Juice cleanse: the complete guide to choosing, preparing and doing a juice cleanse
Juice cleanses are having a real moment. On social media as much as on supermarket shelves, it's hard to escape the colourful bottles promising to "cleanse", "purify" or "detoxify" the body in just a few days.
But behind these promises, what actually happens in your body? Is a juice cleanse useful? Dangerous? Effective for weight loss? And above all: how do you tell a good cleanse apart from a simple marketing gimmick?
This guide isn't here to sell you a miracle promise.
It's here to give you honest information, so you can decide for yourself, with a clear picture, whether a juice cleanse has a place in your routine — and how to get the most out of it.
What exactly is a juice cleanse?
A juice cleanse involves replacing part or all of your diet, for a short period (generally 1 to 5 days), with a series of cold-pressed fruit and vegetable juices, consumed at regular intervals throughout the day.
The idea isn't new: it draws on older mono-diet and liquid-cleanse practices, but it has been widely popularised over the past fifteen years by the rise of cold-pressing and "detox" juice brands.
In principle, then, it's neither a full fast nor simply a juice alongside a meal: it's a short, structured pause during which solid food is temporarily set aside.
The word "detox": what you should know before you start
Let's be direct: the term "detox" is, today, more of a marketing argument than a medical reality.
Your body already has its own detoxification organs: the liver, kidneys, lungs, skin, and digestive system.
They work continuously, without needing a particular juice to "switch on".
To date, no serious study has shown that a juice cleanse speeds up or strengthens these natural elimination functions. Several public health and nutrition bodies have reached the same conclusion: there is no reliable scientific evidence that a "detox" diet produces a purifying effect in the medical sense of the term.
The same applies to weight loss: while rapid weight loss is sometimes observed during a cleanse, it most often corresponds to water loss, and sometimes muscle mass — not fat. This weight tends to come back as soon as you resume a normal diet.
At PIMSIE, we would rather be honest with you than sell you a promise that science doesn't support.
A juice cleanse is not a medical treatment, nor a way to "clean" your organs.
So what is a juice cleanse actually good for?
If a juice cleanse isn't a medical detoxification tool, that doesn't mean it has no value at all. Its real benefits are simply different from the ones advertised on the label.
- A concentrated dose of vitamins and minerals from several fruits and vegetables in a single day.
- Good hydration, since juices are largely made up of plant-based water.
- A psychological reset after a period of excess (holidays, festivities, a busy stretch), which helps you refocus on simpler, less processed food.
- A gateway to eating fruit and vegetables more regularly, for those who don't get enough of them day to day.
These are real benefits, but modest ones, and above all temporary. A juice cleanse only makes sense as part of an overall balanced diet before and after — not as a standalone fix meant to "undo" poor habits built up over months.
Juice versus whole fruit: a difference worth knowing before you start
One point deserves to be stated honestly, as it changes how you should approach a juice cleanse: drinking a fruit or vegetable is not the same as eating it.
During pressing, most of the fibre is removed. Yet it's precisely this fibre that slows down sugar absorption and extends the feeling of fullness. A juice, even freshly pressed with no added sugar, therefore naturally has a faster impact on blood sugar than a whole fruit eaten as is.
This is why a juice cleanse isn't designed to replace whole fruit and vegetables on a daily basis.
It's designed as an occasional pause, not as a permanent way of eating.
This is also why the composition of a juice matters enormously: a blend made mostly of low-sugar green vegetables (cucumber, celery, spinach, kale) has a very different impact on blood sugar than a juice made almost entirely of fruit or apple juice.
Not all juice cleanses are equal
As with any single juice, not all the juices used in a cleanse come from the same mould. Several factors make a real difference in quality.
1. The extraction method
A cold-pressed juice, obtained through slow mechanical extraction with no heating, preserves more of the vitamins and enzymes sensitive to temperature than a juice made with a high-speed centrifugal juicer (which slightly heats the juice through friction) or a juice reconstituted from concentrate.
2. Freshness and the time before consumption
Like any fresh product, a juice keeps changing after it's made. A cleanse made up of juices pressed a few days before you drink them, rather than several weeks earlier, retains more of its original nutritional and taste qualities.
3. The balance between fruit and vegetables
A cleanse made purely of fruit juices will be noticeably sweeter than one built mostly around green vegetables. This balance directly affects the energy you feel during the cleanse, as well as any dips in energy or cravings over the course of the day.
4. The quality and origin of the ingredients
Good-quality fruit and vegetables, ideally local and in season, produce a juice richer in flavour and nutrients than ingredients chosen solely for their cost or year-round availability.
Who is a juice cleanse not suited to?
An occasional, well-designed, short juice cleanse generally poses no risk to a healthy adult. However, it's not suited to everyone, and certain situations call for extra caution.
- People with diabetes or difficulty regulating blood sugar, given the impact of juice on blood sugar levels.
- Pregnant or breastfeeding women, whose nutritional needs are increased.
- People with a history of eating disorders, for whom even a temporary restriction of solid food can be delicate.
