Those trendy juice-only crash diets can damage your health

a bikini and my diet had the required result,’ she says.

Since then, she has been on seven more juice diets, all lasting between three days and a fortnight. ‘My favourite juice is cucumber, celery and apple,’ says Kelly, who is planning her next juice diet before a friend’s wedding.

‘Mint gives my juices a kick and if I want a treat I’ll have pineapple and orange. I’ve also juiced onions and garlic as I read it could ease cold symptoms — which it did — and drank kale juice for three days to boost my iron levels.’

But within a couple of months of eating normally, the weight always returns. And though Kelly insists she does not feel hungry — even when juicing for a fortnight before a holiday to Cyprus last summer, during which time she lost 1st — she admits there are downsides, not least the £70 a week cost. ‘Because the juicers extract the pulp of the food, you need to buy a lot of fruit and vegetables to make enough liquid, which makes me feel guilty,’ she says.

‘Liam is supportive, but the diet is isolating. And after a week without solids I forget how to chew. When I try to eat, the food goes everywhere like a baby.’ But detox diets can have far more serious consequences. In January, the British Medical Journal reported that a 47-year-old woman had been hospitalised after following a liquid ‘detox’ diet.

The combination of excessive water intake plus the effects of a herbal remedy called valerian root, which she also took, is thought to have caused dangerously low sodium levels, leading to lifethreatening seizures.

CLAre McCArTNeY says following liquid diets for the past 14 years has dried out her skin, given her migraines and even caused her to faint.

Yet astonishingly, she continues to survive on only juice for at least one day a week.

‘I know they can be bad for me, but I find them addictive,’ says Clare, 42, from Harlow, essex, who has kale, spinach and ginger juice for breakfast and lunch followed by a carrot and spinach concoction for dinner.

Clare, who had a hectic career at a computer training company, went on her first juice diet at a yoga retreat in the U.S. in 2003, aged 28, during which she drank nothing but carrot, spinach and ginger juice for three days.

‘The instructor said it would cleanse our minds and bodies,’ she says. ‘After day one I got a migraine — my first ever — but by day three my clothes were looser. I was feeling healthier and more in control than I had in years. I was hooked.’

Back home, she bought a juicer and alternated a reasonably healthy diet with living on fruit and vegetable juice for three days a week at least twice a month — a practice she has continued for the past ten years. She also retrained as a yoga teacher.

Alongside her three replacement meal drinks, Clare usually has two daily ‘treat’ juices containing pineapple, orange and banana on her liquid diet. She consumes a total of 20 pieces of fruit and vegetables — which rarely amounts to more than 800 calories — a day.

Over the years her juicing has been so fanatical her neighbours have complained about the noise coming from the machine. On one occasion, her juicer was broken by an endless barrage of carrots.

And though Clare — 5ft, 8st 2lb and a size ten — insists she started liquid diets to feel healthier as much as to lose weight, the 5lb she typically loses after three days were nonetheless welcome.

‘I loved the way my stomach looked flatter afterwards in a way it never did when I’d tried to cut down on solid food,’ she says.

‘I enjoyed fitting into size eight dresses and eating my favourite meals when I wasn’t juicing without feeling guilty.’

She insists juices fill her up, but admits: ‘After three days I feel weak, wobbly and irritable. Once I fainted in front of my boss, who sent me home. I was too embarrassed to tell why I’d fainted.

‘I often suffer migraines. My skin develops dry patches and my mum and friends say liquid diets are incredibly bad for me.’

Two years ago, she decided they might have a point.

‘I was constantly exhausted and the weight loss had slowed — I think my body conserved calories in anticipation and I lost only 2lb.

‘I decided that, on a regular basis, I would drink juice only for one day a week.’ Now she does juice-only Thursdays before a weekend indulging in roast dinners and fajitas, quickly putting on the pound or two she lost. You can’t help but suspect the deprivation drives her to eat more, especially as even Clare admits: ‘It would probably be better for me to just eat healthily all the time.’ L ydia Wheatley believes liquid diets are the most effective way for her to ‘fine tune’ her body. She survived on liquids only for eight weeks in November 2015 to slim down to a size ten for a spate of parties. Lydia, 37, a mother of three from Croydon, Surrey, who edits a parenting magazine, says: ‘I wanted to achieve a flat stomach and reduce the fat on the back of my arms. ‘I had heard that Beyonce had done liquid diets to prepare for film roles and was intrigued. ‘I’d tried cutting down on carbs and controlling my portion sizes before, but had never lost any weight. Solid food, especially bread, made me bloated and I’m so busy that I rarely have time to prepare healthy meals.’ Lydia, 5ft 6in and formerly 10st, devised her own 1,500 calorie-aday diet, with porridge made from a couple of tablespoons of cornmeal for breakfast, a fruit and yoghurt smoothie for lunch and a liquidised vegetable soup for dinner. ‘I added almonds and avocados to my smoothies for protein. I certainly wasn’t starving myself and used a blender that kept the pulp of the fruit and vegetables so I got enough fibre,’ says Lydia.

BUT, again, says dietitian Anna Daniels: ‘Any kind of liquid diet is unsustainable and doesn’t teach long-term healthy eating habits.’ Certainly, Lydia seems to have approached what she describes as her ‘challenge’ as a test of mental fortitude.

‘I had to stop socialising as I love food and would have found it hard to resist a deep-fried prawn in a restaurant,’ she says.

‘I had to have my liquid meals separately from the children, whose chicken and pizza would have been all too tempting. But I would have felt worse should I have quit.’

After a week she had lost 3lb. After eight weeks she had shed a stone to become 9st and size ten.

‘My stomach was flatter, my arms looked tighter and I felt I had flushed the toxins out of my body,’ she says. And though the weight crept back on, Lydia went on another liquid diet last summer in preparation for a party.

This time her 1,000 calories-a-day diet comprised protein shakes, honey and water, and coconut water and yoghurt smoothies.

‘For the first three days I missed food, but then I felt good,’ says Lydia. She lost 6lb in seven days and celebrated at the party by wearing a long, figure-hugging ball gown while tucking into the evening buffet with abandon because, she says: ‘If I’ve achieved my goal I should be rewarded.’

Nonetheless, she has managed to maintain her weight loss since then by replacing one or two meals with drinks every day.

‘If I do put on weight I won’t hesitate to go on another liquidonly diet,’ she says. ‘For me, it’s the most effective way of looking good and losing weight.’