Dylan Cooper is on a dietary regime that would put even the most health conscious among us to shame. He cleanses his system with chia seeds for breakfast and eats spinach cooked in coconut oil for lunch.

Quinoa stir-fry is a favourite for dinner and the nearest he gets to fast food is home-made chicken nuggets coated in spelt batter.

But his is not a cliched January detox, one to be as quickly discarded as it was once enthusiastically embraced. Nor is Dylan the driving force behind it. Because blond-haired Dylan is only two years old. Determined that her son would avoid what she regards as 'toxic' and 'harmful' foods, his mother Lizzy has never allowed her son to eat food with added sugar or any refined carbohydrates such as white rice and bread.

As one of a growing number of so-called "clean-eating" babies and toddlers, Dylan has yet to slurp a strand of white spaghetti or enjoy a piece of gooey chocolate cake.


And if Lizzy has her way, he never will. "People think I am being cruel in denying him certain foods and that Dylan is missing out," she says.

"But I want him to have the best start in life before he goes to school when I will be less able to shield him."

The popularity of "clean eating" - in which processed food is banned, often along with entire food groups - has soared in the past couple of years, with celebrities from Gwyneth Paltrow to Davina McCall espousing the virtues of a diet devoid of wheat, carbohydrates and sugar.

Food blogger Ella Woodward goes even further and eschews meat, dairy, eggs, gluten and refined sugars - an unappetising prospect, you might think, and yet her recipe book, Deliciously Ella, became the fastest-selling ever when it was published last year.

And it seems such puritanical regimes are being passed from parents to children at an astonishingly young age. Last month, Australian mother Shan Cooper sparked international controversy when she revealed her 13-month-old daughter Grace was on the Paleo diet, which involves eating only meat, fish, nuts and vegetables and avoiding refined carbohydrates or wholegrains.

Whether babies should be weaned in such a draconian way divides opinion. Is this an effective method of targeting rising childhood obesity rates? Or an obsessional approach to food that will ultimately do a youngster more harm than good? Anna Daniels, of the British Dietetic Association, fears it is the latter.

"Parents who are fanatical about avoiding certain foods risk transferring this fear on to their child which could lead to eating disorders in later life," she says.

"Even if children don't realise they are on a specific "diet", they will subconsciously be influenced by the food choices made for them, which could lead to social exclusion when they make friends with children who are allowed these foods and an unhealthy preoccupation with body image."

Their health can suffer too, she says. "If children go without dairy their bone development might suffer, and going without adequate carbohydrates is hugely damaging for growth and development."

Lizzy, 22, a housewife married to Dale, 26, an IT consultant, became preoccupied with her son's diet in spring 2014, when he was just two months old and she watched a documentary film called Food Matters.

It claimed chemicals used to grow food, combined with poor soil quality, are creating mineral-deficient crops that are making us ill, while suggesting organic and unprocessed food can combat ailments from cancer to heart disease and depression.

It prompted Lizzy to overhaul her family's diet. She swapped potatoes for more nutrient-dense sweet potatoes and started cooking with coconut oil on account of its purported antioxidant qualities.

"I didn't want my son to eat anything potentially harmful. Not only do refined carbohydrates contain toxins and chemicals, but they are addictive with no nutritional value," she says.

Lizzy was studying health and social care when she found out she was pregnant and decided to be a stay-at-home mother so she could monitor her son's diet.

She breast-fed Dylan (she believes formula milk to be toxic) for 18 months, introducing solids when he was five months old in the form of mashed swede and sweet potatoes. Over the following months she added organic chicken and fish.

By his first birthday - which he celebrated with a bite of home-made spelt flour cake, made with apple sauce instead of sugar - Dylan was eating flax and chia seeds on his porridge, topped with natural peanut butter from a health food shop. Sweets and chocolate are banned.

Lizzy swears the regime is reaping benefits. Dylan has "lovely" skin, she says, and has only had two colds since he was born. Her devotion to her son is admirable, but is it sensible? Dietician Anna Daniels isn't convinced.

"Wholegrain carbohydrates are healthier as they contain more nutrients, but white pasta and bread are absolutely fine in moderation," she says. "And there is no evidence we should use coconut oil, which is high in saturated fat and very  expensive."

As for a blanket ban on sweets and chocolates, she warns: "If children aren't taught how to eat foods like these on occasion they may over-eat other foods to compensate."

Dylan is still too young to understand what he is missing, but the impact of his clean-eating on his parents' marriage has been considerable.

"At first Dale was upset because I was obsessive and it caused arguments. I was so strict that we couldn't go anywhere with Dylan without taking our own food. I often turned down dinner invitations with friends as it was too complicated explaining what we could and couldn't eat,' says Lizzy, who spends 90 minutes a day cooking for her son.

"I hated not being able to control everything Dylan ate. Dale, meanwhile, started hiding sweets for himself in his drawers. Things came to a head six months ago when he gave Dylan a mouthful of a cheese and onion pasty while they were out. I was angry. I told Dale he shouldn't be eating processed food like that and Dale said he couldn't do this diet any more. In the end, we agreed it was best for Dylan, but that Dale would eat normally when he wasn't with us. I promised I would try to be more lenient."

It's proving a struggle, however, and she admits her friends also find her behaviour extreme.

Meanwhile, Lizzy is dreading the day Dylan starts nursery school next year. "The idea of losing control of his eating feels horrible, but I don't want Dylan to be left out and know I won't always be able to be this strict."

Maternity nurse Rachel Waddilove, author of The Toddler Book: How To Enjoy Your Growing Child, believes mums like Lizzy need to relax a little. "Our attitude towards our children's diets has got out of hand and mothers are worrying far too much about what their children eat," she says.

