Each year, around 2.8 million people die as a result of being overweight or obese, say international health experts.
Globalisation has brought fast food culture to Chinese cities, contributing to major obesity problems. A study in 2006 found that over one-fifth of the one billion obese or overweight people in the world are Chinese, Xinhua reported.
One of the fattest nations in the developed world, Australia also shares this obesity problem. If Australians' weight gain continues at current levels, almost 80 percent of adults will be overweight or obese by 2025, according to Monash University.
To discuss the problem of obesity and evaluate a solution being developed by the Public Health Association of Australia, international nutrition experts met at an obesity and nutrition conference in Sydney.
The rise of multinational fast food outlets has been a key change in our environment leading to fatter foods and fatter people, said Bruce Neal, professor at the George Institute for Global Health in Sydney.
"As fast as we get rid of all our traditional vectors of disease -- infections, little microbes, bugs -- we are replacing them with the new vectors of disease, which are massive transnational, national, multinational corporations selling vast amounts of salt, fat and sugar," Neal said.
Over time, consumers in developed countries have become acculturated to larger serving sizes that are well above what's necessary for an enjoyable, sensible and nutritious meal, said Tim Gill, associate professor at the University of Sydney's Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders.
"People will consume a portion that's put in front of them. People will seek value by purchasing the largest portion size, because it's relatively cheap compared to the smaller size. We've just had a disconnect in terms of what we need to eat and what we can purchase," he said.
A 2005 study by American scientists found that diners who ate from a bowl of soup that kept refilling would not only eat far more than normal, but they did not notice that they had eaten more, and did not feel more sated.
Most shoppers base their food choices on price rather than nutritional value, with lower socio-economic status consumers more likely to eat high energy-dense foods such as sugary drinks, said Marion Hetherington, a professor of biopsychology at the University of Leeds.
However, Jennie Brand-Miller, a professor at the University of Sydney's School of Molecular Bioscience, said low-fat diets may not in fact be best for our health.
"Low-fat dietary advice has not been helpful on a population level. It is consistently associated with weight regain. It does not reduce the risk of chronic disease," said Brand-Miller.
"We need to pay more importance to protein. Protein is satiating, and we've undervalued it. We need to pay more attention to the sources of carbohydrate -- we need to switch from high GI to low GI carbohydrates," she said.
At the heart of the obesity issue is the question of responsibility, and whether it's up to the consumers to look after their own needs, or industry to provide more healthy foods.
"In Britain, the public health responsibility has been an important initiative in the sense that companies will sign up, they will pledge to reduce the amount of calories in their food, to reduce the amount of salt," said Hetherington.
By lowering salt, sugar and calorie content of their foods independently, industry will not face competitive pressure caused by only some producers providing more healthy foods in the marketplace, she said.