It’s easy to develop a case of the latest psychiatrically acknowledged eating disorder, orthorexia nervosa – an obsession with avoiding foods perceived to be unhealthy. I got one for just £65. That’s the price of an introductory session at London’s Hale Clinic, an alternative therapy centre a couple of stuccoed blocks from Harley Street.

The Hale was opened by Prince Charles back in the 80s, and celebrities have been aromatherapied, ear-candled and detoxed there ever since. As you pass through its Grecian columns you cannot but ponder the fact that here Princess Diana’s colon was regularly irrigated. I arrive for something simpler: a consultation on my diet. I am a normal 50-something foodie whose diet philosophy has long been “Don’t eat crap” (with occasional cheesy Wotsits permitted). My complaints are pretty normal for my age cohort, too: a little joint pain, a desire to snooze after lunch, a failure to tolerate the quantities of alcohol I once enjoyed. Oh, and those close to me might mention a mild tendency towards flatulence. Like the bulk of the British public, I have a somewhat troubled relationship with my gut.

Today I have an appointment with the much-recommended Linda Crawford, a Hale Clinic veteran who is also principal of the College of BioEnergetic Medicine and director of the London Shyness Centre. She is cheerful and charming as well as multitalented: a psychotherapist, hypnotherapist, neurofeedback practitioner, kinesiologist, treater of chronic fatigue syndrome, dietary problems and – according to a recent promotional email – able to treat the potentially fatal Lyme’s disease by homeopathy.

Cooking up a storm: Princess Diana leaves the Hale Clinic in 1995. Photograph: Glenn Harvey/Rex Shutterstock

In an upper room that reeks of burning herbs, Linda straps a velcro band round my head. A lead runs from it to the back of her PC. She tells me to relax while she measures my body’s “stress response to certain hertz wave frequencies”. This is painless and a lot less hassle than a stool sample (I offered; it wasn’t needed). After 10 minutes or so my magnetic resonances have been fully read. Linda, with an I-told-you-so smile, prints out a sheet and hands it to me.

When large numbers of wealthy people declare the world’s most important food crop a poison, there is money to be made

It is amazing. I have won the hypochondriac lottery. I’m the owner of 29 different allergies, sensitive to substances from MSG to strawberries and including such regulars in my life as milk, chicken, wheat dust, red and green peppers, cheese, peanuts, honey, lentils, brewer’s yeast, lactose, various grasses, cat hair, tobacco and “summer and fall pollens”. The fact that I believe I have no hay fever or allergy is not of importance. I am aghast. I don’t know where to start. Cheese? I love cheese. “But your body doesn’t,” says Linda, wagging a finger.

Peering at her computer screen, a seer into a crystal ball, she finds other problems. “I see a lot of stress… I’m seeing insomnia, depression and constipation… Very stressed in the cranial nerve, the large and small intestine. Do you get constipated?” “No,” I say. “Hmmm… Is your memory poor?” “I’m a middle-aged man,” I say. “We tend to worry about our memories.” “That’s what I thought! I’m seeing stressed kidneys, which would affect your memory.”

This sparks my scepticism, not a common reaction at the Hale. But the diagnosis all seems a bit “You’ve met a tall dark stranger”. Ask any adult in later life if they are ever stressed or have sleeping problems, memory issues or depression and you are likely to get at least one positive. And whether it’s constipation or flatulence or irritable bowel syndrome, an astonishing 80% of adults are not happy with the workings of their bowels.

Diet guru Robert Atkins. Photograph: Rex Features

I question Linda a bit. What makes her so sure that my tendency to want a snooze in the afternoon is chronic fatigue virus? And why should gluten be responsible? “Gluten saps strength,” she tells me. “Put a piece of bread in your hand, put your arm out and push up against someone else’s hand. Then try it without. You’ll be amazed. It’s the same with dairy.”

I left the clinic with 14 baggies of tiny homeopathic pills for treating everything from memory loss to pituitary-gland malfunction. More arrived in the post in the next few days. I had expected to come away from the Hale instructed to eat a bit less bread and garlic for the sake of the atmosphere around me. But I went away promising to give up all gluten, dairy, eggs and chicken for four months at least. Including Christmas.

It was not a surprise (but it was a relief) to find, after many blind trials on friends, that the bread strength test doesn’t work. Nor does the dairy one. I binned the pills and felt really rather good.