"To cut out sugar is bonkers. There are so many so-called experts pushing healthy eating to extremes on parents who just want to do the best by their children."

But plenty of mothers are susceptible to the clean-eating message. Take Emiliana Silvestri, 36, who is bringing up her 11-month-old daughter Coco-Rose on a gluten-free and predominantly wheat-free diet. She doesn't have coeliac disease - the autoimmune disease that affects 1 per cent of the population, in which the small intestine is hyper- sensitive to gluten, a protein in wheat.

She has eliminated processed foods on the grounds they may set up unhealthy eating habits for the future.

"Coco doesn't have any allergies, but fish, chicken, fruit and vegetables are pretty much all she eats because they are the healthiest foods a baby can have," says Emiliana, a self-confessed "food Nazi".

"Childhood obesity is a concern - being overweight is just awful and I don't want that for my daughter, or for her to develop stomach upsets that eating gluten can cause.'"

After consulting various "health expert" friends, Emiliana, a relationship coach, cut out wheat and gluten from her own diet four years ago and lost nearly 20 kilograms, shrinking from a size 14 to a size ten.

The following year she met Coco's father - David, 35, a special needs teacher - who she also persuaded to go gluten-free.

Gluten-free food for non-coeliac sufferers has become fashionable in recent years, espoused by celebrities and claimed to cure everything from weight gain to dementia.
Yet Anna Daniels says: "There is absolutely no advantage to cutting gluten out of your child's diet unless they are coeliac or sensitive to gluten, and in doing so you run the risk of excluding important carbohydrates.

"Children who eat too few carbohydrates might experience muscle wastage, unhealthy weight loss and lack the fibre they need for good digestion.

"Plus, gluten-free alternatives of foods such as certain packaged breads might be full of undesirable additives. They may be higher in sugar to make them more palatable and contain thickeners, modified starches, stabilisers, bulking and  raising agents to give the desired consistency."

"A child's diet should be 50 per cent carbohydrates and those contained in fruit and vegetables are not enough, given the energy babies and toddlers expend and their rapid development."

A breast-fed baby, Coco-Rose was weaned on organic fruit and vegetables at five months, with chicken and fish - organic from the local fishmonger and butcher - introduced when she was nine months.

She has sweet potato and white fish for lunch and chicken stew heaped with vegetables for dinner, with her mum adding a spoonful of the fashionable grain quinoa in every meal (including her breakfast yogurt) for extra protein. And that is pretty much it.

Emiliana has already encountered opposition to her daughter's diet. "When I told my neighbour she couldn't give Coco chocolate I upset her, and some friends have said that going gluten-free is a load of rubbish. But I'm not going to buy food I know is harmful to our family."

Such criticism will inevitably increase as Coco-Rose grows up. "I might send her to an alternative school where she can bring in a packed lunch and I will make her a gluten-free cake on her birthday," says Emiliana.

"Her skin is beautiful, she's rarely ill and, at 10.4 kilograms, she is a healthy size for her weight. She is by far the healthiest of all her baby friends and she loves the meals I give her - she is obsessed with food."

Despite the criticisms of imposing such extreme diets on young children, there are experts who believe they have merits.

"Babies have a good chance of preferring real food for life if they avoid processed food," says nutritionist Zoe Harcombe, author of The Obesity Epidemic: What Caused It? How Can We Stop It?

"It is a big effort for parents, who are probably getting criticism from all angles. And yet they are doing the right thing. I admire them."

Even more controversially, some mothers are putting their children on diets intended for adults. Thirty year old Nikki Whelan has fed her 18-month-old daughter Lucie on an adapted version of the Slimming World diet since she was weaned at six months old to ensure she doesn't get fat.

Followers will eat unlimited quantities of lower-calorie, higher-nutrient "free foods", which include fruit, vegetables, pasta, potatoes, fish and lean meat, with rationed amounts of "healthy extras" that include bread, cereals, cheese and milk.

"She has never eaten chocolate. I don't want her fuelled by junk or the type of sugar-filled snacks targeted at children," says Nikki.

"It makes me sad that people are so uneducated they don't realise how bad for a child these baby foods are.

"There is so much sugar in a rusk that you're basically feeding your baby a biscuit."

Nikki and her husband Pete, 33, a theatre manager, are Slimming World devotees after using the diet to lose weight five years ago.

"I lost 25 kilograms, going from a size 18 to a size ten and 55 kilograms. Pete lost nearly 30 kilograms, going from 108 kilograms to 77.4 kilograms.

"It taught us to ensure we have enough fruit and vegetables with every meal to limit things such as bread, dairy and treats," says Nikki.

"We let Lucie eat as much dairy as she likes, but limit her bread intake to one slice of wholemeal a day as there is a lot of sugar in it. We don't think of it as a "diet". It's just healthy eating."

Anna Daniels isn't so sure: "Putting a child on a diet at that age can be damaging and lead to unhealthy body image," she says.

For the time being, at any rate, Lucie seems happy with the food she is given.

"The first food she ate was broccoli and now she might have an omelette for breakfast, a cheese sandwich with wholemeal bread for lunch and quorn bolognese with courgettes, peppers and kale for dinner," says Nikki.

"Lucie can be fussy with vegetables, but the more we offer, the more she gets used to them."

Nikki - who says she'll make her daughter a packed lunch when she starts school so she can continue to clean-eat - admits her past struggles with her own weight fuel her daughter's strict diet.

"To have anyone say my little girl is fat would break my heart. A baby is a blank canvas where nutrition is concerned, and I won't let Lucie become a national obesity statistic."