I never thought I'd drink a cabbage. But here I am, sitting in a sun-cooked garden on the Algarve with a green moustache and an empty pint glass. When I flew to Portugal for this seven-day raw juice camp (run by British company Explore Raw) I was overweight and newly single. I felt rather like the eponymous chronometer of the nursery rhyme My Grandfather's Clock: too large for the shelf. But I had heard impressive stories about the benefits of juicing, and if the alternative was "90 years on the floor", it had to be worth a try.
If the tabloids are to be believed, raw juicing is the method du jour for celebrity weight loss, with acolytes including Beyoncé, Woody Harrelson and Jennifer Aniston. The science is simple: raw foods contain more vitamins and minerals than their cooked counterparts, and juicing them (skin and all: that's where a lot of the good stuff hides) is the fastest, most efficient way to inject those benefits straight into your system. If you shove the correct ingredients into your juicer, you'll have all the nourishment you need and more – within seconds.
When it comes to retreats, juicing is already a crowded bandwagon, with laughably expensive tickets – particularly given that you're not paying for "food" in the traditional sense of the word. But Explore Raw is dedicated to changing that. Founder Stephanie Jeffs, a 43-year-old former City worker who says she shed nine stone and cured her polycystic ovary syndrome after discovering juicing – offers weekly breaks at a villa in Vale de Lobo near Faro from as little as £500.
For that price you have to camp, but that's no great hardship in the property's beautiful gardens, with a state-of-the-art solar-powered shower, inflatable beds and an option for ready-pitched tents. (For juicers with more liquid assets rooms are available in the house itself.) After three days of just juice (enough to cleanse away baddies such as sugar and caffeine), small meals of raw food are added to your newly cleansed system. These, like the juices, are 100% vegan and served at room temperature. Then there's the "compulsory" exercise. We have three training sessions a day, guided by affable former soldier Damien, who likes sweat – a lot. ("It's fat crying on its way out of your body, mate.")
The first three days on just juice are hard. By day two, conversation within our 10-strong group (80% female; 80% British; 80% aged 25-45), has turned almost exclusively to food: roast lamb; pizza; stilton cheese. When we're not exercising, we're fantasising about food. On the third day we drive to a farm to pick oranges for our juices and, when Stephanie's back is turned, I grab a handful of parsley from the herb garden and chew it, stalks protruding from my mouth, like a famished goat.
The juices themselves are as full of flavour as they are of vitamins, with ingredients as diverse as lemon, kale, cacao nibs, spinach, cauliflower and avocado. I know I'm getting enough nutrients but my body – or rather, my mind – really misses the act of eating. When we're finally given a tiny portion of food (a simple carrot and seed concoction), I wolf it down like an Alsatian eating a bowl of chicken.
The villa is 15 minutes' drive from Faro airport in an area popular with golfers and, recently, England's football team in training. But it's also an easy jog to picturesque Trafal beach, where we run every morning.
The sense of calm and relaxation is reinforced by scheduled midday naps, ever-present sunshine and group film screenings every evening. By the end of the week, I've lost 11cm off my waist, 8cm off my hips and my shorts (once, when diving into the pool). But it's what I've gained that's more significant. My skin is glowing, my eyes seem whiter, and I have a ridiculous overabundance of energy. I feel like a superhero (Cabbage Man? Avocado Boy? ). It sounds strange, but just a week of ingesting nothing but raw fruit and vegetables has made me feel capable of anything as I head home. And that's the raw truth.
• Accommodation was provided by Explore Raw (07914 399 109, exploreraw.com), which runs week-long boot camps from £500, not including flights. The next camps in the Algarve will run 27 September-4 October and 4-11 October. Easyjet (easyjet.com) flies to Faro from seven British airports from about £60 return
