A global study of five- to 19-year-olds has found Kiwi kids rank amongst the most unhealthy across 200 countries and territories.
The Science Media Exchange study compared 65 million school-aged children, pooling data from 2181 population-based studies over 34 year period - 1985 to 2019.
Researchers found Pacific Island kids had the highest BMI in the world in 2019, with New Zealand not far behind.
Someone's BMI is a measure of the proportion of body fat to total body weight, and it is calculated using a person's weight and height.
Elaine Rush, professor emeritus of nutrition at Auckland University of Technology, said an increasing BMI is usually associated with poverty, food insecurity and is higher in Māori and Pacific children.
"It is true that between 1985 and 2019, New Zealand has an unacceptably high and increasing prevalence of excess body weight and rapid growth in our tamariki," she said.
"A greater proportion of Māori and Pacific children live in areas of deprivation than European and Asian children. This is recorded in the annual reports of the New Zealand Health Survey."
University of Auckland's Collin Tukuitonga, who is the associate dean of Pacific studies and associate professor of public health, added that a number of unhealthy trends were reported in the survey, including that Pacific Island boys and those from New Zealand were among those gaining too much weight for height.
However, he said the study confirmed much of what was already known - that BMI was highest in 19-year-old Pacific Island boys, often surpassing 28kg/m2.
"Study findings have important implications for nutrition policies in NZ and the Pacific Islands, including considerations for agriculture and food policies."
Authors of the international study said more investment is needed for school-aged kids and teenagers, including free healthy school meals and better sports facilities.