A tea and a scone is perhaps not as healthy as first thought – not when it rates lower on the Health Star Rating system than KFC chicken and chips.

The Health Star Rating system, adopted by both the New Zealand and Australian Governments, rates KFC chicken three and a half health stars. The chips score four and half stars.

The rating system is a voluntary front of pack labelling system, that uses a scale of half a star to five stars to communicate “the more stars the healthier,” the system’s slogan.

The Ministry for Primary Industries says the system, released in 2014, is about making it quicker and easier for consumers to make better-informed, healthy food choices.

However, fries from KFC, Burger King, McDonald's, Carl's Jr. and Pizza Hut all rate towards the higher end of the scale with three and half to four health stars.

Both a cup of tea and a plain scone rate only two health stars, while a cappuccino and a blueberry muffin come in slightly higher, rating of two and half stars.

MORE: Claire Deeks: Healthy food star ratings have to go

Elaine Rush, Professor of Nutrition at AUT and registered nutritionist specialising in public health nutrition, said the fact that the fries are made from potato gives them one whole star extra and they also have a reasonable amount of fibre.

“I really wonder about fries being counted as a vegetable. They are pretty high in calories too.”

Food Safety Minister Jo Goodhew said the current system has been developed for packaged food and “it is not appropriate to apply it to restaurant foods.”

Fruit juice also gets four stars, which Professor Rush said is an anomaly.

“We know that fruit juice, a small glass, can replace one of your fruits, but the sugar in it, even though it’s natural sugar, is not good for children’s teeth so it’s not something we would be advocating to feed growing children on a regular basis. They would be much better off with water and milk.”

Professor Rush said the system is causing the food industry to take some notice of it and they can use it as a marketing ploy to reformulate some foods.

“If you change the recipe for a food you can actually change the health star rating. A food like a TV meal could easily go up a couple of stars if it had more vegetables and less of a high calorie sauce on it.”

Registered dietician Dr Caryn Zinn said a serious flaw of the system is the fact that it’s voluntary.

“If you had a terrible product you wouldn’t opt for [the star rating label].”

The unhealthiest products on the system are ones such as soft drinks, ranking one star. Most cereals rank around two and a half. The healthiest, five-star products include trim milk and plain yoghurt.

Professor Rush said fruit and vegetables have five stars by default but within that there are some that would be better than others to have more of.

“Avocados are an excellent fruit but they are very high in calories so mix that with other fruits, looking for a variety of fruits and vegetables within that category not just a single fruit.”

She said it’s all about eating the right amount of things and not just eating it all the time because it has a five star rating.

New Zealand Food and Grocery Council CEO Katherine Rich said the system has not been developed for fresh fruit and vegetables, “which New Zealanders already know are healthy.

“If someone needs a Health Star Rating on carrots and apples to tell them they are a healthy choice there is a more serious educational issue that labelling can’t fix,” she said.

Ms Rich said the system is one of the most credible labelling systems used around the world.

“HSR is a pragmatic, easy-to-interpret system that’s backed by government, the Ministry of Health, the food industry and public health groups,” said Ms Rich.

“Consumers can see at a glance exactly what’s in a product, while the introduction of HSR is furthering the extensive work in the industry to remove sugar, salt and fat so they can achieve even higher star ratings to better help shoppers make healthier choices.”

New Zealand companies have been slow to take up the voluntary ratings system, however the best aisle to compare products is the breakfast food aisle.

All of Sanitarium and Kellogg's cereal products have the health star ratings on their packaging, including Kellog’s Crispix with one and a half stars through to All Bran and Sanitarium’s Weetbix with five health stars.

Sanitarium was part of the working group associated with the initiative’s development and was one of the first companies to publicly get behind the Health Star Rating system.

Sanitarium Health and Wellbeing executive general manager Pierre van Heerden said the company always advocated consumers’ choice and the research was quite clear that this was the best system to use, as “it doesn’t just look at one nutrient but the food as a whole.”

“The system is about looking at food with a holistic view rather than reductionist view. If you put a label on an apple, it would not rate so well because of the sugar, but it’s natural sugar.

Sanitarium always look at how they can improve their products that aren’t five stars, said Mr van Heerden.

“We are constantly reformulating to them be healthier and tastier.”

Mr van Heerden said nothing has been removed from the nutritional panel, the stars provided extra information.

“The government and industry should be applauded for supplying more information to consumers.”

He also said the only reason the star rating labels are not on more products is because companies are bringing these out with their next run of packaging and most companies order in bulk lots.

Ms Rich said: “The whole point of HSR is to help people make healthier choices when comparing foods within the same category.”

The Ministry for Primary Industries however, said the system does work across food categories but there could be inconsistencies.

For example, a full-fat Greek yoghurt receives fewer health stars than liquorice confectionery.

Dr Zinn said the health star rating system makes it seem that processed packaged foods are being endorsed.

“It is really serious because if health professionals are seeing flaws it’s just going to make everyone confused.”

She said it was “ludicrous” that full fat milk would rate lower than packaged processed foods.

“They shouldn’t even rate packaged foods at all. It sends a message that these foods are good for you, rather than better than others in the same category.”

Professor Rush said: “It’s not perfect, but no system is. Food is so complicated; to think you could boil it down to a health star rating is naïve. It is a way of judging one food against another.

“That is the other thing, its rated per 100g you don’t eat 100g of every food. Portion size matters a lot as well. It is just one part of assessing the nutrient density.”

Artificial colours, flavours, additives, preservatives and sweeteners are not considered in the Health Star calculator.

The Health Star Rating system is scheduled to be reviewed this year and then again in 2019.