The part-time diet

The part-time diet

Part-time diets have gained traction since the release of several new diet books advocating a less-demanding dieting schedule. Rather than counting kilojoules seven days a week, dieters had the option of battling the bulge for just a few days a week.

The 5:2 diet became an instant hit, as it allows normal eating five days a week when paired with two days of fasting. The fasting days don't need to be consecutive, but on those days women can only consume 2092 kilojoules and men, 2510.

According to the website of Michael Mosley, the UK co-author of the bestselling book The Fast Diet, (United Book Distributors, $19.95) following this plan should result in weight loss of a little less than half a kilo a week. Dr Mosley says research also suggests intermittent fasting will result in improvements in blood pressure, cholesterol levels and insulin sensitivity.

Edith Cowan University nutrition and dietetics lecturer Therese O'Sullivan says it may seem radical, but she has an open mind on the diet.

"We don't want to give it the can because it's a bit different. The theory behind this could be potentially a good advance in diet health but it is very early days," Dr O'Sullivan says. The theory of the diet makes sense, as the body is designed to survive for short periods with lower energy intake.

"In these low-kilojoule periods we operate in a repair mode to keep the body in good shape until food is available again," she says.

While more research is needed, Dr O'Sullivan says there are studies to support the health benefits of part-time fasting.

"There have been studies of intermittent fasting in animals, which shows resistance to age-related diseases such as heart disease and cancer and reduction in blood pressure," she says. "This may be potentially due to the way energy and oxygen is metabolised in the body, reducing the cellular stress."

Whether it's the same in humans is unknown, but Dr O'Sullivan is pleased the diet encourages people to keep a record of everything they consume.

If what you're actually eating is a lot of fast food, this diet may not deliver your weight-loss goals.

"There is a risk people will take this as a free-for-all on those five days - it's not a licence to eat junk food for five days."

Dr O'Sullivan says it's also not suitable for people who are underweight, pregnant, breastfeeding, with Type 1 diabetes or insulin dependent.

"It also needs more research before I'd recommend it for anyone," she adds.

If you do want to try it, you should consider how fasting might affect your life.

"You might live longer, but you also might be grumpier - so you may want to ask yourself if that is worth it or not."

Nutrition Australia WA chairwoman Amanda Devine says good nutrition should be about building healthy eating habits and regular meal patterns.

"It's about getting back to eating more vegetables and lean cuts of meat and wholegrains. Getting back to the basics, rather than days when you're starving yourself."