Jack Mosley: ‘People who never knew my dad felt like they had lost a friend'

Telegraph

29-05-2025

The lucky among us cite our parents as inspirational figures in our lives, but for Dr Jack Mosley, 32, it's a sentiment that is particularly true. His father, the late Dr Michael Mosley, was the nation's trusted authority on how we should be improving our health, sharing his evidence-backed advice through television documentaries, books and his Just One Thing podcast until he died of suspected heatstroke last June while on holiday in Greece.
Weight loss was a theme that ran through his projects – from playing the guinea pig for intermittent fasting and ingesting tapeworms in a bid to lose fat, to writing books that popularised the 5:2 and Fast 800 diets, which helped the masses shift the scales.
Now, seven years after becoming a doctor and a year on from his father's death, his son Jack, the only one of his four children to become a doctor, is continuing to follow in his father's footsteps with his book Food Noise. It navigates the new world of GLP-1 weight-loss drugs, better known as Wegovy, Ozempic (technically a Type 2 diabetes drug) and Mounjaro. He explores how they work, the risks and benefits, and how to use them safely.
'My dad was clearly a massive inspiration to me,' Jack says. 'He would have written a book on weight loss medications had he not passed away.' The book is dedicated to Michael, whom Jack describes as a 'guiding light'.
'He could see that the GLP-1s could be a massive breakthrough in obesity,' he says. 'We talked about them around the dinner table. He was very excited about them but could see they were a tool in the toolbox to combat obesity, rather than replacing the toolbox altogether.'
'When he passed away, we ourselves as a family didn't really know the scale of how many people he made such a difference to,' Jack says. 'People who never knew him felt like they had lost a friend. I think that was such a testament to how much help he gave to so many people.'
Jack spoke to his mother, the GP Dr Clare Bailey Mosley, brothers Alex, 34, and Dan, 30, both management consultants in the City, and sister Kate, 25, a lawyer, about how best to continue his legacy of helping people to improve their health.
The book was born out of that discussion. 'One of the ways was to spread his message through Food Noise,' he says. It became a family project – he planned out the chapters with his mum during a packed train journey through Austria, and she contributed 50 recipes for it.
'I thought I couldn't beat the skinny gene'
Outside of discussions with his father, Jack had developed his own interest in Britain's obesity crisis and weight loss while studying medicine at Newcastle University, where he wrote his dissertation on diabetes with a particular focus on weight loss maintenance.
'One of the things that most interested me is the fact that a poor diet – now the number-one risk factor for early death worldwide – is at the heart of so many chronic diseases,' he says.
Then, while working as a junior doctor, the naturally slim-built Jack experienced first hand how easy it was to pile on weight. He gained 2st 5lb (15kg) in his first year working in a hospital, bringing his weight to 15st 11lb (100kg), which he puts down to stress, over-zealous snacking habits and a lack of exercise.
'I thought I couldn't beat the skinny gene, but it turns out that I could put on weight much more easily than I thought,' he says. 'I was really stressed, as I was trying to work out my place in the hospital – no amount of medical school can teach you what it's actually like to work as a junior doctor.
'The other thing was that I had a long commute in the car. I was driving over an hour there and sometimes more than an hour back home. I got into the habit of munching on sweets in the car. Like my dad, I have a sweet tooth.'
Haribos were a particular vice, as was snacking on chocolate generously gifted by patients and feasting on a family-sized bag of Doritos with salsa on the sofa, which he could get through 'in half an hour'. 'Then, I'd be having these beige lunches with my colleagues – hospital canteens are not known for their good food,' he says.
'I managed to get my first two fillings,' Jack says. 'My fiancée is a dentist, so I wasn't too impressed by that.'
However, he shed the weight quickly after he settled into his job, returned to planning his meals more carefully, started exercising regularly and banned himself from buying large packets of sweets. 'I know I'll just eat the whole thing in an hour, so I'll buy sweets sometimes but a smaller pack,' he adds.
Obesity crisis 'is not a collapse in willpower'
While he is now a healthy weight, Jack is in the minority. More than half the population (64 per cent) are now overweight or obese.
'In the 1960s, 1 or 2 per cent of people in the UK were living with obesity – now it is 30 per cent,' Jack notes. 'This is not a collapse in willpower; there has to be something going on in the environment for this to happen.'
