Australia is now one of the fattest nations on Earth.

Sixty per cent of us are overweight or obese, and by 2025 that figure will rise to 80 per cent.

Despite this, Australia still has no national obesity strategy.

What we do have are two key federal programs — the Healthy Food Partnership to encourage healthy eating, and the Health Star rating, a front-of-pack labelling system.

But the rules for these two initiatives have been set by committees made up of government and public health advocates, as well as food industry representatives.

According to one insider who spoke to Four Corners, "the reality is that industry is … making most of the policy", and public health advocates are only included "so we can have the least-worst solution".

Companies like Coca-Cola, Pepsico, Unilever, Nestle and Kelloggs have a seat at the table setting the policies that shape consumption of their own sugar-laced products.

As Australia's obesity and diabetes rates continue to soar, public health advocates have told Four Corners the industry has been obstructing and delaying policy outcomes that would lead to better health.

And they have likened their tactics to those deployed by the tobacco industry.

Big sugar's seat at the table

Executive manager of the Obesity Policy Coalition Jane Martin said the food industry shouldn't even be inside the committees setting food policy and regulation.

Jane Martin worked on the Health Star rating system and encountered strong resistance from the food industry. ( ABC News )

"Industry should be consulted around what policies should be implemented, but they shouldn't have a role in deciding what they are," Ms Martin said.

"They should be decided separately based on the evidence and the potential impact, and then industry should be involved in how to make that happen."

Ms Martin was a member of the committee that developed the Health Star rating system, which gives packaged foods a rating of one to five stars depending on how they measure up against other foods in a similar category.

She said food industry representatives fought successfully to scuttle efforts to make that system mandatory.

"I was on the committee for two and a half years, but it moved very slowly," Ms Martin said.

"Some of the key elements that were on the table — such as that the system should be mandatory — ended up being off the table by the time the negotiations closed.

"That's because industry didn't want it to be mandatory, so they took their time, they lobbied behind the scenes and it wasn't made mandatory. That's a big flaw in the system."

The forces blocking a sugar tax

As a former independent member of the ACT Legislative Assembly and former territory health minister, Michael Moore knows how politics works.

And as Public Health Association Australia CEO, he also knows a thing or two about health policy.

"Big industry knows that if you're going to have influence then you're going to have to talk to members [of parliament]," Mr Moore said.

"This is where the influence happens. Industry can put much more into it than public health and consumer voices."

The food and beverages industry is against the introduction of a sugar tax. ( ABC News )

As one of the nation's leading public health advocates, doors open for Mr Moore and politicians give him an ear.

But in the fight for good public health outcomes there are others who stalk the corridors of Parliament House, and they have more to give than just informed advice.

The food and beverages industry spends millions of dollars on political donations, lobbying and duchessing politicians.

When it comes to a sugar tax, the heavy lobbying work has been done by the Beverages Council.

Last month the United Kingdom became the 28th country in the world to introduce a sugar-sweetened beverages tax.

Twenty-eight countries around the world have implemented some kind of sugar tax. ( Twitter: @NCDFREE )

So far, the Beverages Council has been extremely successful in preventing any talk of a tax on sugary drinks becoming a reality in Australia.

In its 2016 Annual Report, the Beverages Council admitted to spending a "vast amount of resources" lobbying against a sugar tax.

The council boasted of its success at "keeping the topic of a tax off the table from both of the major political parties".

The report is no longer available on the Beverage Council's website.

Ms Martin said the health impact of too much sugar in Australians' diets is well known, but there was a good reason why a sugar tax had not gained much traction in Australia.

"It's not that the public aren't on board, the politicians aren't on board," she said.

"The reason that a lot of the politicians aren't on board is because of this influence that we're seeing of groups like the Beverages Council … working against effective recommendations."

'Just like big tobacco'

Ms Martin, who began her public health career fighting tobacco industry-style tactics, said working on the sugary drinks tax issue was like Groundhog Day.

"Even the alliances are similar," she said.

"The tobacco industry worked to set up these alliances with the retailers, with the Australian Association of National Advertisers, with the convenience stores, with industry groups.

"[It's] very similar to this alliance that's working against a health levy on sugary drinks."

Mr Moore also compared the sugar tax issue to the fight against tobacco industry-style tactics.

"What we see is tactics that were used by tobacco being picked up by big food industry, and that's actually what worries us," Mr Moore said.

"It's about obfuscation. It's about delay."

But Geoff Parker, the Beverages Council CEO, forcefully rejected such comparisons.

"There's no safe level of smoking, and so we refute any sort of comparison between what's happening with reducing the prevalence of smoking with reducing the consumption of sugar-sweetened beverages," Mr Parker said.

"They're not the same, and we shouldn't be using that sort of comparison or analogy."

The beverages industry said obesity is a complex problem and blaming sugar alone and imposing on it a discriminatory and regressive tax is not the answer.

Pro-sugar politicians say there is no evidence that a sugar beverages tax works. ( ABC News )

The sugar seats

There is another pragmatic reason why Australia has so steadfastly resisted a sugar tax — the political power of the so-called "sugar seats".

In an era of tight elections, the jobs provided by the sugar industry have guaranteed these seats have extra political weight.

The seat of Page in northern New South Wales is held by the Nationals on just over 2 per cent.

Leichhardt in Far North Queensland is referred to as a bellwether seat usually won by the side that forms government.

Herbert was won by Labor at the last election by just 37 votes.

And the seat of Dawson is held by the maverick LNP backbencher George Christensen on 3.3 per cent.

It's no surprise that Mr Christensen is a fierce supporter of the sugar industry. He believes a tax on sugary drinks would hurt the industry without fixing the obesity problem.

"I would be willing to bet a lot that [a sugar tax] will not do anything in terms of obesity whatsoever," Mr Christensen said.

George Christensen (centre) thinks the focus should be on personal responsibility. ( ABC News: Nick Haggarty )

Mr Christensen has had his own public battle with obesity, but he said it was all his own fault and that personal responsibility is the answer, not a tax.

"I'm a fat bloke, right? I've been fat ever since I was probably about 20, 21. I don't blame the sugar industry. I don't blame Coca-Cola. I don't blame XXXX or Bundaberg Rum.

"I blame myself for putting that product down my gob. That's what caused it — me, myself and I.

"I think that a lot of the issue with obesity has got to come back to telling people that they are personally responsible for the choices they make."

The industry and pro-sugar politicians say there is no evidence that a sugar beverages tax works.

In most cases though, it's still too early to tell if there has been any impact on obesity levels.

But in the UK the tax has already caused some drink companies to reformulate the amount of sugar in drinks.

What is clear is our obesity and diabetes rates continue to climb and Ms Martin says everything we've done so far has failed to have an impact.

"We need to think about what kind of future we want. We have this huge public health problem. The things that we are currently doing are not good enough."

Watch Tipping the Scales: Sugar, Politics and What's Making us Fat on Four Corners at 8.30pm on ABC and iview.