One third of New Zealand children is now reckoned to be overweight or obese.

Today, an expert on the issue says communities hold the key to changing that.

Auckland University's Dr Stefanie Vandevijvere is calling for action.

She says the problem in New Zealand is continuing to get worse.

"While in other countries, high income countries, they are flattening.

"Also like in France and the US are even decreasing a bit as well."

She says initiatives against obesity have until now been driven by health professionals...and believes communities have more power to prompt government action.