A NEW diet where calorie intake is cut to a quarter of the recommended daily intake for two days a week could be more effective than simply reducing calories over a whole diet.
The 5:2 diet or Fast Diet stipulates that men eat 2500 kilojoules and women eat 2100 kilojoules on two non-consecutive days a week.
It does not specify what can and can't be eaten as long as the dieter keeps to this limit and then eats sensibly for the remaining five days.
Typically for women, breakfast might be two eggs and a small portion of smoked salmon and another meal of grilled chicken and steamed vegetables.
Professor Tim Gill, associate professor and principal research fellow at the Boden institute of obesity, nutrition, exercise and eating disorders at the University of Sydney, said it was a mechanism for reducing total calorie intake that might work for some people.
''There's no magic, no suggestion of any physiological advantage. The theory is that if you reduce intake constantly then the body adapts but for 12 or 16 hours in the day we aren't eating anyway … I don't think it is a panacea but it is a way of structuring calorie reduction for some people. I see it as more of a male thing, men like structure. If every diet worked for everyone we would only ever have had one diet.''
The diet was the subject of a BBC documentary, which will be screened here later this year on SBS.
Professor Amanda Sainsbury-Salis also from the university's Boden institute said she did not consider the diet a fad and that it was more of a new movement in weight management and health improvement. ''There is some evidence that variations in intake can result in some improved health outcomes but we need to do more research into what is best in terms of timing.''
She said it was important to have medical supervision for severe calorie reduction, which could result in some problems such as gall stones.
Dr Rosemary Stanton, a visiting fellow of the medical school at the University of NSW, said the diet might help some people to actually realise what it felt like to be hungry.
''I see people who eat in case they get hungry,'' she said.
''If someone wants to do this I don't have a problem but they would need to realise they can't go crazy on the non-diet days.''