Gluten free is growing faster than ‘organic’ did in the 2000s. There are labels on dog food and holy wafers

“Human credulity will never surprise me,” said a scientist friend when I told him this story. “Nor the self-indulgence of the healthy rich. But it is shocking how low the value of science has fallen.” With all science has done for us in the last century – doubled life expectancy and ended hunger in large parts of the world – you might have thought we’d have a little more respect for it and its rigours. But our ancient self-protective suspicion of food is so deeply entrenched that it must have an outlet. There is certainly much to be suspicious of in the modern, rich world’s foods – but it seems we’ve turned all that worry on to the wrong things.

And how we do worry. A couple of weeks ago, just down the road from the Hale Clinic in the marble halls of the Royal Society of Medicine, I watched a theatre full of dietary scientists and gastroenterologists discuss “Dietary controversies and the role of nutrition in western disease”. One of them, Maelàn Fontes of Lund University in Sweden, started his presentation with a series of Time magazine covers. They were all horror stories about food and heart disease, starting in 1961 with a portrait of Ancel Keys, the physiologist who first linked saturated fats with heart disease. There was the 1984 cover showing a frowny face in the shape of two fried eggs and a downturning rasher of bacon that got America worrying about cholesterol. All these scares changed the diets of millions. But, as Fontes pointed out, in each case the scientists were wrong, or at least were suffering severe wood/tree perception problems. In 2014 Time had a cover story that was almost an apology. “Eat Butter” it said, over a great curl of golden dairy fat. “Scientists labelled fat the enemy – why they were wrong,” announced the coverline.

Sister act: Melissa and Jasmine Hemsley. Photograph: Phil Fisk/The Observer

But these mishaps – and people my age will not easily forgive the years spent eating margarine instead of butter – have not diminished our readiness to sign up to new food fears. Take gluten. Until five years ago it was an obscure but important protein found in most cultivated grains. Today gluten is the new trans fat, an A-list evil food stuff. Gluten free or GF has risen, just as low cholesterol, low fat and high fibre before it, to be the top dietary fad of our times. In the US the GF market is worth $15bn a year – 30% of Americans believe they have problems with gluten.

GF is thus keeping health magazines busy and food manufacturers gleeful: the “free from” market is one of the few corners of the west’s cheap-food culture where big profits can still be made. GF is growing faster than “organic” did in the 2000s, and it is worth much more in terms of premiums that can be had. Manufacturers stick the label on dog food and communion wafers (causing a small furore at the Vatican). GF even goes on things that never had gluten in them in the first place, like chocolate and potato crisps.

Many allergies are genetic issues and their wider diagnosis the fault of poor science and crowd hysteria

It is a fabulous racket. When large numbers of wealthy people declare the world’s most important food crop – which, calorie for calorie, is what wheat is – a poison, there is money to be made. GF versions of pasta and bread and even chocolate brownie mix cost two or three times as much as the ordinary. No on-trend food business dares avoid GF – all the Hemsley sisters’s recipes spurn gluten. Ella Woodward, author of this year’s fastest-selling cookbook, Deliciously Ella, says she gave up gluten three years ago. According to Mintel, 60% of Britons have bought a GF product and the value of the market will rise to over £500m in the UK next year (organic is currently worth £1.6bn).

The problem is that only 1% of the population has the potential for coeliac disease, the condition where the body’s auto-immune system reacts to gluten, producing antibodies that can severely damage the gut. What the other GF shoppers may possibly have is gluten sensitivity. And for that there is no test. The tests you will be offered – of stool samples or saliva or blood, or, as with me and Linda, the electrical frequencies emanating from my forehead – are simply meaningless. “If nothing else, non-coeliac gluten sensitivity is a complex entity and will not give up its secrets easily,” says Dr Benjamin Lebwohl of Columbia University’s Celiac Disease Center.

The fact is that many people who feel bloated after eating a pile of pasta or a 10in pizza have simply eaten too much. Meanwhile GF replacements will contain other things your body may not like – after all, gluten is important if you like your bread springy. Extra fat is normal in the substitutes and so are sugar and salt. Chemical additives are used, too. Most reputable dietitians say people buying GF to lose weight are probably fat because of carbs and sugar, not gluten problems. In any case, it doesn’t work: three times as many GF dieters gain weight as lose it. Tim Spector, professor of genetic epidemiology at King’s College, London, has used his research into thousands of pairs of identical twins in a fascinating study of delusions about food, The Diet Myth. He shows pretty conclusively that many allergies are genetic issues and their wider diagnosis the fault of poor science and crowd hysteria. “Avoiding processed foods may be the only real benefit of GF diets,” he writes.

