Obesity has been on the rise for some 40 years and will continue to rise for 40 more if governments around the world do not take decisive, policy-driven action, according to Deakin University obesity experts.

Researchers with Deakin’s WHO Collaborating Centre for Obesity Prevention Professor Boyd Swinburn and Dr Gary Sacks, and their colleagues, have mapped the rising obesity epidemic over the past 40 years for the first of four papers to be published in The Lancet Obesity Series, ahead of the first-ever UN High-Level meeting on non-communicable diseases in September.

They point to policy-led solutions as the most effective way to reverse obesity.

“Governments have largely abdicated the responsibility for addressing obesity to individuals, the private sector, and non-governmental organisations,” the researchers argue. “Yet the obesity epidemic will not be reversed without government leadership, regulation, and investment in programs, monitoring, and research.”

The researchers pinpoint the obesity epidemic as beginning in most high-income countries in the 1970s and 1980s.

“In the first half of the 20th century, the population was exercising less, due to increased mechanisation and motorisation. But they were also eating correspondingly less, and that kept the obesity prevalence low,” Dr Sacks said.

“In many high income countries, a flipping point seems to have occurred in the 1970s with the still very sedentary population now eating more due to the ‘push effect’ of more readily available, cheaper, high-calorie foods.

“Obesity is increasing in all countries, but rates vary widely between countries. In Australia, around 1 in 4 adult woman are obese, compared to only 1 in 20 in Japan and China, 1 in 10 in The Netherlands, 1 in 3 in the USA, and a staggering 7 in 10 in Tonga. In some regions, such as Western Australia, obesity has overtaken tobacco as the largest preventable cause of disease.

“Obesity is now also sweeping through low-income and middle-income countries, threatening their development and leaving many countries with a double burden of obesity-related chronic disease in some people and malnourishment of others.”

Increased supply of cheap, tasty, energy-dense food, improved food distribution and more pervasive and persuasive food marketing are noted in The Lancet paper as the key drivers of the obesity epidemic.

“Obesity is the predictable result of people responding normally to these obesogenic environments,” Dr Sacks explained.

“Underlying all the main causes of obesity are the strong economic forces driving consumption and growth.

“While the policies that promote economic growth and free trade have many benefits, they are also contributing to the global crises of overconsumption, including both obesity and climate change.”

And while it might seem that reversing obesity is as simple as individuals taking charge of their own lives, the researchers point out that people have to negotiate a complex array of choices, with many decisions made subconsciously.

“The food industry is becoming ever more effective at promoting their products so that people are consuming excess energy without even realising it, so called ‘passive over-consumption’.”

The researchers believe that support for individuals to counteract obesogenic environments will continue to be important, but the priority should be for policies to reverse the obesogenic nature of these environments.

As UN Member States gather in New York for the first ever UN High-Level Meeting on non-communicable diseases in September, the researchers believe the inexorable global rise of obesity will be the toughest challenge that they face.

“The UN is calling for heads of state to make this meeting a priority, and there is an opportunity for Australia to take the lead in this area through strong government support for this issue,” Dr Sacks said.

The Lancet Series aims to state the case for action on obesity: what is the size and nature of the problem, what is driving its global increase, what will the future obesity burden be under a business-as-usual scenario, and what action is needed to reverse the epidemic?