Children's fast food meals vastly exceed the amount of energy, salt, sugar and saturated fat children should eat in one meal, according to a damning report from the Cancer Council NSW.
The Fast Food: Exposing the Truth report showed an urgent need to reduce the amount of energy and unhealthy ingredients in fast food meals, the council said.
Its nutrition and program manager, Clare Hughes, said Australians on average spend about a third of their food budget on fast and takeaway food.
"If we are serious about addressing the issue of overweight, obesity and chronic disease in Australia we have to be realistic and say people are eating out of home … so if we can make these unhealthy choices a bit healthier that might make a difference".
But the Australian Food and Grocery Council has criticised the report, saying it relies on out-of-date information and selective benchmarks.
The report analysed 199 different children's meal combinations from six major fast food outlets, finding at worst they contained more than an entire day's salt and saturated fat in the one meal.
"If kids are having a fast food meal they are getting a fair whack of what they should be having in one day, in one meal," Ms Hughes said.
It found 90 per cent of children's meals exceeded the recommended salt levels for four- and eight-year-old children.
About 70 per cent exceeded energy and sugar requirements for four-year-olds, and about 50 per cent for eight-year-olds.
Ms Hughes said the researchers had also recorded more than 1400 meal purchases at 20 fast food outlets, finding that people chose the healthy options on menus less than 1 per cent of the time.
"What that tells us is it is not just about including healthy options," she said. "One of our recommendations is that targets be set for reform of all fast food products."
The report also found about a third of fast food outlets did not have nutritional information available for customers.
In NSW nutrition information is mandatory, but Ms Hughes said a national approach was needed to ensure everyone could access it.
A spokesman for the food and grocery council said the Cancer Council was basing its assessment on a British recommendation that a meal should contain 30 per cent of daily energy and unhealthy nutrients.
"[Our] nutrition criteria is established by accredited practicing dietitians utilising Australian nutrient reference values," he said. "The 30 per cent number being used in this study … has no relevance to Australian dietary guidelines".
He said the majority of the main fast food companies had already completed roll-outs of nutrient information on menu boards, and healthy choices were available.