A problem of perception: Kiwis don't think they are as fat as they really are.

Kiwis are porky and dangerously deluded about it, a new study has found.

While we might tout ourselves as a sports-mad nation, the reality is most of us are hopelessly inactive.

According to a study comparing 11 countries, Kiwis were not only the chubbiest, but were "wildly off the mark" in estimating how fat they were.

STUFF Research has shown Kiwi parents consider their normal-weight children underweight, and consider overweight children to be healthy.

While six in 10 were overweight or obese, most thought only 45 per cent of us fitted that description, independent research for the annual Cigna 360° Wellbeing Score found.

Health and nutrition experts are not surprised. "I think it's normal to be overweight now," New Zealand Nutrition Foundation dietitian Sarah Hanrahan said.

"More than half the population is overweight. You will see more overweight than you will see within the normal weight range, and in some parts of town it will be even more than that."

University of Otago professor in human nutrition and medicine Jim Mann said that, in general, people underestimated how many of their peers were overweight and obese.

"We know from proper scientific research that people underestimate obesity in children because we've got so used to seeing children who are fat."

New Zealand researchers found parents tended to think of normal-weight children as underweight, and overweight children as normal, he said.

People tended to underestimate their own weights as well, Edgar National Centre for Diabetes and Obesity Research associate professor Rachael Taylor said.

"People are also not comfortable using some of the terminology. "Obese", for instance, is seen by many as very, very discriminatory. People tend to equate that word with morbid obesity."

She pointed out that a woman about 1.67m (5ft 5½in) tall who weighed 86 kilograms would be medically classed as obese, but not by their peers.

"The majority of adults would probably refer to this as overweight, but not obese per se."

And while we may be a country of sports fans, the score indicated our sports are better enjoyed from the couch than the field.

More than half of Kiwis enjoyed watching rugby on television, but only 4 per cent actually played.

Furthermore, those surveyed who reported enjoying watching rugby were statistically fatter than the average person. "That maybe says something about our perception of ourselves as sports loving people," Hanrahan said.

"We might be sports-loving people but are we sports-playing people? And more importantly, are we active?

"I can well imagine if you list one of your hobbies as watching rugby, it could well correlate with being overweight."

The answer was moving more – not necessarily just playing sport – and eating better, she said. People had to be eating and exercising better than "normal" to be a healthy weight.

"If it were easy to lose weight, everybody would be doing it.

"It's now the norm to be overweight, so it's harder to do something about it. If that's the normal response to your environment, you have to do something quite different to not be overweight."

BY THE NUMBERS

* Almost seven out of 10 Kiwis want to lose weight.

* But about a third aren't doing more than 30 minutes of exercise a week.

* While almost seven out of 10 of us are overweight or obese, most Kiwis would say just under half of the population were fat.

* About seven in 10 rugby fans are overweight or obese.

* A peek into our fridges finds one in three Kiwis have sugary drinks in there. Almost the same proportion have booze.

SAMPLE SIZE

The figures are from the annual Cigna 360° Wellbeing Score survey, with a sample size of 1000 New Zealanders, 50/50 male/female, various ages from 25+. The survey was conducted by Ipsos market researchers.