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It's the science behind the diet that's made it Australia's most successful.

Since its release in 2005 the total well-being diet has sold more than 1 million copies- 7 years on CSIRO has reinvented the dietÂ… new menu plans, recipes and tips- making it even easier to get rid of those unwanted kilos.

Bethwyn Boyt Cullis is 28 years old - ten years ago she developed a medical condition and her weight spiralled.

In a matter of months she gained 40 kilos.

"It is hard to keep up with kids, don't want to go out too much don't want to clothes shop but you need new clothes, it effects everything," said Bethwyn.

Sick of countless calorie counting she is trying the new CSIRO diet as a last resort.

"I have had a friend who has had great success on it she has lost 26 kilos and her sister has lost 20 kilos. I have tried tons of other things and they have worked with varying degrees but now it is time to try something new," said Bethwyn.

Her friend is Danielle PhillipsÂ… 26 kilos lighter she is a stay at home mum, turned healthy eating advocate.

"I saw a photo of myself just after I had had my son and it was a family photo and I really looked overweight and unhappy and it should of been the happiest time of our lives two young kids a new baby that is what I wanted my whole life but I still didn't feel happy with myself," said Danielle.

Danielle and her husband Luke underwent a complete life overhaul - cutting out takeaway and excessive carbs for the past two years the CSIRO diet has helped them lose a total of 46 kilos between them.

"My husband has lost 20 kilos and since losing his weight he has joined the army which he wouldn't have been able to do before because he was over one hundred kilos so he has also done really well," said Danielle.

CSIRO food scientist Dr Manny Noakes is the brains behind the diet- she says the key to it's success is the high level of protein which ensures you never go hungry.

"The book is based on more than 20 studies that we have done on the role of the higher protein diet it is also a diet that has been researched by others internationally and we are seeing more and more studies coming out showing the benefit of that protein diet on fat loss," said Dr Noakes.

You're allowed 200 grams of protein for dinner and up to 100grams for lunch.

Throughout the day you can have limited amounts of wholegrain bread, cereal, dairy and fruit and at least 2 cups of vegetables.

"The Total Well Being Diet focuses on loosing fat not losing muscles," said Dr Noakes.

The diet even allows for two servings of indulgence foods a week.

"It is an eating pattern that doesn't exclude any food groups so in that regard the dishes that are in the book could be just as easily prepared for the family as they can be for the person wanting to lose weight," said Dr Noakes.

"I am feeling really good i am feeling positive i am feeling motivated i am feeling on track and i am feeling great," said Bethwyn.

Bethwyn has now been on the diet for a total of 2 weeks - and without exercise she has lost 3 kilos.

"It has been good it has been easy, I haven't had to think about it and the food is great so I am not wanting to come off it for any reason," said Bethwyn.

"I definitely recommend it to anyone if you need to lose weight you have nothing to lose except for the kilos it is just a really good idea and it is a great diet you will end up being addicted to it and stuck on it for life," said Danielle.