Geoff Whitington, 63, from Ashford, Kent, was made so sick by obesity-related type 2 diabetes that he had been told he may need a leg amputated . It is a toe-curling moment that many have faced: the supermarket tantrum. And Geoff Whitington, pouting and shouting, performs it with aplomb. 'I don't want to!' is the cry when he is asked if he will try whelks. Despite the wobbly bottom lip and huffy, crossed arms, Geoff happens to be a 63-year-old father of four grown-up children. And in this bizarre episode of role-reversal, it is his sons, Anthony and Ian, who are gently – some might say valiantly – trying to broaden his palate. The problem will be all too familiar to anyone who has broached the subject of healthier eating with a parent who might not have the most up-to-date ideas about diet. But the Whitington boys are motivated by a matter of life and death. For years, Geoff was ill, made so sick by obesity-related type 2 diabetes that he had been told he may need a leg amputated. Turning round his health would mean changing the habits of a lifetime of poor food choices and no exercise. And Geoff resisted with a passion. While many would have admitted defeat in the face of his almost insurmountable stubbornness, the two brothers overhauled their father's health, and crucially, his attitude. And in doing so, they have undoubtedly saved his life. Anthony and Ian have helped their father shed six stone and now, two years after that tantrum in the supermarket, Geoff is a man transformed. He loves to cycle, never eats take-aways and counts kale and couscous among his favourite foods. Most remarkably, doctors say he is no longer diabetic – and he is off medication. The supermarket stand-off was caught on camera for a forthcoming film called Fixing Dad, a searingly honest but moving account of the Whitingtons' journey, which has already won coveted slots at film festivals. The brothers have a lifelong passion for film – Ian, 35, is a full-time film-maker – so they decided to document their battle to inspire others to do the same. Anthony, 37, says: 'He wasn't old, but Dad had given up on himself. He blamed himself for his illness but didn't think he could do anything about it. Getting a grown man to change his ways is difficult and there were times when it felt like it was pointless, but we knew we had to carry on. Just the thought of losing him spurred us on.' Luckily for Geoff, his sons are just as stubborn as he used to be, and their plan has been a huge success. 'The difference in Dad is incredible and he is proof that it's never too late,' says Anthony, a father-of-four from Ashford, Kent. 'Physically, he's gone from having to use crutches to get around to taking on 100-mile cycle challenges. Mentally he's a new person – he had retreated into himself and was probably depressed.' Scroll down for video . His sons Anthony and Ian (right) helped the father-of-four shed six stone and overhauled his health . He turned his life around and remarkably, doctors say he is no longer diabetic – and he is off medication . Geoff, who lives in Ashford with second wife Marilyn, works 15-hour night shifts as a security guard. Before his sons intervened, his exercise routine was non-existent and he tipped the scales at 20 stone. He existed on a high-fat, high-sugar diet. Sometimes he'd eat three takeaway meals a day. Anthony, a corporate financial adviser, says: 'He had an old-fashioned mentality that cooking was a woman's domain, so he'd opt for something convenient and quick. Marilyn would cook him healthy dinners but Dad would sneak in a takeaway on the way home.' Geoff's weight problems were worrying enough, but there was the added complication of his type 2 diabetes, which affects more than 2.7 million Britons. If left untreated, the condition can leave a person up to five times more likely to develop heart disease or have a stroke, and at risk of foot problems due to nerve damage and poor circulation. Rates of type 2 diabetes are soaring due to increasing obesity, unhealthy diets, a lack of exercise and an ageing population. Geoff was first diagnosed with diabetes in 2003. But it wasn't until a visit to a podiatrist in August 2013 that the gravity of his situation was laid bare. 'Dad had an ulcer that was giving him a lot of discomfort,' Anthony says. 'He was having to use crutches and going to have the ulcer cleaned and dressed on a regular basis. 'Things had got so bad that the podiatrist told Dad there was a risk he might lose his leg if he carried on as he was. Until then, in his mind having diabetes was just popping a few more pills in addition to ones he was already on for his high blood pressure and cholesterol. This was the wake-up call we all needed.' He now loves to cycle, never eats take-aways and counts kale and couscous among his favourite foods . Anthony and Ian knew drastic action was needed. 'Dad obviously had weight issues which we'd talked about in the past, but we had busy lives so didn't really push it as far as we could have done,' says Anthony. Step one was to overhaul Geoff's diet. Out went the convenience foods and in came a strict two-month, 800 calorie-a-day diet under the watchful eye of professor Roy Taylor at Newcastle University. He is conducting a study, funded by charity Diabetes UK, which aims to see if a low-calorie diet can permanently reverse type 2 diabetes. Step two was to encourage Geoff to be more active, to improve his fitness and outlook on life. 'We wanted him to find a social life and hobby other than work and food – we've done everything from fishing to t'ai chi,' Anthony says. 'But we knew he had to take up an achievable form of exercise that didn't put pressure on his foot, so cycling became a big part of his regime.' He adds: 'Of course there were rows, especially when he was on the low-calorie diet. He'd enjoyed food in the past, but it was the wrong food and here we were telling him it was no good for him, and he had to cook dishes from scratch. 'It's a fine balance taking on an almost parental role with your own dad. We had to be encouraging, but firm, without him feeling he was being bullied into anything.' That's where the filming proved so useful. Anthony explains: 'Filming the whole process meant we could show him footage from a couple of weeks before as a motivator so he could see how far he'd come.' In February last year, the sons took their father on a ten-day cycling trip to Spain. Geoff also tried out a sky-dive simulator (he's planning to do one for real later this year), and tackled rock-climbing. 'He'd spent almost four decades doing soul-destroying night shifts, eating large amounts of processed food and doing no exercise. 'We wanted to inspire him, to show him how great life could be,' Anthony says. 'While the weight loss is fantastic, what is really amazing is his new self-confidence , his self-belief and his love of life.' Step three was transforming Geoff into a diabetes champion, so he could convince others to turn their lives around. Now a trimmer 14 stone, Geoff has taken part in the Prudential 100-mile cycle race, spoken at medical conferences throughout Europe and stopped his diabetes in its tracks. At the most recent meeting with his consultant, he was told he is diabetes-free. Geoff believes the doctors had been 'too nice for too long', and wishes they had been tougher on him. 'I'm just so cross I lived for so long with such a bad quality of life, depressed and basically killing myself. Hopefully my transformation can inspire others too.' Fixing Geoff's diabetes has brought the family closer, says Anthony. 'We went to Scotland over Christmas and Dad was out walking with the grandchildren, which would have been almost impossible two years ago. The kids love having a grandad who is active, and we've got our old dad back.' For more information, go to diabetes.co.uk. To watch the trailer for Fixing Dad, go to fixingdad.com.
Geoff Whitington, 63, had diabetes and was on the verge of losing a leg . His sons Anthony and Ian helped the father-of-four shed six stone . He now loves to cycle, never eats take-aways and chooses healthy options . Doctors Mr Whitington is no longer diabetic – and he is off medication .