Instead, it's a result of the dramatic change in how we're exposed to food on a daily basis. There has been an explosion in the mass manufacturing of cheap, highly calorific and highly palatable food; snacking (unheard of in the 1960s) has become the norm; and there's a fast food outlet on seemingly every street, as Jack details in the book.
'A lot of people do have good intentions to stick to a healthy diet, but in this food environment, that can be so easily derailed,' he says.
'We're surrounded by foods that are designed to be over-eaten. They're designed to reach the bliss point, where you have this perfect combination of sugar, salt, starchy carbs, fat and flavourings that just sends our brains haywire.
'A lot of these foods are actually really addictive and they light up the pleasure centres in our brain in a similar way that smoking or alcohol do.'
The weight-loss jabs silencing 'food noise'
The term 'food noise' has gained popularity against this backdrop of the obesity crisis and the rise of weight-loss drugs, which work by effectively 'muting' our desire to be constantly eating.
'Food noise is not a scientific term,' Jack notes. 'It refers to your cravings, your internal food monologue. It's that constant chatter about food. It can be that voice that's telling you to grab that extra slice of chocolate cake or packet of crisps, sometimes even when you're not hungry.'
While some people rarely 'hear' food noise, others live with constant thoughts about their next meal, imagining the taste of food and wanting to eat, he says. While food noise is key to our survival – it tells us when we're hungry and need to eat for fuel – it is also the driving force behind overeating, he explains.
'Weight-loss drugs brought the term to prominence because they are so effective at silencing, or at least quietening, that food noise, because they work not just by reducing your appetite but also reducing your cravings,' he says.
He notes that some users have reported not only being drawn to healthier foods but feeling nauseated at the thought of consuming alcohol or their favourite sugary, fatty food.
'I like to look at these drugs like noise-cancelling headphones, so you put them on, you can go about your day, you can ignore the siren call of processed junk,' he says.
'But when you stop the medication, this all comes racing back, so it's really important that you get the right nutritional strategies to quieten that food naturally.'
'I adopt a diet-first approach,' he says. While taking the drugs, and after coming off of them, he recommends following the Mediterranean diet, including plenty of vegetables, protein and fermented food, and exercising regularly, particularly strength-based workouts to maintain and increase muscle mass.
'I think that these medications are for people who are living with obesity and potentially obesity-related diseases,' Jack notes. 'People who are regarded as more of a healthy weight should not be taking these drugs. They're not a cosmetic drug and they're not a drug to get you 'beach body ready'.'
Treating obesity on the front line
Jack has now been a doctor for seven years, starting off in A&E in the north-west of England, and then taking on emergency units in Melbourne and the Australian Outback, before returning to the UK to work as a GP registrar, a role that sees many patients enter the treatment room because of weight-related conditions.
'There is a huge amount of disease related to obesity, and we see them all the time,' he says. 'A lot of primary care is treating these diseases before they become raging infernos.'
Heart disease, Type 2 diabetes, high blood pressure, cancer, obstructive sleep apnoea and dementia are just some of the conditions that are being fuelled by Britain's bulging waistline.
'A lot of these diseases are linked to inflammation, which can be as a result of obesity, poor diet and a lack of exercise,' he explains. 'Inflammation in the body is like a smouldering fire that's just slowly damaging your organs and body over time.'
'There has been a rise in colon cancer, especially in younger people and realistically, that is very likely to be tied to the rise in processed junk foods and all this inflammation going on in the body,' Jack adds.
'Many of these diseases can be prevented by following a healthy lifestyle,' he notes.
Continuing the legacy
Food Noise became an instant Sunday Times bestseller, of which Michael had nine in his lifetime. 'I'm absolutely delighted about that,' Jack says.
'[My mother] was so happy, she was really, really pleased, and it's been really nice to be able to work with her on some of this,' he says.
Looking forward, he plans to keep working part-time as a GP registrar but has his sights on future books and projects related to how we can be living healthier lives.
'I absolutely loved writing this book,' he says. 'I'm thinking about diet and exercise, and even things like sleep. I think that's something that hasn't had enough focus until more recently, especially within medicine itself. We'll see what the future holds.'