A US reality show has been criticised for encouraging obese participants to exert themselves and put their health at risk in order to win a prize.

ABC's Fat March - a US version of Ricochet's Too Big To Walk which aired on Channel 4 in the UK - sees 12 overweight and obese people taking part in a 575-mile walk from Boston to Washington. Each has the opportunity of winning a share of $1.2 million - around £600,000 - if they complete the journey.

One contestant has already quit the show after getting severe pains in her spine, and others were taken to hospital during the 10-week series for dehydration, blisters and foot problems.

Though the group is accompanied by two fitness instructors, health experts have labelled the show dangerous; saying severely obese people - who already face the possibility of heart problems and other conditions - should carry out exercise progressively and carefully.

"This show is dangerous for lots of reasons. It's obviously a terrible idea. It violates everything we know from exercise physiology about a safe, progressive exercise programme," James Rippe, a cardiologist at Tufts University in Boston told USA Today.