GROSSLY overweight, out of condition and addicted to junk food. This year's Biggest Loser contestants were a sorry bunch when their weight loss ''journey'' began screening a fortnight ago. Many tipped the scales at more than 170 kilograms.
Now, just weeks after taking up exercise, participants in Channel Ten's hit weight loss show are preparing for a marathon.
In a move that has horrified sports physicians, contestants will tackle the gruelling 42 kilometre road race after only 11 weeks of training.
The marathon is expected to provide a dramatic end to the show's fifth series as all eliminated contestants will be eligible to compete, the two fastest finishers re-entering the game for one last chance at the Biggest Loser title and its $200,000 prize.
Health experts have warned the inexperienced participants risk a heart attack or long-term health problems if they attempt a distance roughly equivalent to running from Melbourne to Frankston.
Sports medicine expert Peter Brukner said to safely prepare for a marathon they should be training for up to a year.
''All these people are obese, presumably a lot of them have got cardiovascular risk factors, high cholesterol, smoking, high blood pressure … There is a risk of an acute cardiovascular event like a heart attack … The thought of them going from nought to a marathon in 11 weeks is just crazy,'' Dr Brukner said.
Shannon Bourke, the show's heaviest contestant at 214 kilograms, collapsed attempting a four-kilometre run in the first challenge of the series. Doctors discovered the Epping man had fractures in both legs and possible shin splints.
Victorian Institute of Sport medical co-ordinator, Dr Peter Harcourt, warned that attempting a marathon without appropriate preparation could lead to musculoskeletal problems, inflamed joints and acute stress fractures, particularly if runners were overweight.
The concerns come amid allegations that the show's producers are misleading viewers by claiming contestants have lost up to 17 kilograms in a week. There are fears viewers may try to emulate the results instead of aiming for healthy weight loss, considered to be between 0.5 and one kilogram per week.
Dr Leon Massage, who runs a private weight loss clinic, said he had treated a former Biggest Loser contestant who told him weigh-ins - presented on the show as weekly events - could actually take place several weeks apart.
''I think they're trying to impress the audience with the degree of weight loss … They create unreal expectations for the people who are watching it who think that it [weight loss] is weekly … I can't imagine that someone would lose 17 kilos in a week without doing damage to themselves,'' Dr Massage said.
When asked by The Sunday Age if weigh-ins were conducted weekly, the show's executive producer Richard Campbell said: ''I don't want to comment on that.''
Channel Ten has promoted the show's fifth season as one that helps not only contestants but also viewers lose weight through weekly ''Masterclass'' episodes in which healthy eating and exercise tips are provided.
But the network has come under fire for an episode last week in which Victorian Caitlin Bottrell - who had a starting weight of 179 kilograms and was said to have lost 15 kilograms in her first week - vomited three times while training with NSW rugby union team the Waratahs.
Cheering her on, Biggest Loser trainer Michelle Bridges was filmed saying: ''I pay respect to anyone that can puke, get up and get on with it.''
Dr Massage believes it set a dangerous example. ''It's a disgrace. The aim of exercise is not to get them sick and make it painful. If you are [vomiting] your body's telling you something … I'm concerned that [viewers] may be led to believe that there is a necessity to exercise themselves to exhaustion or potentially do harm to themselves in order to succeed.''
Mr Campbell insisted no one will be forced to take part in the marathon, which he said would take place in the 11th or 12th week of the 12-week series.
The remaining competitors won't be required to take part to stay in the game but can compete if they wish. Only eliminated players will need to place well to have a shot at the finale.
Channel Ten says the show began filming in October, which means the marathon should have been in January - after 12 weeks. But a spokeswoman said the marathon had not yet been run, suggesting the ''12 week'' program may stretch longer in reality.