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.