Forty-nine-year-old Paul Mason is Britain's Fattest Man. Estimated to be between 60 to 70 stone, Paul's addiction to food has changed his life forever. He's been bed bound for the best part of a decade, disowned by his family, and turned down for the only thing that can save him - an operation to staple his stomach.

But unable to look after himself, and imprisoned in his own home, Paul's care is costing the Department of Social Services a massive £2,000 a week, and the authorities agree to review his case. Doctors have given Paul just a few years to live, so for him surgery is his one and only hope, not just of staying alive, but of fulfilling his ultimate dream - to walk again. Filmed for over a year, this documentary follows Paul's incredible journey.

Paul is referred to Shaw Somers, one of the UK's leading bariatric surgeons, who faces a minefield of complications before he can decide if surgery is even possible. No one knows exactly how much Paul weighs, and this alone poses logistical and technological problems.

As the NHS consider hiring a Chinook helicopter to airlift him, the tabloids get hold of Paul's story, branding him the World's Fattest Man and thrusting him to the forefront of one of most contentious debates facing the health service today - should the morbidly obese be entitled to taxpayer funded treatment on the NHS, and if not what are the alternatives?

According to the Department of Health, obesity is one of the biggest health challenges we face in the UK. Although Paul is an extreme case of the super obese, he situation is likely to become more common. Currently almost one in four adults and one in six children in England are obese, and the UK is already the fattest nation in Europe. If the obesity epidemic continues at this rate, by 2025 nearly half of men and a third of women will be clinically obese.

Bariatric surgery is on the rapid increase with a 40% rise in operations between 2007 and 2008 alone. As one of the UK's top bariatric surgeons Shaw is well placed to comment on the obesity epidemic sweeping the nation. He believes it could break the NHS.

With the paparazzi camped outside and the debate raging around him, Paul's future hangs in the balance. An attempt to reach out to his family is rebuffed, and even if he gets the surgery he needs he only stands a 50/50 chance of survival. Suddenly, Paul's dream of walking again looks a mile off.