Updated: October 2026
In short: You can combine intermittent fasting and a Juice Cleanse, but not as a fasting window plus juice: juices contain calories and, strictly speaking, break the fast. A half-day Juice Cleanse, where two to three juices replace breakfast, works well as an everyday plan. If you have a pre-existing condition or take medication, talk to your doctor first. As of: October 2026.
Many of you ask whether you can combine the two approaches. Yes, as long as you're clear on the rules. Here's a 14-day plan, the nutritional values of frank. juices and a cost breakdown.
Can I combine intermittent fasting with a Juice Cleanse?
Yes, but as a deliberate hybrid. With classic intermittent fasting, the fasting period stays calorie-free, so just water and unsweetened tea. A juice contains calories and ends that fast. So don't put juice in your fasting window; use juices as a planned part of your eating window instead.
In practice: you drink two to three juices in the morning instead of breakfast and eat normally at lunch and dinner. That's a half-day Juice Cleanse. If you want to take the cleanse on properly, you'll find everything in Juice Cleanse Guide: How Do I Fast Properly?
What's in a frank. juice?
frank. juices are cold-pressed and HPP-treated, vegan, with no added sugar and no preservatives. One bottle holds 330 ml and keeps for about 14 days after delivery when stored at 2 to 8 degrees. The Juice Cleanse consists of six juices per day. Nutritional values per cleanse day (3-, 5- and 7-day cleanses):
| Variant | kcal/day | Carbohydrates | of which sugar | Protein | kcal per bottle (calculated) |
|---|---|---|---|---|---|
| Starter | 934 | 174 g | 160 g | 17 g | approx. 156 |
| Medium | 799 | 137 g | 124 g | 21 g | approx. 133 |
| Pro | 680 | 108 g | 97 g | 23 g | approx. 113 |
The right-hand column is a calculated average (daily value divided by six), not a figure for each individual flavour. The sugar comes from fruit and vegetables, which is the natural fruit sugar in the juice. If you're particularly mindful of sugar, choose Medium or Pro.
What does a 14-day plan look like?
The plan builds up the fasting time slowly and brings in juices as breakfast. It's a suggestion from our own experience, not a study.
| Days | Fasting window | Morning | Rest of the day |
|---|---|---|---|
| 1 to 3 | 12/12 | Normal breakfast | Eat normally, water and tea |
| 4 to 6 | 14/10 | 1 juice instead of breakfast | Balanced lunch and dinner |
| 7 | Rest day | Optional 1-day Juice Cleanse | Plenty of water and tea |
| 8 to 10 | 14/10 to 16/8 | 2 juices as first meal | Normal lunch and dinner |
| 11 to 13 | 16/8 | 2 to 3 juices, two meals | Vegetables, protein, little sugar |
| 14 | Rest day | Easy day | Break the fast with soup |
The rest days on day 7 and 14 aren't a must. They show that more isn't automatically better.
What does it cost over 14 days?
A worked example based on single prices: one juice in the box of 8 costs 36 EUR, so 4.50 EUR per bottle. If you drink two juices as breakfast for 14 days, that's 28 bottles, around 126 EUR (as of October 2026, prices from). You have to order in boxes of eight, so you'd end up with four boxes and 144 EUR.
A 1-day Juice Cleanse starts at 35.50 EUR, which is six juices a day and about 5.92 EUR per bottle. The comparison shows that half-day versions are cheaper than full cleanse days. With the Juice Cleanse cost calculator you can try out the numbers for yourself.
How does a half-day Juice Cleanse fit in instead of breakfast?
A juice isn't a full meal. It contains hardly any protein or fibre, so you should pair it with a protein-rich meal at lunch, such as lentils, eggs or quark. The idea: juices deliver fruit and vegetables in liquid form, but they don't replace a plate of vegetables.
Good morning combinations are The Purist (cucumber, celery) for a very light start or Marvellous Greens (apple, cucumber, spinach). Breakfast then stays deliberately small. You can read about how vegetable juices can help while fasting in Why You Should Drink Vegetable Juices While Fasting.
What does a day in week 2 look like?
An example for day 11 with 16/8 and an eating window from 8 am to 4 pm, designed around an office day:
| Time | What |
|---|---|
| 7:30 | Water or unsweetened tea |
| 8:00 | Juice 1 (for example Marvellous Greens) |
| 10:30 | Juice 2 and a handful of nuts |
| 12:30 | Lentil or vegetable dish with protein |
| 15:30 | Small snack, for example quark |
| 16:00 | Window closes, then water and tea |
Dinner is skipped in this example. The plan suits days packed with appointments, when breakfast would otherwise get lost. If you'd like to eat in the evening, shift the window later, say 11 am to 7 pm, and drink the juices from 11 am. The example is meant to show how the building blocks fit together, not to be a fixed rule.
If you notice you get ravenous with two juices in the morning, add protein instead of juice. The combination should make your start easier, not create extra hunger.
Who is this combination not suitable for?
Healthline and the Cleveland Clinic name the same risk groups for intermittent fasting: pregnant women, breastfeeding women, children, people with a history of eating disorders, underweight people, and people with diabetes or a tendency towards low blood sugar. For the frank. Juice Cleanse, the following also applies: not suitable for pregnant or breastfeeding women, children and people with a weakened immune system.
If you take medication, especially for diabetes or high blood pressure, talk to your doctor first. Depending on the variant, the Juice Cleanse contains between 97 and 160 g of sugar per day, which your blood sugar may notice. More information in When a Juice Cleanse Doesn't Make Sense.
What do I eat after the combination?
End each cleanse day or the 14 days with light food: soup, steamed vegetables, potatoes, a little protein. Only after two to three days do you go back to larger portions. Your stomach needs time, and you'll learn more quickly when you're full. You'll find ideas in What Is Best to Eat After a Juice Cleanse?
Drink at least one litre of still water or herbal tea alongside. That's what the brand recommends for the Juice Cleanse. It's best to skip coffee and alcohol during this time; you can read more in Coffee, Nicotine and Alcohol: Things to Avoid During a Juice Cleanse. Also plan a calm day in case you notice headaches or feeling cold.
Pairs well with frank.
If you'd like a trial run before 14 days, start with the 1-Day Juice Cleanse from 35.50 EUR (as of October 2026). It shows you how you react to six juices a day. Important: a Juice Cleanse is not a substitute for advice if you have a pre-existing condition.
You might also like
- Why You Should Drink Vegetable Juices While Fasting
- Juice Cleanse vs. 5:2 Intermittent Fasting: Which Suits Me Better?
- Juice Cleanse Guide: How Do I Fast Properly?
Frequently asked questions about combining intermittent fasting with a Juice Cleanse
Does juice break intermittent fasting?
Yes, strictly speaking, because juice contains calories. So plan juices as part of your eating window, not as a drink during the fasting period.
How many juices a day make sense on a half-day Juice Cleanse?
As an everyday plan, two to three juices at breakfast are typical. The brand's full Juice Cleanse consists of six juices per day.
How many calories does a cleanse day have?
Depending on the variant, the cleanse days of the 3-, 5- and 7-day cleanses come to 934 (Starter), 799 (Medium) and 680 kcal (Pro).
Can I lose weight with it?
A calorie deficit can lower your weight, but it's not a guarantee. Cochrane sees no clear weight advantage for intermittent fasting.
Who should skip it?
Pregnant and breastfeeding women, children, people with a weakened immune system and people with eating disorders. If you have diabetes or take medication, please check with your doctor first.
Note: This article is for general information and does not replace medical or therapeutic advice. If you have symptoms or pre-existing conditions, are pregnant or take medication, please speak to your doctor first.
