More than 7 million Australians aged 25 and over are considered overweight and, of these, more than 2 million are obese, according to the Australian Institute of Health and Welfare. The director of the Institute of Health Economics and Technology assessment, Paul Gross, said as the obesity epidemic rose, Australians were more likely to seek help losing weight. "When we get to levels of desperation … all sorts of options that were seen as too expensive or time-consuming are suddenly considered," Dr Gross said.

Despite being weight conscious, Australians were relaxed when it came to weighing themselves, with 38 per cent likely to hop on the scales only when they remembered, and one in five not weighing themselves at all, according to the survey, conducted in 13 countries including Hong Kong, Singapore, Malaysia, Canada, Saudi Arabia and Brazil.

Dr Gross said about half of overweight or obese people considered their weight ideal. "If you want to deny something don't measure it," said Dr Gross, who has called for the amount of exercise school children take to be recorded on school reports. "Parents who are overweight are less likely to think their children are too."

Throughout the world, about 1.6 billion people aged 15 and over are overweight and at least 400 million are obese, the World Health Organisation says. Those figures are expected to rise to about 2.3 billion adults overweight and more than 700 million obese by 2015.

The survey, by the global marketing company Synovate, revealed conflicting attitudes to healthy eating in the countries surveyed.

More than half of all respondents (54 per cent) said they ate whatever they wanted, whenever they wanted. However, more than two thirds (68 per cent) said they watched their food intake carefully and tried to be healthy.

Most Australians believed obesity was caused by an unhealthy diet, followed by a lack of exercise and self-discipline.