Going on a juice cleanse might sound appealing (if difficult).

[Read more: Are juice or shake diets really good for your health? What you need to know]

Not only do you lose weight, but buzzwords such as ‘detox’ and ‘toxins’ and ‘purify’ and ‘cleanse’ make you feel you are on the righteous path towards clean good health.

With celebs like Rosie Huntington-Whiteley and Lea Michelle looking superbly gorgeous while sipping on their green drinks, why would you think otherwise?

Yes, there are health benefits of drinking freshly-made vegetable or fruit juice, but relying solely on it as your source of nutrition for a prolonged period of time (say a week or longer) might be doing more harm than you think.

Here’s what some experts say is happening to your body if you live solely on juice for an extended period.

1. A juice cleanse isn’t actually helping your body with detoxing

Harmful things that happen to your body when you go on a juice cleanse
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“The idea of a ‘detox’ diet is to rid our bodies of any stored up toxins, but the truth is that toxins do not build up for a harmful length of time if our organs are doing their job properly,” says Emma Brown, who has an MSc in Human Nutrition.

“Our liver, kidneys, digestive system and skin are a natural defence against anything harmful such as infection, drugs, bacteria, metabolic waste products and exogenous chemicals such as pesticides, and these systems work around the clock to remove anything harmful from the body as quickly as possible.”

So basically, going on a juice cleanse for a week isn’t really doing anything that your body isn’t capable of doing on its own.

2. In fact, it might just hinder the detoxing process

“There is no scientific evidence to support claims that juice cleanses help to aid the body’s natural detox systems – in actual fact, it could hinder it,” says Brown.

“Because juice diets are very limited, they remove fibre and protein from our diets for a short while – both of which are important for the body’s natural processes.

“Protein is needed for the normal functioning of the liver, and fibre is important for keeping the digestive system ticking over smoothly. Remove these from our diet and processes can be disrupted.”

3. Your skin might dry up

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Here’s the thing. You might have read that a juice detox will result in a glowing healthy skin, but that’s not always the case (unless of course you’ve been eating huge amounts of junk food and have taken up juicing as part of your health kick).

Also, when you eat a low calorie diet, you use up water that is stored in your muscles with glycogen, causing your skin to feel dry.

“Balance is the key,” says Antonia Burrell, associate lecturer in the chemistry of aromatherapy at the London College of Fashion. “If someone is doing a juice fast then prolonging this can lead to a drier skin and potentially a prematurely ageing skin because of the lack of essential fatty acids being consumed.”

4. You will starve your body of vital nutrients

Harmful things that happen to your body when you go on a juice cleanse
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“Juice detoxes tend to only include fruit and veg, meaning they lack important nutrients such as protein, calcium and fibre,” says Brown.

“Protein is important for muscle repair, immune functions and metabolic processes, calcium is important for bone health and fibre is important for the healthy functioning of our bowels.

“Fibre, essential amino acids and good fats are very important for the correct functioning of our body’s internal processes.

“Removing these from our diet will mean our body is deprived of the important vitamins, minerals and nutrients it needs to function correctly and healthily.”

5. Removing fat from your diet means some vitamins can’t be absorbed into your body

A juice cleanse eliminates the possibility of eating fat altogether. But is that really a good thing?

“Good fats are very important for the correct functioning of our body’s internal processes. Removing these from the diet can mean the body can’t perform at its optimum level,” says Brown.

“For example, fat soluble vitamins A, D, K and E require fats in the diet in order to be absorbed.

“If your diet does not include some fat, the uptake of these vitamins from food will be limited.”

6. You could be damaging your teeth

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Juices, especially fruit juices, not only damage your teeth, they aren’t good for your gums either.

“Diets like juice cleanse can cause insulin levels to peak and then plummet. Over time, this alters the structure of collagen in the body and therefore affects your gums – as it’s collagen fibres that hold your teeth in place,” says Dr Sameer Patel, clinical director at Elleven.

“Not only that, the juice from fruit and vegetables, especially fruit, tend to have a high acid content which severely damages the enamel of your teeth in a similar way to fizzy drinks.

“Although fruit and vegetables are considered healthy acids, this is only the case when they are consumed as a whole, rather than as a concentrated juice.

“Ultimately this can lead to teeth sensitivity as the protective layer of enamel is worn down and eroded by the juice.”

