Detox Diets and Juice Cleanses: What They Do and Do Not Do
Detox diets and juice cleanses do not remove toxins that your body would otherwise keep. In a healthy person, the liver, kidneys, gut, lungs and skin already process and clear waste continuously, and no juice, tea or powder has been shown to improve on that. What a cleanse does do is cut your calories sharply for a few days, reduce salt, alcohol and processed food, and drop some water and gut content. That is why the scales move and you may feel lighter. Most of it returns within days of eating normally, and you lose muscle-friendly protein in the meantime. The benefit people actually feel usually comes from what they stopped eating and drinking, which you can do without the juice.
Here is what is going on in more detail, and what I suggest to clients who come to me after a cleanse.
Why people try them
Usually for understandable reasons. After Christmas, a holiday or a run of client dinners, people feel heavy, bloated and sluggish, and want a reset. A cleanse offers a clear start and finish, simple rules and the sense of doing something decisive. I do not dismiss that impulse. The problem is the method, not the motive.
What “toxins” means, and what clears them
Detox products rarely name the toxins they claim to remove, which is telling. In medicine, detoxification refers to things like treating alcohol or drug dependence, or poisoning, and it happens in hospital. For everyday waste products and things like alcohol, your body has dedicated systems:
- The liver breaks down alcohol, medicines and metabolic by-products.
- The kidneys filter the blood and remove waste in urine.
- The gut moves out what is not absorbed, helped by fibre.
- The lungs clear carbon dioxide.
If these organs are not working properly, that is a medical problem that needs a doctor, not a cleanse.
Why the scales drop on a cleanse
A three-day juice cleanse might show a noticeable drop on the scales. Very little of that is fat. Most comes from:
- Stored carbohydrate and water. When you eat much less, your body uses stored glycogen, which is held with water. That water goes with it.
- Less food in the gut. Juice leaves little bulk behind.
- Less salt. Lower salt intake means less water retention.
All three return when you eat normally again. This is the difference between weight loss and fat loss, and it is why the post-cleanse rebound feels so discouraging.
The costs people do not notice
- Very little protein. Fruit and vegetable juices contain almost none. A few days is not dangerous for most healthy people, but repeated cleanses work against keeping muscle.
- Lots of sugar, little fibre. Juicing removes most of the fibre and concentrates the sugar. The NHS Eatwell Guide suggests limiting fruit juice and smoothies to a combined 150ml a day for this reason.
- Poor training. Low energy, headaches and irritability are common. Sessions in the studio during a cleanse are rarely good ones.
- Detox teas. Many contain laxatives or diuretics. They make you lose water and spend time in the bathroom, which is not fat loss and can be unpleasant or risky with regular use.
- Price. Ready-made cleanse programmes are expensive for what is, nutritionally, a few days of fruit and vegetables without the fibre.
Who should not do one
Check with your GP before any very low calorie or restrictive diet if you have diabetes, kidney or liver disease, any other ongoing medical condition, take regular medication, are pregnant or breastfeeding, or have a history of disordered eating. Grapefruit juice in particular interacts with a number of medicines.
What works instead: a sensible reset
If you want the clean start feeling without the rebound, a structured week of ordinary food does the job better. This is the version I give clients:
| Instead of | Do this for a week |
|---|---|
| Juice only | Three meals built around protein, vegetables and some whole grains |
| Detox tea | Water, plain tea and coffee as usual |
| Cutting all solid food | Cutting alcohol for seven days |
| Skipping training to “rest the body” | Two strength sessions and a daily walk |
| Supplements | An earlier bedtime most nights |
Most people feel noticeably better within a few days because of what they removed: alcohol, late-night snacking, large restaurant portions and high-salt food. Alcohol in particular is worth looking at honestly. Our piece on alcohol and fat loss covers how to keep it without stalling progress.
What about juice as part of a normal diet?
Nothing wrong with a small glass with breakfast. The issue is drinking a lot of it, because juice is easy to overconsume compared with whole fruit. If you like it, keep it to a small glass and eat whole fruit the rest of the time. Smoothies that keep the whole fruit are better than juice for fibre, but still count towards the daily limit. The guide to liquid calories has more on this.
After a cleanse: getting back on track
If you have just finished one, do not panic when the weight comes back. That is water and food, not failure. Eat normal, protein-rich meals, start training again at a comfortable level, and judge progress over weeks rather than days. If you train with me, this is where the InBody scanner helps: it gives a clearer picture of muscle and fat over time than the bathroom scales alone.
The personal training in Highgate I run is built around exactly this kind of steady change: two or three sessions a week, practical food guidance, and progress you can keep.
Questions we get asked
Is a juice cleanse dangerous?
For most healthy adults, a few days is unlikely to cause harm, but it is not useful either. It is a different story if you have a medical condition, take medication or are pregnant. Speak to your GP first.
Does detox tea work for weight loss?
Many work by making you lose water through laxative or diuretic ingredients. That is not fat loss and returns quickly.
Can I train during a cleanse?
Light activity, yes. Hard sessions on very little food tend to feel poor and recover badly. I would rather you ate properly and trained well.
How much does personal training cost?
Current prices are listed on the personal training page, along with how sessions are structured.
Book with The Highgate House
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