Time bombs: the 1961 cover of Time magazine with Ancel Keys, the physiologist who linked saturated fats with heart disease. Photograph: Time Life Pictures/Getty Images

Of course diets, all diets, whether daft or rational, may have a placebo effect – our food and our brains are closely related. Many people believe they feel better with less gluten, and that is good. When I told Linda Crawford I was writing an article sceptical about her methods, she offered me testimony from hundreds or thousands of people she has brought relief and comfort to. You can argue with that,but she makes an important point.

Powerful interests have invested much in gluten fear, just as they did in the animal fat scare. But ultimately the tide of fashion turns to follow the science. That may happen soon. The Australian research group that first fingered gluten as a problem beyond simple coeliac disease has now rewritten its findings, believing other things in natural food may be the culprits. Carbohydrates – remember the Atkins diet? – are coming back into focus as a cause of gut dysfunction; cutting down on them is again a sensible weight-loss strategy.

The scientists and doctors at the Royal College of Medicine evening were chiefly focused on the effects on the gut and its microbial occupants of the high-protein, low-carbohydrate “caveman” or paleo regime. At the Hale Clinic Linda Crawford thought this fashionable diet, the most Googled of all this year, was named after “somebody called Paleo”. But in fact it’s from paleolithic – early Stone Age – and rules out all but hunter-gatherer foods, including cultivated grains. At the RCM they were largely convinced by it – though the doctors didn’t shy away from the glass of wine and rather fancy canapés on offer at breaktime.

A hot tip for 2016’s top quasi-scientific dietary fad is Fodmap abstinence. The name can’t last: let’s call it the punishment diet, since it allows so little joy. It’s already big at the futurologising conferences where food manufacturers cosy up to nutrition scientists. The acronym stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. The science is complicated, but tests have shown people who believed they were gluten intolerant were instead relieved of tummy problems by cutting out these carbohydrates (while still, unknown to them, being fed gluten). The problem – and for manufacturers the money – lies in the fact this means lots of carbohydrates. Fructose has Fodmaps, and thus so do most sweet fruits, honey, dairy products, sweeter alcohols, garlic, onions, other vegetables and all the fizzy drinks full of high fructose corn syrup. Substitute sugars in many diet products, like xylitol in sugar-free gum, are also Fodmap substances.

Food scientists have no doubt who is to blame for the crazy whirligig of food scares and health advice U-turns. It is the media. The scientists have a point. Food science writers should be wary of the phrase “a new study shows”. Academic studies are just bricks in a wall – and you need to see the whole edifice. The WHO reviewed 800 academic papers before declaring, as it did in October, that processed meat, such as bacon, should be classed as a major carcinogen. But scientists and their sponsors – who are often the food industry – like loud headlines, too. A sacred cow being up-ended makes a noise, and in food science there’s always another long-held belief to be tackled. “Breakfast is not the most important meal of the day!” surfaced just before “Bacon as dangerous as cigarettes!” The latter reminded me of a diet plan that lots of us once followed – the Lucky Strike cigarette plan. A 1930s advert ran: “To keep a slender figure, reach for a Lucky instead of a sweet!”

Homeopathic help: some of the supplements Alex Renton was given after his consultation at the Hale Clinic, including treatments for memory loss and pituitary-gland malfunction

Bad science must take the blame, too, and in diet health there’s lots of that. It doesn’t take long to get a nutrition scientist to slag off the flawed design and improper deductions of their colleagues’ research. A presentation slide at the RCM made the participants smile. It was a graph showing the flags of western countries, plotted by chocolate consumption per head against Nobel prizes won per 10 million of population. Switzerland won by a mile. Yet no one would contend there was a correlation between eating Lindt and being great at science. Such deductive fallacies can be seen again and again in health research, usually because other factors have been ignored. Scientists are inherently biased to interpret data to the advantage of their ideas. Studies show that, too.

I don’t go on diets any more – cigarette based or otherwise – I just eat and drink less. After 10 years talking to scientists, reading papers and writing about food fads and food scares, I have arrived at a fairly comfortable place. I eat everything I like, but I try to follow the easy prescription of the food writer Michael Pollan: “Eat food. Not too much. Mostly plants.” Eat real food and don’t worry too much – it’s the fear-free diet.

As soon as one rateable celebrity goes public on a poo swap there will be a business started

For those of us bored by the endless contradictory flow of food fears and diet prescriptions there is some hope. The doctors at the RCM agreed that there is a revolution going on in nutrition science. For the first time, it is starting to consider humans as individuals. The rationale is that, after half a century of dictatorial orders, universal diet prescriptions are proven to have failed. If they worked, how do you explain how one human will live to be 100 on full-fat breakfasts and a bottle of wine a day while another will keel over at 50? That, on identical diets, some people get fat and others stay thin? At King’s, Tim Spector’s twins research explains those differences as being highly individualised and genetically based. The days of blanket diet prescriptions based on amounts of fats, protein and carbohydrates may be over.

