juice fasting is that by removing solid food and providing the body with concentrated micronutrients in liquid form, the digestive system can rest and the body can devote energy to cleansing and healing itself. Juice fasts are touted as a way to “detox” the body, promote weight loss, improve energy levels, and stimulate healing.
Rules and guidelines of juice fasting
There are no strict universal guidelines for juice fasting, but there are some general rules people tend to follow:
- Only fresh, raw vegetable and fruit juices are allowed. Pre-made or pasteurized juices are not recommended.
- Juices should be consumed immediately after preparation to prevent oxidation and loss of nutrients.
- Most juice fasts recommend six to eight glasses of juice per day, along with unlimited calorie-free beverages like water, herbal tea, or seltzer.
- You can vary the juices each day or stick with a set regimen.
- Some juice fasts allow small amounts of nuts, seeds, broths or plant-based proteins like legumes or tofu. Others restrict intake to just produce.
Here is an example one-day juice fast regimen:
|7 AM||16 oz lemon water|
|9 AM||12 oz green juice made with spinach, kale, cucumber, celery, ginger, lemon|
|11 AM||12 oz fruit juice made with apple, carrot, beet, orange|
|1 PM||12 oz vegetable juice made with tomato, carrot, beet, parsley|
|3 PM||12 oz green juice|
|5 PM||12 oz fruit juice|
|7 PM||Herbal tea|
Claimed benefits of juice fasting
Advocates claim that juice fasting offers many benefits, including:
- Weight loss – By abstaining from solid food and significantly reducing calorie intake, juice fasts can lead to rapid weight loss, especially in the short-term.
- Toxin elimination – Proponents believe that juice fasts support detoxification by resting the digestive tract and allowing the body to put more energy into elimination.
- Increased nutrient absorption – Some claim that nutrient absorption is greater from juices than from solid foods.
- Improved energy – The natural sugars in fruit juices can provide an energy boost.
- Reduced inflammation – The nutrients in juices may help reduce inflammation.
- Improved skin and gut health – Juice fasts promote the intake of antioxidants, phytochemicals, and probiotics that may benefit skin and gut health.
However, many of these proposed benefits are anecdotal and not yet conclusively proven by scientific research.
Potential risks and side effects
Despite the hype surrounding juice cleanses, there are some potential downsides and risks to consider:
- Hunger and cravings – Juice fasts involve dramatically reducing calorie intake, which can lead to hunger, irritability, cravings, and other symptoms.
- Lacks fiber and protein – Juices lack the fiber and protein contained in whole vegetables and fruits.
- Nutrient deficiencies – An all-juice diet does not provide adequate nutrition for extended periods of time.
- High glycemic load – The natural sugars in juices can cause spikes and crashes in blood sugar levels.
- Dental erosion – Some fruit juices are acidic and can erode tooth enamel over time, especially without brushing.
- Not sustainable – Once resumed, poor eating habits can easily lead to weight regain.
Some people also experience side effects like headache, fatigue, nausea, dizziness, irritability, constipation, or diarrhea while juice fasting. These often go away after the first few days as the body adjusts.
Is juice fasting actually healthy?
The health impacts of juice fasts are controversial. On the one hand, drinking vegetable and fruit juices floods the body with vitamins, minerals, antioxidants, and phytochemicals. This can potentially benefit health and support detoxification in the short-term. However, there are also drawbacks:
- Lacks protein, fat, fiber – Juice fasts are deficient in essential macronutrients. Protein helps maintain muscle mass and satiety. Fiber supports gut health. Fat helps absorb fat-soluble vitamins and provides fatty acids.
- Extremely low in calories – Juice diets provide only 600-1200 calories per day. Very low calorie intake can slow the metabolism.
- Nutritional deficiencies – An all-juice diet does not provide complete nutrition for more than a few days, putting you at risk of deficiencies in calcium, vitamin D, iron, zinc, and other nutrients.
