Lunch at Katie Caldesi’s house is a glorious affair —richly flavoured, bite-size samples from her latest recipes are set out on the table, an enticing smorgasbord of savoury, piquant and subtly sweet. But all is not quite as it seems.

The squares of beef cottage pie, studded with diced swede, turnip and carrot, are topped not with traditional mashed potato, but with a crust of nutty celeriac.

The bread rolls, still warm from the oven, contain no flour. Instead, they are made from ground almonds and eggs. And Katie’s rosemary and apple mini muffins slathered in cream cheese frosting are neither cloying nor sugary. They, too, are flour-free and their delicate, herby sweetness is derived only from fruit.

Katie Caldesi with her husband, top TV chef, Giancarlo. Katie has revealed the delicious low-carb recipes that reversed her husband's type two diabetes

Food writer Katie — who, with her husband Giancarlo, runs two restaurants and a London-based cookery school, La Cucina Caldesi — is Britain’s most accomplished exponent of low-carbohydrate cooking.

Today, as we bring you the first batch in a series of tempting low-carb autumn recipes she’s devised exclusively for the Mail (see Weekend magazine), Katie explains the extraordinary health benefits of an eating regimen that involves neither self-denial nor calorie-counting, but could help you lose weight and more importantly, reverse type 2 diabetes.

As part of this month’s Good Health For Life series helping to put patients back in control of their health, Katie has teamed up once again with NHS GP and diabetes expert Dr David Unwin in a brilliant series of pullout guides for the Mail on how to use a low-carb approach to tackle a problem that affects nearly four million Britons. (A study this week even revealed one in eight new cases of type 2 diabetes in the UK is now in the 18-to-40 age group because of the obesity epidemic.)

One patient was Katie’s husband Giancarlo. Tall, serene and softly spoken, her outward calm belies a restless creative energy that drives her to rise at dawn to cook or write.

Today, Katie glides around the kitchen of the family home in Buckinghamshire, quietly assembling food on plates, while the younger of her two sons, 17-year-old Flavio — rangy and lean — cooks a brunch of spicy sausage and homemade tomato sauce, piling it artistically on to a trencher.

She has been devising low-carb recipes since 2011, when Giancarlo was diagnosed with type 2 diabetes. Yet, despite following a private doctor’s advice (endorsed by the NHS) to cut back on sugar and reduce his portion sizes, he actually worsened.

By coincidence, Katie, 56, stumbled on the real link between her husband’s diet and the disease. Suffering from bloating herself, she decided to eliminate gluten (a protein found in wheat) from the family’s diet. And, when she cut out starchy foods — not just wheat-based products such as flour and pasta, but rice, potatoes and other carbs — as well as sugar-laden puddings, the effect on Giancarlo, 66, was miraculous.

Although his favourite pasta and profiteroles were gone, he didn’t miss out, thanks to the regimen Katie devised.

Her recipes are abundant and flavoursome: full-fat yoghurt, cream, cheese and butter in place of processed low-fat spreads and skimmed milk. Nor is there a prohibition on rich, meaty ragu sauces or aromatic, warming stews.

Under this new eating plan, not only did Giancarlo’s waistline shrink — he lost 3 st — and his old energy return, but his type 2 diabetes went into remission. The low-carb diet saved his life.

Type 2 diabetes is a condition that makes it difficult for the body to process sugar, so its levels become too high. Associated with obesity and lethargy, diabetes can, if uncontrolled, also cause sight loss and diabetic neuropathy (nerve damage), which, in extreme cases, can lead to amputations.

Almost four million people in the UK have diabetes, of whom around 90 per cent have type 2. Two out of three will go on to die from its complications if it is not reversed.

Katie recalls its effects on her husband. ‘When I met Giancarlo 21 years ago, he was so lively and energetic his customers called him Tigger,’ she says.

‘But we both loved food and were overweight. We had our sons, Giorgio, now 19, [who is living in Japan and learning the language before he begins a business studies degree] and Flavio [still at school].

‘Then, in 2005, we opened a cookery summer school in Tuscany. We were getting married there six weeks later in Montepulciano, where Giancarlo grew up.

‘Life was frantically busy, and it was all being televised [for BBC series Return To Tuscany], so I really wanted to lose weight for the wedding. I was so terrified of not being able to fit into the dress that I burst into tears at the fitting.’

She continues: ‘I was a busy mum running two cookery schools and I exercised a lot. I got down to my lowest-ever weight, 10 st (I’m 5 ft 9 in), for our wedding.

Giancarlo and Katie before his type two diabetes diagnosis. Speaking about her husband, Katie said: 'He had frequent, excruciating attacks of gout, arthritis in his hands, and everything was an effort'

‘But Giancarlo didn’t lose weight. He kept piling it on. And he’d say: “I’m getting old. Everything aches.” He started taking afternoon naps. He also said his feet were numb and stopped playing football with the boys — though he loved it — as his feet didn’t “work properly”.

