Almost 70 per cent of adults in Hunter New England are overweight or obese, research shows.
The data was revealed in an Australian Institute of Health and Welfare (AIHW) report to be released on Wednesday.
"Obesity is not only becoming more common - it's starting earlier and affecting more people over their lifetime," AIHW spokesperson Amy Young said.
"A whole-of-system approach, including healthier environments and improved access to care, will be critical to reversing current trends."
Hunter New England recorded an obesity and overweight rate of 68.7 per cent for people 18 and over for the years 2022 to 2024.
This compared with 59.5 per cent in 2016 and 52.1 per cent in 2006.
Across Australia, 67 per cent of adults (13 million people) and 27 per cent of children aged two to 17 (1.4 million youngsters) were overweight or obese.
University of Newcastle nutrition expert Clare Collins said "this is not good news".
"People are living with more excess weight. It's not getting better," Laureate Professor Collins said.
"It's probably too early to tell any impacts of the GLP-1s."
She said these weight-loss drugs were not widely available until 2025-26.
The data showed the level of fatty tissue in people's bodies, associated with poor health, was getting worse.
Professor Collins said the obesity issue was well known, but "we're not really reacting to it".
She said more needed to be done.
"We've got to watch and see how available the new medications will be. They are improving people's health," she said.
"Anything we can do to support the government to get the price of those medications down will be welcome."
Ms Young said overweight people and those with obesity were "a significant health challenge facing Australia".
She said the increasing rates of these conditions were "affecting people across all age groups".
They had become the "leading risk factor contributing to ill health and death in Australia, overtaking tobacco use".
Abdominal obesity among Australian adults had almost doubled from 25 per cent to 48 per cent from 1995 to 2024.
Ms Young said the causes of obesity and being overweight were complex.
She said many of the factors that drove the conditions were "outside an individual's control, including the environments people live in".
"These factors often disproportionately affect those in lower socioeconomic areas, which contributes to ongoing health inequities," she said.
"The misconception that body weight is simply a matter of personal responsibility overlooks the broader social and environmental drivers of obesity."
In 2023-24, almost $800 million was spent treating obesity in Australia.
A further $10 billion was spent on health conditions attributed to being overweight.
Professor Collins was co-chair of an advisory committee for updated clinical practice guidelines to treat obesity.
They provide recommendations for healthcare professionals about the diagnosis, treatment and management of obesity.
"Even new guidelines will not change things unless we see an activation in care, particularly for people living with obesity," Professor Collins said.
The number of people living with the most severe forms of obesity was increasing.
"That's the concern. That's exactly the group for whom there is now effective treatment [with GLP-1s], but it's expensive," Professor Collins said.
"They're hard to get unless you can afford it, or have type 2 diabetes."
She said bariatric surgery was another effective approach.
Ms Young said lasting change would come from an approach that "prioritises prevention and supports early intervention".
