The latest data shows the cost of living rose 2 per cent last year — the strongest pace of growth in 3.5 years.
"Broadly, rising cost-of-living pressures are pressuring income-earners across the board," Commsec economist Ryan Felsman said.
He said Australians receiving welfare payments and pensioners were suffering the most.
"What we've seen of course is that some of the poorer cohorts, their living-cost index has risen by 1 per cent in the December quarter to an annualised rate of 2.4 per cent — which is well above the consumer price index in particular," he said.
"And at the same time pensioners and beneficiaries, their living cost indices rose the most."
Charity organisation the Salvation Army said while demand for clothing and shelter had always been strong, more Australians were now showing up on their doorstep simply looking for their next meal.
Salvation Army's Mitchell Evans said at their Sydney's Street Level Mission he was seeing more people coming to them every day for help.
"We're seeing people coming to services like Salvation Army just to eat during the day," he said.
"They've had to pay for bills, they've had to pay for medication, which is all quite costly, and they're having to come to services like us just to eat."
One young couple, May and Ben, said they had been spending increasing amounts of their money on food, rent and transport.
"I never actually left home. I'm trying to move out and it's just too expensive — you can't do it."
May said she was 27 and that about half of her friends were still living at home with their parents.
Both expressed concern about their long-term financial security.
A retired couple from Switzerland, which has the world's highest cost of living, have been making the same trip to Australia for 20 years.
They said Australia was heading in the same direction as their own country.
"Sydney's getting close to Switzerland — everything has become more expensive."
