KEY POINTS:
Around 15,000 New Zealand children are thought to be extremely obese, a new study has found.
The University of Otago study also finds marked ethnic differences in the rates of extreme childhood obesity, with one in ten Pacific Island children and one in twenty Maori children aged 5 to 14 likely to be extremely obese.
But only one in 100 European or other ethnicity child is likely to fall into that category.
Researcher Dr Ailsa Goulding said the findings were a "real worry" because young children do not necessarily look obese.
"Every parent wants a healthy child, [but] every parent does not recognise that their child is really big until it's really old ... These are in 5-year-olds even."
To reach their findings, researchers extrapolated data gathered from the Ministry of Health-funded National Children's Nutrition Survey, which took body mass index measurements of 3000 New Zealand children aged 5 to 14 years.
It showed a 2.7 per cent rate of extreme childhood obesity compared with 4 per cent in the United States. - but Pacific Island children stood out with a 10.9 per cent incidence of extreme obesity. Maori children had a 5.1 per cent incidence rate and New Zealand European children 0.8 per cent.
One of the few studies of its type in the world, it indicates that of the 576,900 New Zealand children in the 5 to 14-year age group at the time of survey, approximately 15,000 would be extremely obese.
Dr Goulding says the ethnic differences were substantial across all age and gender brackets. In Pacific Islanders, about one-third of the children classified as overweight were extremely obese - a higher proportion than the other two categories. The rate of extreme obesity for New Zealand European children was "better than expected", but many were still overweight or obese.
Dr Goulding said the study provided a strong case for more research into the underlying reasons for these ethnic disparities and ways to curb them.
