Researchers at the George Institute for Global Health analysed more than 34,000 products and found 70 per cent contained added sugars, which they say are simply "empty calories" contributing to Australia's obesity epidemic.

They calculated two health star ratings – one using total sugars (as is current practice) and one using added sugars.

"We know there are problems, anomalies with the ratings system," said co-author Professor Bruce Neal. "But by using added sugars, we found higher ratings were given to good foods and lower ratings to unhealthy foods."

The researchers found discretionary foods such as cakes and chips contained four times more added sugar than core foods such as milk and bread.

The federal government's health star ratings, introduced in 2014, have been heavily criticised for producing inconsistent ratings, confusing shoppers and being riddled with loopholes.

For example, a 290 gram box of Kellogg's Nutri-Grain cereal contains 77 grams of added sugar. Yet, it boasts four health stars.

"There are some cereals that contain high amounts of added sugar and perform unreasonably well," said Professor Neal. "By contrast, dairy products with lots of naturally occurring sugar, considered reasonably healthy, are getting unreasonably low scores."

Nutritionist Dr Rosemary Stanton, who was involved in the early stages of developing the system, said health experts did fight for added sugars to be taken into account, but the food industry pushed back.

She said companies were now "manipulating" the system to get as many positive points as possible.

"It's an absurdity that they didn't use added sugars," she said. "The industry claimed that because added sugars weren't on the label, nobody could check to see if it was the truth."

The Australian Food And Grocery Council told Fairfax Media the project committee made this decision because it believed the algorithm should "stay as close as possible to the FSANZ Nutrient Profile Scoring Criterion in the Food Standards Code, which means total sugars," and the UK Food Standards Agency, which developed the original algorithm, considered and discarded added sugars in favour of total sugars.

Consumer advocacy group Choice said the World Health Organisation and the Australian Dietary Guidelines instructed consumers to limit added sugar intake, but that this was near impossible because of the lack of labelling. They are fighting for added sugars to be clearly labelled.

In its submission to the five-year review of the system, now underway, Choice has called for ratings on fatty, salty and sugary foods to be capped at 2.5 stars, to be mandatory on children's products, and to be used on whole foods, not juices and concentrates.

"We're starting a 'Five Main Asks' campaign and asking consumers to support these changes," said Choice's Katinka Day.

"Another point is that added sugar should be included in the health star calculation."

A federal Health Department spokesman said the Technical Advisory Group assisting the five-year review will consider the issue of added sugar.

It said added sugars are not chemically different to sugars naturally occurring in foods, which makes it difficult to distinguish between added and naturally occurring sugars using analytical methods.

It also said there is no standard method for analysing added sugar content of foods and beverages.

"Sugar labelling is a complex issue. The Australian and New Zealand Ministerial Forum on Food Regulation has recently agreed to a program of work to investigate added sugar labelling," the spokesman said.

"This work will consider consumer understanding and behaviour in relation to sugar labelling, international approaches to sugar labelling plus broader policy considerations in relation to sugar."

Kellogg did not respond to requests for comment.

The George Institute's research is published in Nutrients.

There are at least 42 different names used on food labels for added sugar including sucrose, muscavado and turbinado.

A Choice report found that if consumers could identify added sugars on food packs they could avoid 26 teaspoons of sugar each day and up to 38.3 kilograms a year.

smh.com.au