There are calls to redesign plane, bus and train seats to accommodate modern body sizes.
Australia-first research has revealed the nation gains an average of 1.5 to 3.5 kilograms per person per decade which will have an impact on transport efficiency and safety.
Anticipating changes in body size is important to make sure the design and layout of transport remains fit for use, according to University of South Australia academics who did the study.
The authors cited other research that found airline seat dimensions are problematic and unable to accommodate up to 68 per cent of males and 22 per cent of females because they were based on weight data from the 1950s to 1970s.
The study was conducted for Transport for NSW and Victoria's Department of Transport and Planning, funded by the iMOVE Cooperative Research Centre.
The issue has gained attention in the United States recently after it was revealed United Airlines could save $US 80 million per year if passengers shed an average of 4.5kg each because heavier planes burn more fuel.
iMOVE managing director Ian Christensen said the findings would help ensure transport systems were comfortable and safe.
"It's an opportunity for designers, policymakers and industry leaders to come together and create transport solutions that are inclusive, sustainable, and forward-thinking," Mr Christensen said.
Incorporating the data into the design process would also add to efficiency, Christina Kirsch from Transport for NSW says.
"Our objective is to gain data specific to the Australian population so we can design public transport that caters specifically to our shapes and sizes," she said.
"These designs directly impact passenger comfort, safety, accessibility, and overall user experience."