This notion dovetails neatly with an idea which now has a weight of scientific enthusiasm behind it, including that of the paleolithic diet researchers. It is that the huge changes in human diet of the past 200 years have run way ahead of our ability to adapt genetically. That goes for our fellow travellers, too – the bacteria that live in our guts. Catering for them may be the answer to both uncomfortable digestive problems and the killer diseases of a poor diet, such as diabetes and bowel cancer. A science-based New York magazine article was headlined “The Future of Dieting is Personalized Algorithms Based on your Gut Bacteria” – suggesting there will come a time when each of us has a plan designed to boost or replenish our own particular family of microbes so they can break down the specific foods we have trouble processing.

You may be concerned that this will leave few opportunities for the food manufacturers or the homeopaths and nutritionists. But there is a new alternative therapy on the horizon. If an audit of your gut microbe population shows a deficit, then you may choose faecal microbiota transplant, or FMT. Here you transfer a portion of a healthy person’s faeces and all their microbes for a meet’n’mix party with the lonely ones in your colon. (This may be done from either end of the system.) As soon as one rateable celebrity goes public on a poo swap there will be a business opportunity. Practitioners will offer, as the nutrition adverts might put it, the ultimate solution to bloating and farting.

Diets: what’s in and out

Processed meat: fried bacon increases your chance of cancer by 35%. Photograph: Paul Taylor/Getty Images

UP

FODMAP diet It’s harsh: cut out bread, garlic, onions, many fruits and some vegetables, artificial sweeteners, honey and dairy products.



No sugar As simple as it sounds. You forego the substance that’s the prime culprit in the epidemic of obesity and diabetes in the west.

Eating clean – No processed food Manufacturers cannot be trusted or policed and will add whatever to food. Weight loss is usual. You win either way.

No bacon The salts used in curing meat have been declared a carcinogen. But chiefly when heated. Solution: air-dried ham for breakfast.

The paleo diet Not for creationists, this fashionable diet serves up what our ancestors ate 2.5m years ago. Definitely good for the waistline; less so for the pleasure centres.



The pre-biotic diet It’s not what you eat, it’s what your gut bacteria eat. So boost them with feasts of raw garlic, leek, banana, bran…

Satiation Choosing foods to trigger the hormones that tell your brain your stomach is full is an idea still on the nutrition scientists’ drawing boards. But drink two glasses of water before a meal and you’ll eat less.

DOWN

Ad nausea: smoking increases your chance of getting cancer by 2,500%.

Gluten free Just as Gwyneth Paltrow launched her line of GF readymeals (kale ravioli, anyone?) the scientists who thought gluten was the villain in digestive tract problems changed their minds. More GF dieters gain weight than lose it.

Bone broth A paleo dieter’s favourite – 12 hours simmering animal bones produces a collagen-heavy elixir that removes wrinkles, heals your gut and – according to basketball star Kobe Bryant – mends tendons. Science: doubtful.

Low fat Fifty years of advice was wrong. Turns out animal fats are not in themselves a cause of heart disease. Also they aren’t just better for you than margarine and other substitutes, but not eating them may harm children’s development and your own health.

The Lucky Strike diet Fags instead of food works, as models and ballet dancers know. But while eating lots of fried bacon increases your chance of cancer by 35%, taking up smoking pushes it by 2,500%.

Vegan People who eat nothing from animals are a little healthier and live a couple of years longer than average, but that is probably due to other lifestyle factors – vegans are usually pretty well behaved. New science on the gut microbiome and human genetics shows that cutting out meat and dairy is not right for all.

This article was modified on 25 November 2015 to correct the name of the Royal Society of Medicine and to identify Coeliac disease as an autoimmune disease, not an intolerance.

On 29 November 2015, the Observer published this letter:

Diet that cured my IBS

I take exception to Alex Renton’s treatment of the Fodmap diet in his article “What is healthy eating?” (Magazine, last week). To describe Fodmap as a “quasi-scientific dietary fad” represents a great disservice to those of us with IBS. While many diets have little or no scientific basis, Fodmap is not one of them. The low Fodmap diet was developed at Melbourne’s Monash University by a professor of gastroenterology and a dietician. Here in the UK, Guy’s and St Thomas’ NHS foundation trust offers training on the Fodmap diet to registered dieticians. As a long-time sufferer of IBS, I was pleased to be referred by my GP to a dietician with this specialist training. Following the Fodmap diet was the best decision I have ever made as I can now lead a normal life.

Margaret Young

Edinburgh