‘He had frequent, excruciating attacks of gout, arthritis in his hands, and everything was an effort. He’d come home from work like a bear that hadn’t been fed, saying: “I need to eat! I need to eat!”

‘He’d cook himself pasta and gorge on it straight out of the saucepan, or devour the entire contents of the fruit bowl — one-and-a-half melons, bananas.’ He was also incredibly thirsty.

‘Now we know he had the classic symptoms of type 2 diabetes, but at the time, we hadn’t a clue what was wrong,’ says Katie. ‘Then he started to complain of blurred vision. And, one day in 2011, his sight went as he drove home.

‘He phoned me and said: “Something odd has happened. I can’t see properly.” He was really shaken. We wondered if it was a stroke. He waited in a lay-by until his sight came back and he drove home.’ A private GP ran tests — which revealed Giancarlo was diabetic.

‘The doctor gave him a choice. He said: “I can give you tablets, or you can avoid sugar to try to control it.” Giancarlo said he’d cut back on sugar, which just meant he stopped taking it in his coffee,’ says Katie.

‘No one explained the crucial fact that starch — in bread, pasta, rice and potatoes — releases sugar molecules into the body, causing a surge in blood sugar just as quickly as cakes, sweets and biscuits.’

So Giancarlo, who at more than 16 st (he’s 5ft 9in) was clinically obese, continued to eat bowls of pasta.

In 2013, a second set of tests confirmed his blood sugar levels had risen. Then, a year or so later, Katie chanced upon the solution.

Suffering from irritable bowel syndrome, feeling bloated and also needing to lose weight), on the advice of nutritionist Jenny Phillips, she began to cook gluten-free food.

This meant banishing Giancarlo’s favourites of pasta, bread, pizza and profiteroles. To begin with, he was bereft. ‘But, within three days, he started to lose weight,’ says Katie. ‘He was also brighter, less sleepy and his energy came back.’

She researched low-carb diets and discovered a GP, Dr David Unwin, who had achieved successes in reversing type 2 diabetes among patients in his Southport practice. She asked if he would collaborate on a cookery book and, with Giancarlo, they produced The Diabetes Weight-Loss Cookbook, serialised in the Mail this year.

Five years after his diagnosis, tests showed Giancarlo’s diabetes was in remission. ‘By 2017, he had lost 3 st and no longer had numbness in his feet or blurred vision,’ says Katie.

Crucially, Giancarlo also relishes his new way of eating, and low-carb options — among them courgetti spaghetti, pan-fried king prawns and vegetable ribbons, salami with air-dried salted beef and grilled veg — now feature in the menus at the family’s restaurants in Bray, Berkshire, and Marylebone, London.

Katie, too, has shed a stone in weight (she is now a healthy 10 ½ st) since going low-carb. She was, she says, acutely aware of her family’s propensity for weight gain — her adored mum Elizabeth became obese in old age and was suffering from health problems — among them vascular dementia and high blood pressure — when she died at the age of 86.

Elizabeth was also an excellent cook, and it was she who imbued Katie with a passion for food.

Her father Jim ran his own bookshop, but the business struggled in the Eighties. ‘My parents lost everything,’ says Katie. ‘I was at art school with an overdraft and they sent me £10: such a generous gesture when they had so little.’

Meanwhile, her mother continued to ail: she had a knee replacement and, at size 24 and weighing 22 st, was urged by doctors to lose weight.

But the dietary advice she was given, Katie realises, was ill-informed. ‘Mum was advised not to have so much butter on her bread, so she changed to low-fat spreads.’ These are now known often to contain high levels of fats associated with heart disease.

‘Mum would have been better off cutting down on bread and putting butter on her vegetables instead.’

Katie had wanted to become a chef, but back then, there were few opportunities, so she pursued her passion for painting. It was art that drew her to Giancarlo when she was commissioned to paint a mural for his London restaurant.

‘He says as soon as he shook my hand, he decided that he was going to marry me and we’d have two children,’ she smiles.

They set up home in two cramped rooms above the restaurant and Katie began working in its kitchen, acquiring the skills that have equipped her to run their cookery schools and restaurants.

Eleven years ago, they moved to their current home, where Katie’s parents lived with them until they died. In her parents’ former sitting room, she now writes her books —13 to date.

A low-carb diet would have helped her mum, Katie reflects. ‘I wish Mum had been well for longer,’ she says. ‘She would have loved testing recipes with me. When I lost her to dementia, it was such a blow.’

She adds: ‘It’s time we all understood what food does to our bodies. Few of us realise that a serving of basmati rice has the equivalent effect on blood sugar levels as ten teaspoons of sugar.

‘And few of us realise that a low- carb diet could save our life.’