He said one of the "most frightening" parts of the data was looking at the distribution curve and the way it had shifted towards more children being overweight.
"This is about the environment all children experience."
He said about one in four fell into the general overweight or obese category. About one in 10 were obese. "A great proportion are now overweight or obese."
Research showed children who were overweight and obese were more likely to be overweight or obese adults.
He said childhood obesity was a major focus and a local action group had been formed including representatives from public health, paediatricians, representatives from the council and other organisations.
It was about recognising the ability to work together, he said.
Dr de Wet said he believed the biggest change needed to come by changing the risk factors that affected all children - especially the food environment.
While they could, and did, work with individuals Dr de Wet said the situation would never really change until the wider picture changed. "The key focus has to be on the range of strategies that improve children's diet."
He said a real focus was on reducing the consumption of sugary drinks especially in places children learnt and played. He said sugary drinks were a focus because they provided so little nutritional benefits and contained so much sugar.
"We have got to look at how we make healthy food more easily available and accessible. The key issue is not so much about how much we eat, it's about what we eat."
Dr de Wet said many of the problems stemmed back to the fact that people were consuming a lot more sugar on average than they needed to. "We should be thinking of this problem not so much as an obesity epidemic as a sugar epidemic."
Healthy Families New Zealand Rotorua manager Leanne Morehu said the obesity challenge was high on its priority list.
She said a lot of it had to do with the environment children lived in, as well as the messaging in advertising.
Children drinking too many sugar sweetened beverages and not eating enough fruit and vegetables were both problems, she said. Seventeen per cent of all children had fizzy drink three or more times a week in New Zealand, Mrs Morehu said.
She said the situation was a crisis, and according to the Organisation for Economic Co-operation and Development, New Zealand was the third most obese nation in the OECD. The organisation had been working with others to set up a local food network so people in the community could have better access to fresh fruit and vegetables which were affordable, she said. Mrs Morehu said the organisation had also challenged people to drink only water throughout April, having started in the eastside community, to raise the harm of sugar sweetened beverages. She said all sorts of platforms were being used to try to get the message across, including school presentations. Additional reporting by Shauni James
