His weight and poor health once made him feel like he was a “prisoner” in his own body and like he was “always seen as the fat man in the room”.

But now Mark Calvert is getting ready to climb Ben Nevis after dropping nearly seven stone - and turning his back on 20 years of being overweight and fearing for his future.

The 48-year-old’s eating habits caused him to develop type two diabetes, with high blood sugar levels meaning regular visits to the doctors.

He tried hundreds of diets, restricting his calorie intake and cutting out fats - but nothing seemed to work.

“I was a miserable and broken man who in reality was dying,” said Mark, who lives with his wife and children in Woodbridge.

“Something had to change.

“When I was at my heaviest last summer, people would never look me in the eye. I was always seen as the fat man in the room.”

He was desperate and embarrassed when he joined a Slimming World group in July last year.

But it has proved to be the turning point for Mark, as he has not looked back since.

Starting his journey at 21stone 2lbs in July, he now weighs 14stone 6lbs - just 13lbs off his target weight, which he aims to reach by the end of April.

“I’ve lost my eight-year-old granddaughter’s entire body weight and some more,” he said.

“My family are amazed by my results.”

Before the weight loss, Mark said he knew very little about food.

He is now more educated and able to continue eating the food he loves, but in a healthier way.

He added: “I never feel hungry or deprived. I’m always full and, if anything, I’m eating more than I ever have.”

“I’m more active now. I go for walks everyday, I’m being more productive at work and I’m honestly the happiest I’ve been since my early 20s.”

In terms of exercise, Mark aims to walk 10 miles a day - getting up at 4am every morning to go for a long walk before work, and fitting one in during his lunch break.

To celebrate the huge weight loss achievement, Mark is going to climb Ben Nevis in June - but he says the real challenge now is maintaining his weight loss.

“I owe massive gratitude to Lisa Palmer who runs the group,” he said of Slimming World.

“I cannot thank her enough - there is no way I am going back to where I was before.”

Lisa runs two groups in Woodbridge and is opening a second group on Fridays in Martlesham, in addition to her Saturday morning class.

Lisa added: “Mark has totally transformed before our eyes and his confidence now is absolutely amazing.

“Giving someone back their confidence is why I do what I do. There is nothing more rewarding than that.”