Six months ago, I took a leap into the unknown. In a desperate bid to reclaim my health and shed the weight I had carried for far too long, I did something most would consider mad: I stopped eating. Not for a day, or a week — but for 23 days.

No food. Just water, black coffee and sheer determination.

The pounds began to pile on during the pandemic, with first Covid and then a knee injury meaning I couldn’t exercise like I once did.

At 58, I was tipping the scales at 17st 7lb — medically obese for someone 5ft9 tall. I was also pre-diabetic, struggling with high blood pressure and heading for a knee replacement.

I couldn’t see my toes, couldn’t breathe in an XL shirt, and couldn’t ignore the truth any longer.

My waist size was heading north of 40 inches — not a good look for a TV presenter.

No fad diet was going to fix this. I needed a reset. A radical one.

There are, of course, more sensible and less dramatic interventions, but I was attracted by the near-immediate fix — to transform my health and appearance in less than a month.

I embarked on this extreme fast under the supervision of Dr Ash Kapoor, a pioneer in regenerative medicine. We met nine years ago when he was my GP, but now he runs his own private health clinics in London and has become a leading authority on how fasting can improve our wellbeing and help us live longer.

It does so by replicating what happens in times of famine, when our bodies are forced to dine on reserves of fat, protein and sugar stored within our cells and around our organs. The internal larders we never visit in modern times because we are in a perpetual state of abundance, eating three times a day despite most of us being fairly sedentary.

By fasting, we empty these larders — a process known as autophagy, meaning ‘self-eating’. This effectively restores the body to factory settings, recycling the cellular material into brand new DNA and using it for energy.

Donal Macintyre before starting his diet, at 17st 7lb

Six months on, the TV presenter has kept the weight off – and lost even more

Dr Kapoor, author of the book Autophagy: Release Our Internal Larders, never had a fasting patient go beyond two weeks. I lasted for just over three.

Normally, this kind of deprivation is reserved for hermits, but I was surrounded by food, restaurants and supermarkets. Every temptation in plain sight.

With regular diagnostics to make sure I wasn’t endangering my health, I also had weekly IV drip infusions of salt, minerals and vitamins A and B — which the body doesn’t produce naturally.

What followed was nothing short of miraculous.

As I recorded my results in February, I lost 43lbs – around three-and-a-half stone. My waist dropped from 40 to 36 inches. My blood pressure normalised and my blood sugar levels fell out of the danger zone, meaning I am no longer pre-diabetic. And best of all? I didn’t need knee surgery.

It was extreme, but it worked. No Ozempic or Mounjaro. No pharmaceutical crutch. And without any of the saggy skin usually associated with rapid weight loss.

Of course, many people were sceptical, not least the Mail readers whose online comments suggested that the before and after photos were a trick of good lighting and even belly-sucking.

Others doubted whether the ‘timber’ would stay off, predicting that I’d crack and bounce back to my original weight. Well, I didn’t.

Six months on, I’ve lost another 7lbs — bringing the total to 50lbs gone. Forever, I hope.

That, of course, will depend on me keeping to the new eating habits I’ve developed since completing the fast. In the days immediately afterwards, it would have been dangerous to reintroduce solids to my body too quickly, so it was three weeks of soup before I could enjoy the treat I’d been dreaming about — a succulent rib-eye steak.

Donal says of his fast: ‘It was extreme, but it worked’

Queuing at my local butcher’s on a Saturday morning, excited about choosing the juiciest one, I was eager to cook it, and when I did, I cherished every mouthful.

That first steak was eaten without any accompaniments but, I have since had others with onion rings and big fat chips, I’m very aware that food is my addiction.

I knew that I had to break its hold and I seem to have succeeded. For now, my regime is a dramatic improvement on my previous hourly snacking on crisps, bars and biscuits. I eat one meal a day — mostly. I stick to big salads, lean proteins, and low carbs. I still have cravings. I hanker after chocolate digestives and cheat with a few over coffee.

A mojito and a few beers isn’t totally out of the question, and I still fall off the wagon sometimes at weddings or parties. I’m not perfect. But I’m consistent. And that, it turns out, is enough.

I’m lighter, stronger, and more energetic than I’ve been in years.

When I get up off the sofa, or out of the car, it’s without the grunting that started to accompany every bit of effort.

Now I’m training four times a week: running, canoeing, lifting weights. Nothing too strenuous but it’s burning enough calories to build on the progress I’ve already made. Beyond motivating me, the success of my fast has also inspired something bigger.

Research suggests autophagy can help reduce inflammation associated with a range of chronic conditions including Parkinson’s, multiple sclerosis (MS) and dementia.

So, together with Dr Kapoor, wellbeing specialist Tim Lodge, and the Samson Centre for MS in Guildford, Surrey, we’re launching a £50,000 pilot study to help the wider community.

The scheme, launched this week, will see ten people with MS receive free longevity treatments – including medical check-ups, blood testing, scans, oxygen therapy, free supplements, nutritional and wellbeing coaching – worth £5,000 per person. Plus, of course, a bout of fasting for each individual participant – but not 23 days!

Dr Kapoor’s vision is bold: ‘It’s about democratising longevity. Everyone deserves the chance to live well and long.’

In ten years, every community could have access to a medically supported fasting and ‘living healthy for longer’ programme.

That would be a fantastic legacy beyond my own vanity and fitting into size 34-inch jeans.

I still haven’t treated myself to a new wardrobe.

Maybe because, until now, I was nervous about the weight coming back on. But it’s so nice to see how much looser my clothes feel.

I’m already enjoying looking more like a TV presenter should, with no weight-disguising camouflage required when I go on camera.

Next month I’m planning to hit the clothes shops but my weight-loss journey is not over, and my ultimate ambition remains.

When I began, my goal was to lose 60lbs by 60.

I’ve got 10lbs to go, and six months left. Come January next year we’ll see if I can hit that mark and complete my mission – from medically obese to healthy ‘dad bod’ – in one year.

No gimmicks or gurus. Just discipline, science, and support.

If I can do it, maybe others can too.

Let’s find out.