Madonna and Gwyneth Paltrow: A-listers, friends and dedicated to the cause of self improvement via some out-there therapies and treatments. Madonna, the world's most famous 50-year-old, doesn't let a little matter like the natural ageing process stand in the way of looking fabulous. Gwyneth, oh she of the endless legs and short, short skirts, does not look like your typical 36-year-old mother of two. But looking this hot requires strict diets, extreme exercise regimes, a lot of time and even more money. Could mere mortals hack the pace? Our two writers try a week of living like Madge and Gwynnie.

Una Mullally gets into the Madge groove for a week

Madonna is psychotic. That's the conclusion I reach after a week in her shoes. Don't believe me? Try a daily dose of ashtanga yoga and pilates, 45 minutes on a stairmaster, weightlifting, a power plate session, swimming and cycling. And that's just the exercise bit. The task of living like Madonna for a week isn't remotely fair, I realise halfway through, because I don't seem to be getting any of the Madonna benefits – a Brazilian model, loads of staff, faffing around the place on yachts, hanging out with David Letterman etc. Instead, I have only the hard bits.

I started off quite well. Of all strict diets, macrobiotic eating is probably the most sensible and most achievable. It's all about balance (yin and yang, but in food terms), avoiding processed food, dairy, fat, sugar and red meat. Mostly, my diet was made up of vegetables (apart from 'nightshades', so no peppers, tomatoes or aubergines, and few potatoes), brown rice, some pulses, and lots of soup. I cut down hugely on red meat and upped my fish intake. I never felt hungry – even though previously my diet was high in pasta, potatoes, bread and other heavy carbs – and by the end of the week felt pretty good.

But of course, I faltered several times. On Wednesday morning, after a gig and two pints of Heineken the previous night, channelling Madonna on tour circa 1991, I sobbed quietly into a breakfast sandwich in the office. Claire aka Gwyneth came over to me. "Wouldn't it be more fun to do the anti-Madonna and Gwynnie piece?" she said. "Isn't that our normal lives?"

After food shame, it was time to take care of the exercise bit of Madge's life. What stunned me about Madonna's exercise regime was how she finds the time. Ashtanga yoga is much more strenuous than normal static yoga and full of complicated postures. I decided to go for Madonna's pilates route. And having never tried it before, attempted self-tutorial (sure, Madonna would be far too important to go to a class with the rest of civilians) by replacing an expert pilates teacher with, um, YouTube videos, I managed to get through five beginner videos over five days without too much stress. After five days of core work, I had sore stomach muscles, my 'core' awakened from years on the couch.

The next stage of exercise was to hop on a power plate. Madonna has one of these vibrating exercising platforms at home. The theory behind it is that because the platform vibrates, it causes involuntary reflex muscle contractions, which tones your body. My personal trainer was an ex-Gladiator, which was encouraging. This was the type of person Madonna would be trained by, I thought to myself wistfully as I sipped a fruit smoothie. And boy, does it work. While doing normal press-ups, crunches and squats, the intensity was amplified by the endless vibrations, making my body work harder. After half an hour I was pooped, but it was quite exhilarating. I was becoming more like Madonna! Neurotic! Steely! Addicted to exercise! Felt very happy with myself.

Next I delved into her Madgesty's spiritual side. I searched far and wide for a Kabbalah group in Dublin, of which there is one, but they weren't meeting up again until 21 October. So I was on my own again. I tried to study some of the main principles of Kabbalah, but instead of finding the wishy washy mysticism I was expecting, it's an extremely complicated set of beliefs that requires a lot of study. It surprised me that Madonna – a woman of such huge self-importance – believes in something bigger than her own existence.

My final stage of transformation was to follow Madonna's beauty regime. This meant Fusion RF, a non-invasive treatment where radio waves are pumped into your face to encourage collagen production, tightening your skin, making it look younger and fresher. Madonna is so into this that a Fusion RF machine comes on tour with her. There's only one place in the country that has a machine to do this, so off I popped to Bellaza beauty salon in Ranelagh, Dublin. Sue Machesney, who was going to make my face Madonna-like, took a 'before' picture, prior to rubbing me almost into submission with a tool which emitted radio waves deep into my skin. Thanks to Sue's safe hands, I lasted the full 40 minutes, and behold, my skin was much tighter. My jaw line was far more defined (even my cynical friends said so), and there seemed to be a piece of fat lobbed off from underneath my chin. Success!

And so the week came to the end. Living like Madonna was extremely testing. I felt hassled nearly every step of the way – what not to eat, when to collapse into a yoga pose, how to look younger, when to exercise and so on. I simply don't know how she does it. It's a superhuman existence based on extreme discipline, and clearly, many, many assistants.

