Key Points:

Snacks, booze and three takeaway meals was all in a day's work for former Shortland Street favourite Karl Burnett.

The 32-year-old, who played Nick Harrison from 1992 to 2005, was obese and had trouble with depression, concentrating and sweating.

Burnett's dreams of strutting down the beach with a six-pack on display seemed out of reach at 120kg - until the former skinny-geek-on-the-Street turned to diet police TV show Downsize Me! for urgent help with his junk and carb addictions.

"Going on the show forced me to lose weight and get off my ass," he said. "Damian [the show's diet guru] said I had the worst diet he'd seen. I ate takeaways out of laziness."

Burnett set an ambitious goal of losing 35kg over the two months the cameras followed his every move.

Thanks to straight-talking trainer Lee-Anne Wann and advice from dietician Damian Kristof - not to mention exercising on the beach in his underpants - the freelance sound engineer dropped about 20kg.

Since filming finished, Burnett has lost several more kilos, is still eating healthily, goes to the gym and is on track to reach his target weight by summer.

He has also learned to control his alcohol intake.

"I don't buy a whole box and sit at home on my own and drink it all now," Burnett said.

"I'm still not where I want to be. I have still got a little bit of a gut but I'm not hugely obese like I was before. I would like to be pretty ripped."

Judging by the schedules, there's a still a huge appetite for shows connected with weight loss. Too Fat To Toddle and I Know What You Ate Last Summer will join Downsize Me! on the spring schedules.

Too Fat to Toddle follows four British families with obese children at a fat camp for under-fives. Professor Paul Gately presents the programme about the UK's ticking timebomb obesity epidemic - a quarter of Poms starting primary school are overweight or obese.

I Know What You Ate Last Summer follows six obese British teens as they binge eat, lie and hide food in their rooms during an eight-week fat camp.

Media commentator Wendyl Nissen believes social trends play a huge part in TV programming.

"Shows always trade on what we relate to," she said. "It's simple, and a matter of picking up and reading trends about what people are thinking.

"It's all freaks and geeks all over again. One year it's the anorexics, the next it's fat people.

"We have such a big obesity problem that the fat shows are going to keep coming for some time, I imagine."

Auckland nutritionist Jacquie Dale said diet shows gave good advice but they set unrealistic expectations for the aver- age Joe Bloggs.

Dale said 95 per cent of people who lost weight quickly put it back on and that a "quick fix" was unsustainable.

"Real-life long-term management or losing weight is making gradual changes," he said. "It's not as difficult as it's played out on TV.

"We seem to think everything has got to be really hard for it to work but people can lose a kilo a week just making small changes.

"Realistically you should only lose 1 per cent of your weight a week."

* I Know What You Ate Last Summer premieres at 1pm on August 30 on TV2. Downsize Me! premieres at 7.30pm on September 2 on TV3. Too Fat To Toddle premieres at 9.30pm on September 3 on TV1.