ANDREW 'Cosi' Costello was a contestant on the Biggest Loser in 2008. As controversy rages over the dramatic weight loss of US contestant Rachel Frederickson, Cosi reveals his experience on the show.

Frederickson was crowned the winner of the US version of the show earlier this week after she lost a record-breaking 60 per cent of her total body weight.

Jaws dropped when the 24-year-old unveiled her thin, 105-pound (47kg) frame during the live finale, which aired in the US Tuesday night - a drastic change from when she first appeared weighing 260 pounds (118kg).

Frederickson's 155-pound (71kg) weight loss landed her $250,000 in prize money and also the title of the tiniest US Biggest Loser winner in history.

Today, Cosi writes exclusively for news.com.au about what contestants really have to go through on the hit Channel 10 show:

"The day I flew off to be a contestant on the Biggest Loser, my wife cried at the airport.

I returned more than four months later to discover that she had fallen pregnant the night before I left. So when I got out of the Biggest Loser house, I'd lost a heap of weight and she was carrying a heap more.

Four-and-a-half months is a long time to go without reading a paper, watching TV, driving a car or using money. In fact it's very similar to being in prison, except the inmates are fatter.

When it was the Christmas break, the crew and producers all took 10 days off. Everyone left, everything stopped. So while they enjoyed Christmas with their families, all the contestants sat in the White House with a security guard and supervisor.

We were not allowed to leave the house and we only got five minutes each to call our partners on Christmas Day (we only got to speak to our partners three times during the whole series) It was a very sad and depressing 10 days, but I signed up for the TV show so I can't really complain.

News_Image_File: Cosi auditions for the Biggest Loser in Adelaide in 2008.

You probably think we spent all day everyday working out in the Biggest Loser house. Wrong. No one ever worked out for more than two and a half hours a day. You really can't do much more than that if you're training hard.

Biggest Loser cops a lot of bad publicity about what they do to the contestants. People need to remember that we signed up for a TV show and that's exactly what it is … a TV show.

They want the drama, the tears, the fights, the tears, the triumphs and the tears. Producers would push you to cry because that's what makes good TV. They continually asked questions like "Do you miss your kids?" Needless to say, I broke down more than once.

The only thing that really disappoints me about the Biggest Loser is the length of time between the weigh-ins. Have you ever wondered how the contestants manage to lose a staggering 12 kilos in a single week? We don't. In my series a weekly weigh-in was NEVER filmed after just one week of working out. In fact the longest gap from one weigh-in to the next was three and a half weeks. That's 25 days between weigh-ins, not seven. That "week" I lost more than nine kilos. I had to stand on the scales and was asked to say the line, "wow, it's a great result, I've worked really hard this week". The producers made sure that we never gave this secret away, because if we did, it created a nightmare for them in the editing suite. The shortest gap from weigh-in to weigh-in during our series was 16 days. That's a fact. The thing is, overweight people get inspired by watching the Biggest Loser. They get off the couch and they hit the gym. But after a week in the real world, some people might only lose 1kg so they feel like they've failed and they give up.

That's where the show is misleading. You need to remember it's a TV show, it's not all real. In fact, not even the scales we stood on were real.

News_Image_File: Cosi with Shannan Ponton and Michelle Bridges.

What was real was the passion and kindness shown by trainers Michelle Bridges and Shannan Ponton. These two regularly came in on weekends to take us for extra sessions and they legitimately cared about each of us. They are very good people.

The Biggest Loser finale was an interesting event. I like to tell people it's similar to giving birth … it was long, drawn out and painful. The filming for the final episode took 12 hours. Before going on stage, there was a person behind the scenes whose job it was to help gaffer tape any "flabby" bits of skin. There's a tip for brides to be, nothing makes your tummy look thinner than tightly wrapped gaffer around the body. I refused to use the gaffer tape, but most of the other contestants had their stomachs and arms taped tight.

News_Image_File: Cosi in Adelaide's Central Markets with his family recently. Photo: John Kruger

I would say that about 75 per cent of the contestants from my series in 2008 are back to their starting weight. About 25 per cent had had gastric banding or surgery. I sit in the middle somewhere. I lost 50 kgs, but have put 25 kgs back on since the show and my lifelong battle with weight continues. Anyone can lose weight in a controlled environment; I'd say it's almost impossible not to lose weight on the Biggest Loser.

But the show doesn't address the reasons why people like me are so obsessed and addicted to eating excess amounts of food; it doesn't get to the root of the problem. If any TV producers can work that out let me know, I'd love to go on your show!

You can read more about Cosi's weight loss battle, stories on marriage and fatherhood and his travels around South Australia on his Facebook page.

News_Rich_Media: Channel Ten's Biggest Loser 2014 preview.

Originally published as Secrets behind The Biggest Loser