7. You might end up feeling more stressed

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“There are possible benefits of juice detox, that include feeling ‘lighter’ and more energised,” says Cassandra Barns, nutritionist at NutriCentre.

“But in terms of downsides, some people may feel hungry and perhaps have a headache or feel irritable during the first day or two.

“Fasting for long periods of time is not recommended as it can stress your body and cause the breakdown of muscle.

“People who have done a juice fast have experienced some form of fatigue, dizziness, constipation and even dehydration.

“These symptoms could be from having low blood sugar levels, being dehydrated and having withdrawals from caffeine and other foods such that your body may have got used to having.”

8. You won’t be able to keep up with your exercise

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Tiredness and fatigue is not what you want when you head over to the gym – and if you are surviving solely on fruit and veg juices, you won’t be able to perform at your optimum best.

“If someone were to start juicing without eating any solid food, this could impact on exercise or training,” says Dr Sam Christie, a nutritionist at Nature’s Best.

“Anyone training or engaging in vigorous, prolonged or demanding exercise should ensure that their calorie intake is adequate to fuel it and extra water is consumed, as juices are concentrated and may not adequately hydrate your body.

“If not, they will feel fatigued and lacking in energy, which of course could adversely affect performance.”

9. You will be less tolerant to cold temperatures

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Warm foods and drinks can keep help you maintain your body temperatures during the winter months, so going on a juice fast in the middle of winter might not be the best thing to do, if you aren’t keen on freezing temperatures.

“Not having warm food can also make you feel cold,” says Barns.

10. It can hamper your digestion and make you bloat

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Fibre is an important part of a healthy diet and the NHS recommends having 14g of fibre a day for good digestive health.

But when you put your vegetables through a juicer you end up breaking down all that health-boosting fibre onto a liquid pulp.

Not only that, fruit juices tend to contain a lot of natural sugar, which the bad bacteria in our gut feed on.

“This disturbs efficient elimination and toxins can even get reabsorbed into the bloodstream,” says Ernesta Stripeikaite, Fushi’s naturopath and wellbeing expert.

“A common side effect of juice cleansing is something called SIBO – small intestinal bacterial overgrowth, which can result in bloating and indigestion.”

11. You might end up on a high-sugar diet

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Fruit juices is a concentrated source of natural sugars – a result of blitzing them through a blender or juicer where healthy fibres are broken down.

If you consume it without any other food, juice passes relatively quickly through your stomach to your small intestine, where the both the nutrients and the sugar are rapidly absorbed.

“For individuals with diabetes and other forms of ill-health juice cleansing diets are positively NOT recommended because of the additional ‘free sugar’ produced during the process,” says Dr Christie.

12. You may lose weight but will affect your metabolism

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“Extreme calorie reduction like this means your body starts to use energy from other sources – but not only from your fat stores, but also protein from muscle mass too – which is not good!” says Brown.

“Muscle is important for maintaining a healthy metabolic rate as it is a metabolically active tissue. Losing muscle mass can impact on your metabolism longer term.”

13. Your hair might fall out

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When your body doesn’t get the nutrition it needs, survival mode kicks in and it focuses on the organs that are essential to life. And one of the things that get affected is hair production and hair growth.

“Limiting the diet to just juices means your body may be missing out on nutrients such as fibre, calcium and iron as well as protein and healthy fats – which are incredibly important for hair health,” says TV nutritionist Charlotte Stirling Reid.

So what’s the verdict?

“Aside from it being healthy or unhealthy – juice cleansing is entirely unnecessary,” says Brown.

“While not eating solid foods for just a few days will not do you any long-term harm, it certainly won’t achieve much.

“The very low calorie intake may result in some weight loss, but cutting out complete food groups and following a very low calorie diet for more than a few days is not advised as the lack of essential nutrients can have an negative impact on health.”

And if you still want to go ahead with a cleanse…

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1. “You should not fast if you are pregnant or breast feeding or if you have a medical condition that means you have to eat regularly such as diabetes,” says Barns.

2. Stick to between 1 and 3 days duration unless you are working with a nutritionist or other health practitioner.

3. If fruits are juiced together with vegetables, you can add some of the pulp back into the juice so you don’t miss out on the fibre.

4.  Drink with a straw to avoid acidic fruit juice to come in contact with your teeth.

5. Go for vegetable juice over fruit to minimise your ‘natural sugar’ intake.

6. Or, instead of a juice-only cleanse include juices as part of your balanced diet, rather than a substitute for solids.