JUICING fasts are all the rage nowadays. Celebrities such as Rosie Huntington-Whiteley attribute their perfect figures to pulverised vegetables, and sales of juicers have gone up 4000 per cent in Lakeland.

The documentary film Fat Sick And Nearly Dead, in which Joe Cross transforms himself from an obese Aussie bloke (not unlike your stereotypical Scottish equivalent) into a gym bunny by simply drinking juice, was so popular they have made a sequel – yes, Fat Sick And Nearly Dead 2.

I usually watch these sort of developments with a mixture of disbelief and scorn. But then a press release came across my desk about the first juicing detox in Scotland. I had indulged in the usual festive activities, followed by winter hibernation and was feeling a little sluggish. Summer was approaching and I couldn’t fit into my favourite shorts, so I decided why not give it a go?

So how did I get on? Here's an extract from my diary ...

Saturday

As a journalist – and a worrier – I decide to have one last check to see if a juicing fast is actually going to be good for me. I discover that Gwyneth Paltrow had “hallucinations” while only drinking juice. If Gwynnie can’t take it, how am I (an ordinary human being who regularly eats bread and sugar and other "poisons") going to take it?

I arrive at the retreat late on Saturday night after a long drive and too many sweeties feeling a little grumpy.

However, I am reassured by a group of pleasant, well-educated women sharing the retreat, that they are all a little nervous too, and make a conscious effort to be more open-minded.

Over pumpkin soup, Katrina Mather, who set up the Body retreat, expounds the benefits of a juicing fast. She explains that extracting the juice from fruits and vegetables, while discarding the fibre, allows the nutrients to go straight into your system and gives your body a rest from digestion.

I am aware that the body naturally "detoxes" all the time and that depriving yourself of food for a long period is bad for you.

But I am reassured that the juices provided will give us all the vitamins and minerals we need – and even protein from hemp powder. Participants will be given juice three times a day – at breakfast, lunch and teatime – and have a soup in the evening. If we feel we need to eat we can have emergency food like a banana or a cereal bar.

I conclude that my body will certainly be "flooded" with nutrients and fewer calories will be no bad thing for a week. Also, keeping off salt, sugar and caffeine will be a detox in itself.

Sunday

I wake up to the most stunning surroundings. Garmoran Square, where we are staying, looks out onto Loch Shiel and across to Ben Resipol. We all have our own rooms with ensuite bathrooms and there is a shared lounge to chill out and enjoy the view.

The first juice is delicious and includes pineapple, avocado, broccoli and apple. We are encouraged to "chew" the juice rather than gulp it down, in order to "trick" the mind and body we are eating. It sounds ridiculous but certainly, sipping the juice slowly helps to make it feel like a meal.

We set off for a walk to the gorgeous Castle Tioram and Katrina Mather tells me her own story. She suffered from a number of health complaints growing up, including acne, depression and lack of confidence. It was only after discovering juicing that she felt her energy return and the pain lifted.

After a degree in engineering and working in Mexico, she decided to follow her real passion and try and help other people lead more healthy lives through juicing.

Although Mather has been on a number of retreats herself, she eschews extreme "bootcamps" where clients are fed pure cabbage juice and ordered to do a number of work-outs.

Instead, she believes in long walks, a calm environment and simply being in the fresh air and peace of the Scottish Highlands.

She is certainly an inspiration for her retreats, full of energy and looking great. But she also has a light touch, never pushing anyone to accept her theories or make themselves uncomfortable. She takes my cynicism with a smile and allows plenty of time alone.

Monday

Mather warns us we may feel tired and get headaches at the start but I am feeling fine. I take the opportunity of being in a quiet atmosphere to catch up on some work and even go for a run.

Tuesday

I’m still not hungry. How is this even possible? I conclude it must because I'm in a calm, clean place with no temptation around us. It makes it a lot easier not to crave food when you can’t see any and we all make a pact not to discuss baked potatoes and the like – although there are a few covert conversations about the first proper meal.

Wednesday

OK, serious blood sugar low. I have to keep away from other people. Otherwise I may punch someone in the face.

I am over-juicing. Rosie Huntington-Whiteley does not look like Jessica Rabbit because of juicing, she looks like that because of her genes and because she goes to the gym ... and also perhaps because she occasionally drinks juice.

I am finding some of the more alternative messages on the retreat a little hard to stomach, such as the theory that standing on the earth with bare feet can increase blood flow.

Then despite myself, I find that I am standing on the lawn to "earth" myself ... and that it is strangely satisfying.

Thursday

The hunger has passed and suddenly I feel full of energy. The bags under my eyes have reduced and I enjoy walks to the Singing Sands and along Loch Shiel.

Friday

On the last day, we all agree we are looking and feeling better. Mather gives us recipes for juice to take away and lots of tips on how to introduce more raw fruit and vegetables into our lives.

I don’t like weighing myself but as soon as I get home I do try on my summer shorts and I am gratified to find they fit.

Saturday

Ignoring all Katrina Mather’s advice I go out until 4am but in a way it’s a reflection of how great I feel – and Mather's hands-off attitude, which encourages you to have fun occasionally as long as you are sensible most of the time.

The rest of my life ...

After returning home, I bought a cheap juicer and over the next couple of months have had the occasional juice. I am eating more healthily and the weight stays off.

I have to admit that after three months the juices are more like once a week and many bad habits have returned. But here’s the thing: I have retained the high I felt leaving Garmoran Square. I am aware much of it was because of a simple rest in the peace of the Highlands and the advice given by Katrina Mather was mostly just common sense, but in our hurried modern lives sometimes a reminder is all we need.

Prices for a Highland Detox retreat start from £849 per person or £769 sharing. To find out more go to: thebodytoolkit.com