The World Health Organisation (WHO) has released research showing Australia is the only country in the world where childhood obesity rates have overtaken adult rates.
The number of overweight and obese children has doubled since 1985, with 23 per cent of all Australians under 16 now fitting into the two categories.
Obesity experts Professor Ian Caterson from Sydney University and Paul Zimmet from Monash University have labelled the figures a tragedy for Australia.
Prof Caterson, who will address the Chronic Diseases Summit in Canberra tomorrow, said he was particularly concerned by statistics showing people aged 20 to 35 were gaining weight the fastest.
"Our worry is that if our kids are getting fat quicker and people in their 20s to 30s are getting fat faster (than the previous generation), when they're middle aged we're going to have a real problem," he told AAP.
The academics support calls by US-based WHO researcher Professor Barry Popkin to institute a so-called calorie tax on manufacturers to lift the price of unhealthy food.
But they said it may be even more effective to subsidise fresh food to make fruit and vegetables cheaper.
"Over the last few years, the things we want people to eat have gone up in price more than processed food," Prof Caterson said.
"So if we make them cheaper, we're rewarding people for eating the right things rather than punishing them for eating the wrong things."
He said while eating habits were largely ingrained, (no pun intended) research had proved that price affects what people buy.
One study showed that halving the price of apples boosted sales three fold.
Prices would need to come down substantially through subsidies offered either to growers, transporters or supermarkets by both state and federal governments, Prof Caterson said.
The move would bring the price of fresh produce back into line with processed foods and get fruit and vegetables to people quicker and fresher.
The experts will tackle Australia's childhood obesity epidemic at the International Congress on Obesity in Sydney next month.
"We live in an affluent society and Australian children are now suffering from 'affluenza'," Prof Caterson said.
"Preventing obesity is a better way of reducing chronic disease and simpler because you can do it with eating and lifestyle intervention."