Tragedy ... Australians face being part of the first-ever generation who will live shorter lives than their parents. Source: Supplied

Yet, for Australians, the stakes are even higher, Professor Stephen Colagiuri, who works at Sydney’s Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, says.

“The situation’s even worse for us than this study reports because it’s limited in what it looks at — the issue is broader than what they look at,” he told News Corp Australia.

The study, published in The Lancet Diabetes & Endocrinology Journal, looked at the effects of diabetes and cardiovascular disease on adults.

The researchers, led by lead author and Professor of Medicine at McGill University, Steven Grover, built a computer model that measured the increased risk of developing cardiovascular disease and diabetes in adults of varying body weight.

TRAGIC END: World’s heaviest man in the world dies

Health costs ... about 65 per cent of all Australian adults are overweight or obese. Picture: Thinkstock Source: ThinkStock

What they found was frightening: not only did the researchers quantify the shortening of life, they were able to relate it to bands of body weight that showed a direct correlation between an individual’s weight and the number of life years they stood to lose.

Professor Grover’s team also found that obesity and extreme obesity — which can result in type 2 diabetes, cardiovascular disease and many more health problems — can also deprive adults of nearly two decades of healthy living.

“Our computer modelling study shows that obesity is associated with an increased risk of developing cardiovascular disease (including heart disease and stroke) and diabetes that will, on average, dramatically reduce an individual’s life expectancy and the healthy life-years free from living with these chronic illnesses compared with people of normal weight,” Dr Steven Grover explained.

The results? People with a body mass index (BMI) between 25 and 30 — classified as overweight — could lose up to three years off their life expectancy, depending on their age and gender.

More risks ... being obese at a younger age can lead to developing it in adulthood, researchers say. Picture: Supplied Source: Supplied

Those whose BMI was between 30 and 35 could die up to six years earlier, and adults who were very obese — BMI index of 35 and over — could lose as much as eight years.

And being obese at a younger age is more risky than developing obesity in adult hood.

“The more an individual weighs and the younger their age, the greater the effect on their health, as they have many years ahead of them during which the increased health risks associated with obesity can negatively impact their lives.”

But Professor Colagiuri said while the study’s quantifying methods were “useful” in also focusing on the quality, rather than just the length, of life, the study did not take “other problems, such arthritis, mental health problems, sleep apnoea and more” under consideration.

“All those things are increased when one is obese — the situations even worse that this study reports,” Professor Colagiuri said.

He said that white the research was based on US data, “our situation with regard to the number of people who are obese and severely obese is just as bad”.

“For us [Australians] about 65 per cent adults over the age of 18 are overweight or obese, and out of those, about 20 to 25 per cent are severely obese,” he said.

Australian children fare better, but only just. Kathy Chapman, the Cancer Council’s director of Cancer Programs and Chair of the Nutrition Committee, said that obesity in children has only recently stabilised after years of blowing out.

“Although one out of four children are overweight or obese, it looks like it’s starting to plateau at 23 per cent,” Ms Chapman told News Corp Australia.

“In the 80s, 90s, 2000s, we were seeing it go up ... [but] we’re starting to realise it’s a problem.”

Adults, however, were on a slippery slope, with more than 65 per cent of Australian adults suffering from obesity.

“It’s certainly good news about children, but in adults it’s a huge problem,” she said,

“We have to reverse this trend — the younger you can prevent it, the more likely it is to stay off.”

Binge eater ... Keith Martin consumed on average 20,000 calories a day. Picture: Channel Five Source: Supplied

Ms Chapman agreed about the study’s modelling: “It’s really good when you have modelling to see the impact it’s having — we know it’s a risk factor for cancer, heart diseases etc, and this is putting a number on what a huge impact it is”.

“If we don’t do something soon, this could be the first time we have a generation that dies at a younger age level than their parents.”

The study comes just before the death of British national 44-year-old Keith Martin, who, at 445 kilograms, was the heaviest man in the world.