Three of the gravest dangers facing human beings on the planet right now are not separate, disconnected hazards, but manifestations of a single common threat never previously discerned, scientists claim.

An international team of more than 40 experts has identified what it calls "The Global Syndemic": three interconnected health pandemics effectively orchestrated by the shadowy manipulations and influence of vested commercial interests – an entity collectively defined as "Big Food".

Between them, researchers say the linked interplay of obesity, undernutrition, and climate change constitute the most severe known threat to human and planetary health, representing the "paramount challenge" for our species and the environment.

Ordinarily, these public health dangers are viewed as separate, even opposing problems, but the authors of the new report insist otherwise.

"Until now, undernutrition and obesity have been seen as polar opposites of either too few or too many calories," says global health scientist Boyd Swinburn from the University of Auckland.

"In reality, they are both driven by the same unhealthy, inequitable food systems, underpinned by the same political economy that is single-focused on economic growth, and ignores the negative health and equity outcomes."

The 'environmental science' of climate change is again often considered at a remove from the 'health science' of nutrition and food policy – but in a broader context, the links between the food we eat and the systems that produce it are a growing area of concern for researchers, and with good reason.

"Climate change has the same story of profits and power ignoring the environmental damage caused by current food systems, transportation, urban design and land use," Swinburn says.

"Joining the three pandemics together as The Global Syndemic allows us to consider common drivers and shared solutions, with the aim of breaking decades of policy inertia."

The research team – co-chaired by Swinburn and obesity prevention researcher William Dietz from George Washington University – began investigating their project three years ago, initially with a sole mandate to explore the drivers of obesity.

It was only when they zoomed out on the seemingly intractable nature of the dilemma that the bigger, over-arching issue – The Global Syndemic – came into focus.

When they reframed the problem, the sad fact of obesity's ever-growing prevalence in society became easier to understand.

"No country has successfully reversed its epidemic because the systemic and institutional drivers of obesity remain largely unabated," the authors write in their report.

According to the researchers, this is because even when governments endorse policy recommendations to halt and reverse obesity rates, their efforts don't translate into meaningful or measurable change because of what they call 'policy inertia'.

Partially, that inertia results from inadequate political leadership, and partially from a lack of public demand for change. But we also can't deny the strong influence wielded by Big Food players, the researchers say, which acts in constant opposition to any changes in the status quo.

"The similarities with Big Tobacco lie in the damage they induce and the behaviours of the corporations that profit from them," says Dietz, who, along with his co-authors, advocates for a global treaty to restrict the power and influence of the food industry in government policy-making.

"A Framework Convention on Food Systems would help empower individual nations against vested commercial interests, redirect the vast subsidies that currently benefit unhealthy industries, and provide full transparency."

In addition to redesigning economic incentives, the researchers call for the establishment of a US$1 billion fund to support social movements demanding policy action.

But perhaps most importantly, they say it's time we start rethinking how we view these health pandemics: not as separate things, but as a common, linked problem, ultimately backed by giant companies that don't have our health interests at heart, nor the planet's.

"At current trajectories of economic development, population growth, and food provision, it is estimated that by 2050 overall demand for food and animal-based food will increase by 50 percent and 70 percent, respectively, with further destabilising effects of deforestation, species extinction, and climate change acceleration," an editorial commentary on the research, published by The Lancet, explains.

It's a provocative line of argument – and follows on directly from related research recently published in The Lancet, which made the case for just how radically global diets will need to shift in order to sustainably feed the world in about three decades' time.

Of course, not everybody agrees with the villainous characterisation of Big Food's key players; specifically, disagreement comes from their spokespersons.

"Only those with the most extreme of viewpoints could believe that denying our industry a seat at the policymaking table would help to improve diets and nutrition," Tim Rycroft, the COO of the UK Food and Drink Federation, told CNBC.

Similar positions on the new paper were taken up by the Washington-based International Council of Beverages Associations, and by Coca-Cola.

The researchers say this resistance to their conclusions is unnecessary, even if it's not at all unexpected, given their findings.

"We're not trying to put the food industry out of business," one of the authors, food policy researcher Corinna Hawkes from City, University of London, told Bloomberg.

"We want it to exist, but we want it to exist in a different way."

It's not altogether clear where we go for here, but the sweeping new report offers no shortage of recommendations and strategies for governments and decision-makers paying attention.

In any case, it's clear something has to change – and fast.

"What we're doing now is unsustainable," Dietz told media on a conference call to discuss the new findings.

"The only thing we can hope is that a sense of urgency will permeate. We're running out of time."

The findings are reported in The Lancet.