What do glossy Gwyneth Paltrow, the enticing Hemsley sisters and fresh-faced Ella Woodward have in common? The answer's simple: they all have a vehement antipathy to wheat. These cookbook queens would no sooner let a baguette pass their lips than admit they didn't really like the taste of that trendy grain du jour, quinoa.
Why? Well, firstly, when you ditch wheat and, more specifically, other food products containing gluten - the protein found in wheat - you generally lose weight. And lots of it.
Indeed, many of the most popular weight-loss diets, such as Paleo, Atkins and Dukan, are founded on the principle of cutting right back on gluten. Just look at the tiny figure of Victoria Beckham to see what sustained avoidance of the stuff can do to your waistline.
But there's more to the gluten-free trend than weight loss.
This breed of healthy-living advocates say not eating gluten makes them feel healthier, lighter, less sluggish. Tennis star Novak Djokovic even claims giving up gluten has sharpened up his game.
So should you give up gluten? Could ditching bread, pasta and cakes help you feel as glowing as Gwynnie or as determined as Djokovic?
In this three-part series, we'll be asking whether the gluten-free craze is just faddishness, fuelled by clever marketing, as well as speaking to those who say that going without it has been transformational.
And we'll guide you through the gluten maze with our quiz, which will reveal if your life could be changed for the better if you gave up gluten.
So why, if you're not actually allergic to gluten, would you give it up?
There's a growing belief large numbers of us struggle to metabolise gluten effectively. Some experts believe our delicate digestive systems may not be robust enough to tolerate modern, industrially produced wheat - certainly not in the quantities in which it's typically consumed.
And so, slowly, consumers have begun turning away from gluten, leading to a boom in the 'free-from' supermarket sector.
A recent report found that 60 per cent of people purchase or consume at least some gluten-free products and one household in ten - that's some 2.7 million - contains someone who believes gluten is bad for them.
Yet if you ask your GP what they think about giving up bread, you are likely to get short shrift.
Most doctors believe that gluten causes problems only if you have coeliac disease, where the immune system reacts to gluten, damaging the gut and preventing vital nutrients from being absorbed. Coeliacs have to follow a gluten-free diet for life to prevent long-term problems.
But coeliac disease affects only one in 100 people in the UK - an estimated 125,000. Although this figure is on the rise (up from one in 8,000 in the Fifties), it represents a small sector of the population compared with the vast numbers trying to avoid gluten right now.
Medical experts are divided on whether this surge in going gluten-free is a sensible response by people who've found their own cure for dietary discomfort - or just plain crazy.
Some, like Dr Peter Green, a U.S. coeliac specialist and author of Gluten Exposed, believe the world has gone mad.
He is emphatic: the popularity of going without gluten has been fed by endorsements from athletes and actors, which, he says, 'speaks to our infatuation with celebrities and fad diets'. He also points to the placebo effect - that people giving up gluten are seduced by their desire to believe in something so passionately that it works.
Dr Green warns of a gluten-free con. 'In the past few years gluten has become the ultimate villain,' he says, 'It is implicated in everything from heart disease, neuralgia, sore muscles, exhaustion, brain fog, headaches, autism, diabetes, arthritis, curious rashes, schizophrenia, dementia, weight loss, fibromyalgia and irritable bowel syndrome to plain "it makes me feel sick-itis".'
Yet, he says, 'most of these claims do not stand up'. Too many people, he says, are bundling coeliac disease in with dietary fads.
But other experts, such as Professor David Sanders, author of Gluten Attack, argue that it really can trigger gut problems in large numbers of people - sometimes without them realising.
His proof? The stream of patients he has seen over many years in his clinic "who do not have coeliac disease, but say they have symptoms such as bloating, pain, diarrhoea, constipation and feeling sluggish when they eat gluten".
He has come to accept the possibility of an in-between condition he terms "coeliac lite" - someone for whom coeliac disease has been ruled out, but whose symptoms improve on a gluten-free diet.
Some specialists refer to it as gluten sensitivity, non-coeliac gluten sensitivity, or wheat or gluten intolerance.
"However," he says, "This is something we are only beginning to understand.
"It was only when I stepped away from what I was taught didactically during medical training and instead asked open questions about what I was seeing and hearing from my patients that I came around to this way of thinking."
Professor Sanders's research has shown that many of these "coeliac-lite" patients are female, in their 30s to 40s, with a high prevalence of irritable bowel type symptoms. In other words, the exact market that clean-eating gurus such as Gwyneth Paltrow are trying to seduce.
Professor Sanders admits that the idea of "gluten sensitivity, or coeliac lite, is a controversial one - for now. But the fact is our understanding of what happens in the gut is evolving rapidly."
This could explain why so many insist going gluten-free has helped their health as well as weight.
There's one other possibility explaining the gluten-free boom, which is more concerning: that thousands of people with coeliac disease don't know they've got it.
Coeliac disease isn't always easy to spot. Symptoms include bloating, diarrhoea, weight loss and tiredness, which are similar to other conditions such as irritable bowel syndrome. Indeed, they can even be common side-effects of a busy working woman's lifestyle.
So experts warn that there could be as many as half a million people in the UK with undiagnosed coeliac disease, which is either symptom-free or presents itself with seemingly unrelated symptoms such as headaches or a skin rash.
Dr Green is the first to admit that the food industry's canny marketing of "free-from" products has stolen a march on the medical community. Gastroenterologists, he says, are "now playing scientific catch-up".
"With the advent of the internet, everyone has become a medical researcher," he says. "This has left room for the public to run away with ideas and point fingers at gluten as the cause for anything and everything. Gluten has become a media-borne epidemic."
With so much confusion among medical practitioners, it's perhaps hardly surprising that so many people take their diet into their own hands and choose to go gluten-free.
What is Coeliac disease?
Coeliac disease is a lifelong condition where the immune system attacks its own tissue in response to gluten, a protein found in wheat, barley and rye, and present in nearly all bread, cakes and pasta.
It is normally associated with gut symptoms as the body's immune response damages the digestive system.
It causes diarrhoea, bloating and abdominal pain, as well as fatigue and anaemia because not enough nutrients from food are absorbed sufficiently.
* Gluten Exposed: The Science Behind The Hype, by Dr Peter Green and Rory Jones (Fourth Estate, £14.99).