Starts Monday, November 6th on Channel 4

Eight seriously obese people have been given an extraordinary chance to lose weight, get fit and change their lives in a marathon 500-mile walk from the south coast of England to Edinburgh.

The four men and four women are aged between 20 and 44 and come from across the country. Their weights of up to 32 stones are not only making them unhappy, but also putting their lives at risk.

They have a range of reasons for taking part: Gary’s doctor told him that if he didn’t lose weight he risked not being around to see his kids grow up; Stacey wants to be an airhostess, but can’t even fit in airline seats; while Jack hopes that losing weight will give him the confidence to stop hiding himself away and get life a lad his age should have, going to clubs and having girlfriends.

But it’s going to be a huge lifestyle change for the walkers, who are more used to comfort-eating on their sofas than hiking in all weathers. And despite help and advice from experts at the start, it’s down to them to find the physical and emotional strength to complete this amazing challenge.

The eight-week trip will be an incredible journey for all of the participants. Not only do they face up to twelve hours of walking a day, but they will also need to stick to a new eating plan. And on top of that, they’ll have to get along with, and support, their fellow walkers as they share tents camping along the way.

The march comes as Britain faces an obesity epidemic; half of the population are overweight and a fifth are clinically obese, risking early deaths.

Losing weight should be straightforward: eat fewer bad foods and do more exercise. Yet many experts believe that there are psychological as well as physiological factors stopping people from getting thin and staying that way.

How will the walkers get on, and can they provide a radical solution to their own and others problems?