The biggest independent study to date of packaged food on supermarket shelves has found most of it is unhealthy.
More than two-thirds was classified as "ultra-processed" and half were not foods that are necessary in a person's diet.
Authors of the study are calling on the Government to make improved Health Star Ratings labels compulsory and to set food manufacturers targets to lower salt, sugar and saturated fat.
Both the current and the previous government have opted to work with the food industry to encourage improvements in labelling and reduction in sugar and salt content rather than impose requirements.
But those who conducted the New Zealand State of the Food Supply study say substantial change across the food supply was unlikely without strong government direction.
"We need the Government to take real action by setting targets to lower salt, sugar and saturated fat content," Dr Sally Mackay, a lead author of the report, said.
The study analysed 13,000 packaged food items using the Health Star Rating criteria, which rates foods from 0.5 to 5 stars.
Researchers found that 59 per cent of items have a low star rating and that even in categories such as muesli bars and yoghurts the average rating was low.
Poor diet was the leading cause of early death in New Zealand, accounting for nearly 20 per cent of illnesses and premature death, Mackay said.
"Getting healthier foods on the shelves makes it easier for consumers to make a healthy choice, which is key to curbing the obesity epidemic and diet-related ill health," said Mackay, a research fellow at Auckland University's medical and health sciences faculty.
Although acknowledging that the country's top food manufacturers have made commitments to reduce sugar, salt and fat in their products, the researchers said industry uptake of the Health Star Rating had been too slow at only 21 per cent of eligible products, and all packaged food should be required to carry Health Star labels.
"Consumers have the right to know the healthiness of the products they're buying," Mackay said.
Health Star Ratings are an independent system developed by the New Zealand and Australian governments with public health experts, the food industry and consumer groups. Packaged foods are given a number of stars based on their nutrients, ingredients and the amount of energy (kilojoules) they provide.
Whether to include the star rating on labels is voluntary for food manufacturers.
Health Minister David Clark said the Government was serious about tackling obesity and the health problems that stemmed from too much sugar, fat and salt in our diets.
"We are working on this with the food industry itself through the Food Industry Taskforce. Reformulation of processed food and drink and an improved food labelling system are key strands of this work."
Clark said he was considering advice about the next steps of the taskforce.
When he was in Opposition, Clark criticised the National Government for not pulling corporates into line over the " tsunami of sugar and salt in everyday foods".
An article he authored in 2017 said a " massive flaw" in the voluntary food labelling system meant it could be "rigged" by manufacturers "at the expense of New Zealanders' health".
He said a Labour Government would "look at a front of package labelling system such as the number of teaspoons of added sugar and salt in a product so that people can make clear and informed decisions about their food intake."
Yesterday, Clark said an independent review of the Health Star Rating system had been done and Food Safety Minister Damien O'Connor was leading the work.
A spokeswoman for O'Connor said a report on the rating system was imminent.
The study, done in collaboration with Australian food and health academics, aimed to take a snapshot of what we are currently eating.
Among other key findings:
Fruit and vegetable juices and energy drinks had the highest mean sugar content.
Most breads and cereals had ratings above 3.5 stars. High performers included Goodman Fielder's breads and Nestle's cereals, while Dairyworks had the lowest proportion of ultra-processed products.
Only three companies had an average star rating of 3.5 across their products - Sanitarium, McCain Foods and Sealord.
Healthy Food Guide editor-at-large Niki Bezzant said the findings were no surprise.
"The healthiest food doesn't come in packaging."
Bezzant favours making it mandatory to display health star ratings. "Though not perfect, it would at least give shoppers a quick comparison between products."
There is so much "marketing speak" on packaging that shoppers couldn't be expected to cut through it.
Researchers from a range of fields including public health, medicine and marketing, have said a targeted tax on sugar should be top-priority to tackle the country's interconnected issues with obesity, type 2 diabetes and rotten teeth.
The Labour-led Government has no plans for such a tax.
• 69 per cent of foods were classified as "ultra-processed".
• 13,000 packaged food items were included in the study.
• 79 per cent of breads had a star rating at or above 3.5.
• 68 per cent of breakfast cereals had a star rating at or above 3.5.