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Juice cleansing: everything a doctor wants you to know

How to juice cleanse safely and if you can when you're sick

Juice cleanses: whether or not you're converted to the supposed benefits of ditching food for days on end, in exchange for liquid fruit and veg, one thing that's for certain is our fascination with them. We grilled Dr Andrew Thornber, Chief Medical Officer at Now Patient, with over 20 years experience, as to whether or not going on a juice detox diet is really a good – or safe – idea, and if it's a successful way to lose weight. Plus, we put a PRESS London package to the test ourselves. Here's what we discovered...

What is a juice cleanse?

A juice cleanse is where a person commits to not eating solid food for a day, or multiple days, at a time in order to gain supposed health benefits – your calorie intake will be well below the Recommended Daily Allowance, too. PRESS London say their juice cleanses are a great way to break bad eating habits and kickstart a healthier lifestyle, while boosting energy levels, skin and offering positive weight loss for some. "We believe they're the perfect reset and chance to flood the body with nutrients," says George Phillips, Operations Manager at PRESS London.

"Many detox or juice diets are also based on the idea that toxins build up in the body and can be removed by eating, or not eating, certain things," explains Dr Thornber. "However, while there's no evidence that toxins build up in our bodies, juices could help improve digestion by introducing healthy enzymes that make the gut work more efficiently." He says they're safe to do for a day or two, but he doesn't advise sacrificing solid food for any longer than that.


Fresh juice cleanse detox

And the medical verdict on the weight loss front? "Juice diets may lead to short-term weight loss, but by restricting calories you’re limiting certain nutrients, which isn’t good for your health. They are basically like a short term fast," says Dr Thornber, whilst stressing that those with kidney disorders ought to steer clear of drinking large quantities of juice, as they may contain oxalate (an acid that can contribute to kidney stones and other problems).

How long should you go on a juice cleanse for?

While many juice cleanse companies sell packages ranging from one day up to a week, Dr Thornber advises no more than two days (and if you have any concerns at all, consulting your own GP beforehand).

Will juice cleansing help when you're sick?

It's probably not a good idea to do a cleanse when you’re ill. "Your body needs all its energy to heal itself and a cleanse doesn’t do this," explains Dr Thornber. "If you do, it could take longer to recover, leaving you feeling sluggish and tired."

Both Dr Thornber and PRESS London say that gentle exercise is okay, but taking a HIIT class mid-cleanse is not advisable. "Exercise can kickstart the natural detox process as it flushes out the lungs and cleanses the skin as we work up a sweat," says Dr Thornber. "Swap running for a low impact walk and take it easier in the gym than you usually would. However, if at any point you feel dizzy or weak, listen to your body and stop." Noted.

Juice cleanse

Can juice cleanses help IBS or any other conditions?

The jury's still out on that one. "There's some debate as to whether going on a juice diet would exasperate or help IBS, it depends on what the individual person has issues with consuming and avoiding foods which may irritate, for example cucumber," says Dr Thornber. It's worth noting that cucumber features prominently in many juice cleanse packages.

So what's a juice cleanse really like to do?


We tried PRESS London's Softcore Juice Cleanse Package

Okay, so I need to begin with a disclaimer – originally I was kindly provided with a three-day package (equal to 709 calories per day and worth £147 in total) to put to the test. However, on what ought to have been Day 1, I caved at 3pm and ordered an Indian takeaway because I was off sick, feeling very sorry for myself and I knew for sure that samosas and dahl were what my body needed. Wow, feels good to be honest. Thanks, guys. So, here's the review of the two days worth of juice cleansing that I did religiously stick to, equating to six bottles of juice and two nut milks per day. The two-day Softcore Juice Cleanse package costs £98 and for a smaller one-day package, you're looking at £49.


Press London juice cleanse detox review
The inside of my fully-stocked, juice cleanse-ready fridge. Former diet seen below.


Having finally recovered from the lurgy, I was excited to get a serious vitamin hit in and begin the cleanse. Using the handy guide that accompanies the juice delivery, I started the morning off with a Wake Up celery juice, before moving swiftly on to some Easy Greens an hour or so later. Both tasted great and by the time my Cacao Nut M*lk was due at 11am, I wasn't even hungry. Ha, juicing! I thought. I could do this in my sleep.

By 1.30pm, things had changed. I was ravenous. Light-headed. The headache was diabolically real. I was hallucinating garlic bread and oh, butter. Sweet, creamy, buttery toast. My desk suddenly resembled a gigantic Pop Tart. I ploughed on and went to bed miserable but determined to continue.

Press London juice cleanse review
The booklet that arrives with all PRESS London packages, suggesting a schedule of when to drink each product.


A miracle! I woke up feeling normal – the crippling headache had vanished – and incredibly, I wasn't bloated (as I often am). Heading into the office, I found it easy to resist the ever-permanent chocolate, biscuits and cheese puffs on offer, preferring my juices and nut milks. Again, they all tasted great. It was fairly easy getting through the day knowing the end was in sight, but by 9pm I was hungry and desperate for solid food once more. I also added up my sugar intake per day on the cleanse, and realised that it rocketed to a huge 114.9g a day... far more than the recommended 27g for women. Gulp.

When I asked PRESS London about this, they said, "The higher natural sugar content is important to maintain energy levels, as while on the Softcore Juice Cleanse package your body is in a calorie deficit. Given the short term length of a cleanse the added sugar won't have a detrimental effect on the body."


Juice cleansing: everything a doctor wants you to know

Overall, I'd rate the two-day cleanse as a 5 out of 10 in terms of required willpower, keeping in mind that my usual diet is fairly healthy-ish, and lost a total of 3.25lbs throughout the process (most of which reappeared after a few days of eating normal-sized portions). I liked the challenge of the experience and can't rate the taste factor of PRESS London's offerings highly enough, but I think if I were to do another cleanse in future that I'd prefer one of their offerings which include soup, to try and stave off some of those intense food cravings.

I can see that a juice cleanse could be a good way to wean yourself off of gigantic portion sizes if that's something you struggle with, but as Dr Thornber said, it's probably best to check with your GP first.

For more information on PRESS London's juice cleanse packages, click right here.

Dr Andrew Thornber is Chief Medical Officer at Now Patient.


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