Without action on obesity, the economic burden of treating obesity-related diseases is estimated to rise from $US9 billion in 2014 to $US17 billion in 2025.

The annual cost of treating obesity-related diseases is estimated to cost Australia $21 billion by 2025, according to new expert estimates.

Obesity is one of the leading causes driving the high rates of heart disease and diabetes and has been linked to many types of cancer.

Without action on obesity, the annual global medical cost of treating these serious health consequences will reach $US11.2 trillion per year within the next eight years, warns the World Obesity Federation (WOF).

According to new figures released by the WOF, the US faces the biggest treatment bill, with a rise from $US325b per year in 2014 to $US555b in 2025.

Australia faces a significant increase, with the economic burden of obesity to rise from $US9 billion ($A12 billion) to $US17 billion ($A22 billion).

"The annual medical costs of treating the consequences of obesity such as diabetes and heart disease is truly alarming," says Professor Ian Caterson, President of the World Obesity Federation.

"Continual surveillance by WOF has shown how obesity prevalence has risen dramatically over the past 10 years and with an estimated 177 million adults suffering severe obesity by 2025, it is clear that governments need to act now to reduce this burden on their national economies."

The percentage of Australian adult men and women living with obesity was around 27 per cent three years ago. Based on current trends, that figure will rise to 34 per cent in eight years time.

Experts from the WOF say spending more on treating and preventing obesity will save countries many millions in the long term.

Its a call echoed by the head of the Royal Australian College of General Practitioners (RACGP), Dr Bastian Seidel.

"We've been very clear in terms of what we need to be doing. Firstly we need to actually talk about how we advocate for better treatment options for treating obesity," said Dr Seidel.

He says this includes more cost-effective medications and better access to bariatric surgery.

"There is mediation out there but its not listed on the PBS, so there is significant costs involved if patients want to access those tablets," Dr Seidel told AAP.

"Looking at bariatric surgery, again its been quite limited. The public system certainly can't cope, there are waiting times that are completely unacceptable and certainly the access there needs to be improved."

Secondly, targeted training for all medical professional and even teachers in schools and community centres is needed, says Dr Seidel.

"We need to focus on nutrition, we need to focus on physical activity, we need to focus on obesity prevention," he said.