THE BIGGEST LOSER champion Adriano "Adro" Sarnelli has attacked his obese family for ignoring his offer to help them lose weight.

Mr Sarnelli, 28, dropped 51kilograms from his 145-kilogram frame using the show's controversial hard-core fitness regime. He still sticks to a rigid program of diet and exercise to maintain his slimmed-down figure.

Now a qualified personal trainer, he recently opened a weight loss retreat, The New Me, but says his overweight siblings refuse to attend.

Instead, his sister Stephanie, 22, is having $14,000 lap-band surgery.

Weighing 149kilograms, Ms Sarnelli says she does not have the motivation for boot-camp-style training.

"I go to uni all day and work nights so I don't have time to exercise. I've tried [meal replacement] shakes, I've tried taking out carbs, but the weight drops off and then comes right back on again."

Mr Sarnelli says his parents, two brothers and four sisters blame their genes for weight problems and think he just "got lucky".

"It breaks my heart to think that I can, and have, offered my whole family the program I provide here and the only response I have had is from my older brother Mac who in his first two weeks has dropped an amazing 11.4kilograms.

"My sister on the other hand just eagerly awaits her surgery."

Mr Sarnelli moved from the Central Coast to set up the retreat outside Melbourne in March.

Morbidly obese people attend the $1500-a-week live-in diet, exercise, education and counselling program for two, four, six or 12 weeks. Since March, his clients have lost a total of 316 kilograms, averaging three kilograms each a week.

Many had tried weight-loss surgery, he said.

"Although surgery has helped many people there are numerous others it fails to help, as they just go back to making the same poor lifestyle choices," he said.

"We are focused on teaching our guests the right way to live a healthier, thinner, happier life, by being responsible for their actions."

University of Sydney Professor of Human Nutrition Ian Caterson said about 40 to 70per cent of obesity had a genetic background.

"There is no single gene, it's a multi-gene problem," he said.

NSW Health Minister Reba Meagher announced a $36million obesity strategy this month including public funding of weight-loss surgery.

lhall@sunherald.com.au