What is juice fasting?

During juice fasting, you avoid solid food for a limited time. Instead of meals, you drink fruit and vegetable juices throughout the day, along with plenty of water and herbal tea. The health insurer DAK describes it as a gentle form of fasting because your body continues to get vitamins and minerals from the juices (DAK, 2026). Avoid caffeine, alcohol, and sweetened drinks during this time.

The key word is limited. Juice fasting is not an eating plan for life, but a short break from your usual diet. Many people use those days to become more mindful of what they usually eat and drink. Whether a juice cleanse is right for you depends on your goal. For an honest answer, read our article on whether a juice cleanse really works.

The terms are often mixed up. In everyday use, juice fasting and a juice cleanse mean almost the same thing (DAK, 2026). A juice cleanse is usually a ready-made package, while juice fasting is more the method behind it. Traditional Buchinger therapeutic fasting, on the other hand, is stricter.

During therapeutic fasting, you have only around 0.25 liters of juice and 0.25 liters of broth per day, providing 250 to 500 kilocalories (DGE, 2018). Juice fasting provides more because the juices replace meals. Our comparison of juice fasting or water fasting shows just how much they differ.

Many juice cleanses use four to six juices a day, while others combine fewer juices with a shot and kombucha. So when counting calories during a juice cleanse, start with each bottle. According to the nutrition label, Supergreen contains 21 kilocalories per 100 milliliters, or around 105 kilocalories per bottle. Radiator, with apple, sweet potato, and carrot, contains 50 kilocalories per 100 milliliters, or about 250 per bottle. A day made up mostly of green juices is therefore at the lower end of the range, while a day with fruit-based varieties is at the upper end.

This creates the calorie deficit that comes with every cleanse. If you normally consume around 2,000 kilocalories and get 800 during the cleanse, you cut about 1,200 a day. Over three days, that’s around 3,600 kilocalories, which the body makes up from its reserves. That’s the core of every juice cleanse. It’s a deliberate break for a few days, not a long-term diet.

An example makes this easier to picture. Lena usually eats three meals and two snacks, totaling about 1,900 kilocalories. During her three-day juice cleanse, with juices, a shot, and kombucha, she gets around 800 kilocalories a day, and her hunger is strongest on the second afternoon. Since she knew this in advance, she keeps that afternoon completely free. Our article Juice cleanse: 3, 5, or 7 days explains how long a first cleanse should last.

Each fasting day follows a set rhythm. DAK recommends up to seven glasses of juice a day and advises following your usual mealtimes (DAK, 2026). This gives your day a familiar structure.

• Start the morning with a glass of water and your first juice.
• Have a second juice and herbal tea throughout the morning.
• At lunchtime, have a juice instead of a meal, ideally sitting quietly at the table.
• In the afternoon, have another juice and plenty of water.
• A mild juice rounds off the day in the evening, followed by tea only.

Along with drinking juice, the most important rule of juice fasting is to drink plenty of fluids. During fasting, at least 2.5 liters of water or herbal tea a day is recommended (ÄGHE, 2025). Drinking slowly also helps you savor the juices mindfully instead of gulping them down on the go.

Juice fasting isn’t just about the days when you drink juice. The days before and after are part of it too. The classic fasting schedule reflects this, with a preparation day beforehand and three days to ease back into eating afterward (DGE, 2018).

1. Preparation. For one or two days beforehand, eat lighter, avoid coffee and alcohol, and drink more water. Our article on preparing for a juice cleanse shows you exactly what this looks like. 2. Fasting days. Now you have only juices, water and tea. The first day or two are often the hardest. 3. Breaking the fast. Traditionally, you finish with an apple, eaten slowly or cooked (DGE, 2018). This officially marks the end of the fasting days. 4. Rebuilding. For a few days, eat lightly and in small amounts. Our article how to ease back into eating after a juice cleanse explains the process step by step.

Many people underestimate the final phase. If you eat a large meal right after juice fasting, you often get an upset stomach and quickly lose the good feeling from the cleanse.

And how long does the whole thing take? For beginners, one to three days is enough. DAK considers juice fasting for up to a week acceptable; it shouldn't last longer because of the risk of deficiencies (DAK, 2026). Find out which duration is right for you in our article Juice cleanse: 3, 5 or 7 days.

When you juice fast, your body gets less energy than usual. First, it draws on its sugar reserves, the glycogen in the liver. This reserve is largely depleted after about a day (ÄGHE, 2025). After that, the body gradually shifts to using more fat as an energy source. With juices, this shift probably takes longer than with water fasting alone, because the juices continue to provide some sugar.

The number on the scale often drops quickly. But that's usually water, not fat, and it quickly comes back once you return to your usual diet (DAK, 2026). Juice fasting is therefore not a way to lose weight long-term, but it can be a prompt to rethink your eating habits.

There is also some concerning data. In a small study, three days of juice alone changed the bacteria in the mouth and gut, presumably because of the lack of fiber (Northwestern University, 2025). This supports keeping cleanses short and choosing juices rich in vegetables.

Typical symptoms in the first few days include chills, fatigue or headaches (DAK, 2026). Read our article on headaches, chills and hunger to find out what's normal and what helps.

Juice fasting means replacing solid food with juice, water, and tea for a few days. It’s gentler than therapeutic fasting, but still needs to be well planned. Juice fasting includes preparation, fasting days, breaking the fast, and returning to normal eating—not just the juice days themselves.

Don’t expect miracles on the scales, because most of the weight lost is water. What often remains is a fresh perspective on your food. Choose vegetable-focused juices, drink enough, and keep the cleanse short. See the juice cleanse experiences to find out how each day can feel.