* Live like Madonna

Eat: Macrobiotic diet with organic wine if you must booze. www.organicwinesireland.com

Exercise: Daily doses of Pilates, Astanga yoga, 45 minute stairmaster, weight training, and Power Plate sessions. (www.powerplate.ie)

Drink: Kabbalah water, no caffeine

Beautify: Fusion RF, (Bellaza Beauty Salon, 27 Ranelagh Road, Dublin 6 (bellazabeauty.com ; 01 496 34 84)

Think: Frequent Kabbalah classes

Play: Get a Brazilian boyfriend

Claire O'Mahony channels her inner Gwynnie for a week

While the rest of you civilians have been living your usual toxic lives of quiet desperation, I have been busy being fabulous. This is the week I eliminated a food group called 'nightshades' (tomatoes, chillis, red peppers) from my diet. I regenerated my hair in a slick of olive oil. I sweated like a beast doing yoga in 40ºC. I contemplated the words of Deepak Chopra. I had cosmetic acupuncture on my face to erase wrinkles. Basically I have tried to follow the dictates of GOOP, Gwyneth Paltrow's lifestyle, new age-tastic website. And it has been exhausting.

There's a lot of Gwyneth Paltrow-hating out there. The actress was never really embraced by the unwashed hordes, being too preppy, too earnest. But the knives really came out last year when she launched GOOP. Named for her initials and childhood nickname, its goal is to "nourish the inner aspect" and each Thursday, subscribers can enjoy a newsletter falling under one of six headings: Make, Go, Get, Do, Be and See. One week she shares her favourite Barcelona addresses; in another, she gives us her fail-safe cookie recipes and extols the virtues of a strict detox.

A critic snarked that 'Learn from Me, Ungrateful Peasant' would have been a better moniker for the site. Do we really need advice from a rich Oscar-winning actress with a rock-star husband?

Two things are in her favour. Firstly, it's free and she's not hawking her own brand of pasta sauce or similar. Secondly, a lot of GOOP is the collected wisdom (or otherwise) of the experts and friends in her little black book, which includes every celebrity on the planet. You'd deem it name-dropping but what's a girl to do when her godfather is Steven Spielberg and her best friend is Madonna? But none of this overrides the fact that much of GOOP is a master class in the obvious (The Ritz Paris is a really nice place to stay? Really? No) or that it's patronising in the extreme.

What's apparent is that GP is a lady with a lot of time on her hands and lots of cash. Nothing is straightforward, not even the simple-sounding sugar and coffee body scrub – it requires Turbinado, a not readily available raw sugar made from sugar cane extract. GP is a keen cook and contrary to popular belief, doesn't only stick to a macrobiotic vegan diet. She does try to eat locally, seasonally and organically (as you do…), avoids processed foods or red meat and stays away from sugar and dairy. The 'Make' section is full of recipes with ingredients you have to google, like the sugar and gluten-free chocolate cupcakes with garbanzo and fava bean flour. Turkey ragout sounded delicious but sadly, the key ingredient – free range, organic, ground turkey meat – was difficult to source. "We only do that in the run-up to Christmas," two different organic butcher shops told me.

There are definite high points to the Paltrow way of existence. Bikram yoga: amazing. I join a class of about 40 other attendees at the studio in Harold's Cross for 90 minutes of 26 postures in 40º where the sweat runs off you like rivulets (note: white vests become see-through) and I have to lie down at intervals for fear of vomiting. But you've burnt about 600kcal and you do actually glow. Then there's cosmetic acupuncture at the Qi Rooms on Dublin's South William Street, a mini facelift involving needles inserted into the face and body to stimulate energy and blood flow and increase collagen production. "You eat a lot of cheese," Bridgette, the wonderful practitioner says with alarming perspicuity. "You need to stay away from dairy and from wheat and you need to avoid caffeine. That's why you have such black circles around your eyes." More than one session is recommended to see the best results but even so, there's a definite improvement to my skin and I float home.

Less effective are the Tracy Anderson workouts – she's the one credited with getting rid of GP's saddlebags and "post-pregnancy Shar-Pei-like stomach". There's not much impetus to do it in your kitchen, watching it on your laptop. I'm lazy like that. One workout is free on GOOP and the rest I download for $10 a pop from Anderson's own website, which amusingly leads to credit card services contacting me about suspicious activity on my account. Clearly arm-toning exercise webisodes do not fall under my normal spending habits.

So have I nourished the inner aspect? GOOP has me conflicted. Her intentions are honorable even if her sense of reality is skewed. Could GP swap places with any of us plebs doing a 9-5 and still continue on her sugar-free, vegan path, whilst fitting in acupuncture and Bikram sessions?

But for all her unrealistic notions, it's been a fascinating insight into the minds of a rich, alternative treatment-loving, health-conscious celebrity and as the woman who recently displayed the most appalling and unflattering flesh-coloured bra at Barcelona airport recently, you've got to concede that at one level, Gwynnie is just like us after all. But Lord, I am tired.

* Being Gwyneth Paltrow

Make: Sugar free/gluten free/vegan things. Do your food shop in a health store.

Go: To a cosmetic acupuncturist. Try it at pilates + qi rooms, 11 South William St, Dublin 2, tel: 087 909 2400

Get: Brian Atwood ankle books – a snip at €720

Do: Bikram Yoga. Unit 9, Greenmount Ind Est, Harold's Cross Dublin 12. www.bikramyoga.ie

Be: Positive. Negativity blocks happiness

See: A Sophia Coppola recommended film like vampire flick, Let the Right One In