An intensive DNA search will seek the specific genetic causes of obesity and Type-2 diabetes in New Zealanders.

Up to 500 genes could be conspiring to make Kiwis susceptible to obesity and Type-2 diabetes.

A new research project will take the closest look ever at New Zealanders' DNA, examining 500 places on our genetic code where appetite and energy metabolism were thought to be controlled.

Previously, international scientists had suggested a number of genes were linked to the diseases, flagged as responsible for a growing worldwide health crisis.

But study co-director Peter Shepherd said there was no reason to assume the same genes behind obesity in the United States or Japan, for example, were at fault over here.

"It's not going to be one gene, this is going to be the additive effects of different genes that will ultimately be the answer. In different parts of the world, it's apparent that different combinations of these are more or less important."

The University of Auckland professor said New Zealand's unique mixture of eastern and western European, Maori, Polynesian and Asian ancestries was likely to yield a different genetic pattern from other countries. "The more information we can get about the New Zealand population the better."

The new $1 million Maurice Wilkins Centre study, announced on Tuesday at Queenstown Research Week, would also take a close-up look at the DNA in Kiwi diabetes and obesity sufferers. Previous research had taken a much broader view, he said. "It's a bit like how the oil industry scans across the ocean bed to find areas where there might be oil, and the most likely places to look.

"What we're doing is using some of that information to drill down, to zero in on the exact genes in that area and the exact mutations that are causing the problem. It's only from understanding it from that level that we'll be able to understand the biology around it."

Shepherd said two major benefits would come of out the study, which would sequence the DNA of 600 New Zealanders. The first was that a person's DNA could be used to understand what factors – from a low metabolism to the body's failure to correctly signal it was full – might be behind their individual struggles with weight.

"What we hope to do is use this information to inform dietary intervention strategies ... and come up with some practical solutions in the short term."

The second benefit would be helping the public understand biology played a large – though not a complete – role in causing people to be obese or to develop Type-2 diabetes, he said. "It's very important for people to understand that there are biological factors that contribute to weight. A lot of people, you might even say, are prejudiced against people because of their weight."

Initial results are expected next year.