- Blood sugar spikes – The liquid carbohydrates in juices are absorbed very quickly, spiking blood glucose.
Evidence suggests juice fasts and cleanses do not actually eliminate toxins or improve health in the ways claimed. The body already has its own highly sophisticated detoxification systems for removing waste and toxins.
How does juice fasting compare to water fasting?
Like juice fasting, water fasting involves abstinence from all food, but allows only calorie-free beverages like water, unsweetened tea, or black coffee. Here’s how the two types of fasts compare:
|Juice Fast||Water Fast|
|Allowed beverages||Fruit and vegetable juices||Water, unsweetened tea/coffee|
|Calories consumed||600-1200 calories||0-50 calories|
|Nutrition||High in vitamins and minerals but lacks protein, fat, and fiber||No macro- or micronutrients consumed|
|Potential benefits||Weight loss, toxin elimination, increased energy||Weight loss, autophagy, insulin sensitivity|
|Drawbacks||Hunger, nutritional deficiencies, blood sugar spikes||Hunger, fatigue, nausea, nutritional deficiencies|
|Difficulty||Easier due to juice calories||More challenging due to zero calories|
Water fasting is more extreme and thus may produce faster results like weight loss or autophagy, but it is also more likely to cause side effects and is not suitable for extended periods of time. Juice fasting is easier to comply with but does not confer the same metabolic benefits of a true water fast.
How does juice fasting compare to intermittent fasting?
Intermittent fasting (IF) simply involves going extended time periods between meals, anywhere from 12-48 hours. Some examples of popular IF regimens include:
- 16/8 – A 16 hour fast followed by an 8 hour eating window.
- 5:2 – Two non-consecutive days of severe calorie restriction per week.
- Alternate day – Alternating days of normal eating and fasting.
- 24 hours – One 24 hour fast 1-2 times per week.
Unlike juice cleansing, intermittent fasting allows normal meals rather than just juices. Here is how intermittent fasting and juice fasting compare:
|Juice Fast||Intermittent Fasting|
|Food allowed||Juices only||Normal meals|
|Fasting duration||24 hours – 7 days||12-48 hours|
|Frequency||One-time cleanse||Regular regimen|
|Nutrition||Deficient||Adequate if eating window is large enough|
|Benefits||Short-term detox||Weight loss, metabolic health, anticancer|
|Downsides||Extreme hunger, nutritionally inadequate||Hunger, cravings during fasts|
For most people, intermittent fasting is more sustainable long-term than juice fasting since it allows normal eating during designated windows. However, periodic short juice fasts can provide a reset.
Should you try a juice cleanse?
The evidence on juice cleanses is mixed. On the one hand, they flood your body with concentrated micronutrients and can provide a short “detox.” But they are also nutritionally inadequate for the long-term and may cause side effects.
Here are some things to consider if you are thinking of trying a juice cleanse:
- Only do short cleanses of 1-3 days, not extended cleanses.
- Make sure to include both green veggies and fruits in juices.
- Add ingredients like nuts, seeds, or plant protein to keep juices more balanced.
- Listen to your body and stop if you experience negative side effects.
- Consider doing intermittent fasting instead for longer-term fasting benefits.
- Transition slowly back into normal eating after a juice fast.
Overall, periodic short juice fasts are likely safe for most people and can provide a “reset.” But they should not be viewed as a standalone solution for detox or weight loss. Instead, focus on consistent healthy eating, managing stress, exercising, and getting enough sleep.
Juice fasting or juice cleansing involves consuming only fruit and vegetable juices for a short period of time to detox and provide the body with concentrated nutrients. However, juice fasts are nutritionally inadequate for the long-term compared to intermittent fasting or a balanced diet. Juice fasts can produce short-term weight loss and help you reset unhealthy eating habits for a time. But don’t view them as a magic bullet for detox and weight loss. Instead, focus on sustainable healthy lifestyle habits likenutrition, exercise, stress management, and rest.