- Children and teenagers, who are still growing.
- People on medical treatment, particularly for kidney, liver, or digestive conditions.
In all these situations, the advice of a doctor or dietitian is the best guide. A juice cleanse remains a personal, occasional choice — never a prescription.
How to properly prepare for and finish your cleanse
How you approach a juice cleanse often matters more than the cleanse itself.
Before the cleanse
It's generally advisable to gradually cut back, in the days beforehand, on coffee, alcohol, refined sugar, and processed food. This gentle transition limits the headaches or fatigue sometimes felt at the start of a cleanse, which are often linked to abrupt caffeine withdrawal rather than to the cleanse itself.
During the cleanse
Drinking water alongside your juices, listening to your body's signals, and favouring rest over intense physical activity are the most useful habits. Feeling hungry is normal; feeling dizzy, shaky, or unwell is not, and should lead you to stop the cleanse and return to solid food.
After the cleanse
Gradually reintroducing solid food — starting with simple, easily digestible foods (fruit, cooked vegetables, broths) before returning to a full diet — helps avoid the digestive discomfort that a too-abrupt return to heavy meals would cause.
PIMSIE juice cleanses
At PIMSIE, we've built our cleanses with these principles in mind: transparency rather than promises, and quality rather than volume.
- Juices cold-pressed locally, in Linkebeek.
- Cleanses available over 1, 3, or 5 days, to suit your pace and your experience with juice cleanses.
- A thoughtful balance between fruit and vegetables, rather than mostly heavily sweetened juices.
- Fresh ingredients, selected for their quality.
- Fast delivery in and around Brussels, so your juices arrive as fresh as possible.
We won't promise to "cleanse" your body. We offer you a fresh, enjoyable, well-designed pause — it's then up to you to fit it into a diet that works for you over the long term.
Frequently asked questions about juice cleanses
Does a juice cleanse actually detoxify the body?
No, not in the medical sense of the term. The liver, kidneys, and other elimination organs work continuously and don't need a particular juice to be "activated". No serious study shows that a juice cleanse speeds up these natural functions. That said, a cleanse can help you temporarily turn away from processed food and refocus on simpler eating — which is already a real benefit, just a different one from a "detox" effect.
Does a juice cleanse help you lose weight?
Rapid weight loss is sometimes observed during a cleanse, but it generally reflects water loss, not fat loss. This weight most often comes back as soon as you resume a normal diet. A juice cleanse is therefore not a lasting weight-loss solution; at most, it can support a shift towards new long-term eating habits.
How long should a juice cleanse last?
There's no universal length. A one-day cleanse lets you try the experience and take a brief pause. A 3-day cleanse is the most common format for a more noticeable effect. Beyond 5 days, the extended absence of solid food (protein, healthy fats, fibre) becomes harder to balance, and the advice of a health professional is recommended.
Can you exercise during a juice cleanse?
It's generally advisable to favour light physical activity (walking, stretching, gentle yoga) rather than intense training, since calorie and protein intake is reduced during a cleanse. Listening to your body's signs of fatigue remains the best rule.
Is cold-pressed juice the same as whole fruit?
No. Pressing removes most of the fibre from the fruit or vegetable, which speeds up sugar absorption and reduces the feeling of fullness compared with the whole food. This is why a juice cleanse is designed as an occasional pause, not as a permanent substitute for whole fruit and vegetables in your daily diet.
Who should avoid a juice cleanse?
People with diabetes, those who are pregnant or breastfeeding, children, people with a history of eating disorders, as well as anyone on medical treatment, should seek advice from a doctor or dietitian before starting a juice cleanse.
Key takeaways
A juice cleanse is neither a miracle solution nor a medical treatment. It's an occasional tool, provided it's well designed: quality juices, a balance between fruit and vegetables, gradual preparation and reintroduction of food, and close attention to your own body.
A good juice cleanse doesn't promise to transform you.
It simply offers you a fresh pause, so you can head off again with good intentions.
If you'd like to discover our cold-pressed juice cleanses, made locally in Linkebeek and delivered quickly in and around Brussels, we'd be happy to guide you.
Sources and references
This article draws on publications from nutritionists, public health bodies, and scientific journals regarding detox cleanses, fruit and vegetable juices, and their effect on blood sugar.
- Radio-Canada (Mordu) — "detox" juice cleanses: promises and reality, with nutritionist Karine Gravel
- National Center for Complementary and Integrative Health (NIH, United States) — "Detoxes and Cleanses: What You Need To Know"
- Klein, A. V., & Kiat, H. (2015) — Detox diets for toxin elimination and weight management: a critical review of the evidence, Journal of Human Nutrition and Dietetics
- Deutsche Gesellschaft für Ernährung (German Nutrition Society, DGE) — lack of scientific evidence for a purifying effect from detox diets
- Flood-Obbagy, J. E., & Rolls, B. J. (2009) — study comparing satiety from whole fruit versus fruit juice
This article is for informational purposes and is updated regularly. It is not a substitute for personalised medical advice.