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 insurance provider DAK describes it as a gentle form of fasting because the juices continue to provide the body with vitamins and minerals (DAK, 2026). During this time, you avoid caffeine, alcohol, and sweetened drinks.

The key word is limited. Juice fasting isn’t a way of eating forever, 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 makes sense for you depends on your goal. Our article offers an honest answer to the question of whether a juice cleanse really does anything.

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 the ready-made package, while juice fasting is more the method behind it. By contrast, classic Buchinger therapeutic fasting 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 include four to six juices a day, while others combine fewer juices with a shot and kombucha. So when you add up the calories in a juice cleanse, start with each bottle. According to the nutrition information, the green 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 around 250 per bottle. A day consisting mostly of green juices is therefore at the lower end of the range, while a day with fruitier varieties is at the upper end.

This results in the calorie deficit that every cleanse involves. If you usually consume around 2,000 kilocalories and have 800 during the cleanse, you cut about 1,200 a day. Over three days, that adds up to around 3,600 kilocalories, which your body makes up for from its stores. That’s the essence of any juice cleanse. It’s a conscious break for a few days, not a long-term diet.

An example makes it easier to picture. Lena usually eats three meals and two snacks, totaling about 1,900 kilocalories. During her three-day juice cleanse, with juice, 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 free. For guidance on how long a first cleanse should be, read our article Juice cleanse: 3, 5 or 7 days.

Every 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 in place of a meal, ideally sitting down and taking your time.
• In the afternoon, have another juice and plenty of water.
• In the evening, finish the day with a mild juice, then drink only tea.

Along with the juices, the most important rule during juice fasting is to drink plenty of fluids. At least 2.5 liters of water or herbal tea a day is recommended while fasting (ÄGHE, 2025). Drinking slowly also helps you savor the juices instead of gulping them down absent-mindedly.

Juice fasting consists of more than just the days of juicing. The days before and after are just as important. This is also reflected in the routine for traditional fasting, 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 meals, skip coffee and alcohol, and drink more water. Our article on preparing for a juice cleanse shows you exactly what to do. 2. Fasting days. Now you have only juices, water, and tea. The first one or two days are often the hardest. 3. Breaking the fast. Traditionally, this starts with an apple, eaten slowly or cooked (DGE, 2018). This officially marks the end of the fasting days. 4. Transition. For a few days, eat lightly and in small amounts. Our article easing back into eating after a juice cleanse explains the process step by step.

Many people underestimate the final phase. If you go straight back to eating large meals after a juice fast, you’ll often get an upset stomach and quickly lose the good feeling from the cleanse.

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

During a juice fast, the body gets less energy than usual. First, it draws on its sugar reserves: 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. This transition probably takes longer with juices than with a water-only fast, because juices continue to provide some sugar.

The number on the scale often drops quickly. But that’s usually water, not fat, and it comes back quickly once you return to your usual diet (DAK, 2026). Juice fasting is therefore not a way to lose weight permanently, but it can be a starting point for changing 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 fiber was lacking (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, feeling cold, and hunger to find out what’s normal and what helps.

Juice fasting means replacing solid food with juices, 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 easing back into eating - not just the days when you drink juice.

Don’t expect miracles on the scales, because most of the weight loss is water. What often remains is a fresh perspective on your food. Choose vegetable-based juices, drink enough and keep the cleanse short. The juice cleanse experiences show what each day can feel like.