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New measure for fatness

Jul 22, 2007 7:07 PM

If you have ever used a heigh weight chart you are probably familiar with the BMI - body mass index.

It is basically an estimate of how overweight you are.

But the statistics are based on data gathered from Americans, so Massey University researchers are developing a measure based on Kiwi bodies.

"The best way, the gold standard in scientific terms, is underwater weighing," says Chris Cunningham, from Massey University.

Cunningham is dunking healthy Kiwis so he can work out new ways of estimating how fat they are.

"The norms that we have might not be applicable to Maori and Pacific or Asian people, so what we're doing here is to measure a whole lot of people and try to work out what these New Zealand norms are," Cunningham says.

That is because the measure used by many in the health and insurance industry - the BMI - is considered flawed because it's based on American bodies.

"It doesn't actually indicate where the fat's distributed, it just gives you a broad range," says Nalisha Patel, a personal trainer.

It's a broad range that can often see you wrong.

Bodybuilder Matt Barnes got charged higher insurance premiums because the charts said he was obese, even though his body fat was minimal.

"They looked at charging us an extra 50% on top of the premiums," says Barnes.

The insurance industry says it does its best with the tools it has.

"It gives us an indication of a possibility of an increased risk," says David Drillien, from Sovereign Insurance.

"The shortfalls is, it's not an absolute. We do need to look at other things besides BMI."

When the researchers are finished they hope to have a more accurate tool to determine healthy weights for Kiwis

But until then, there is an easy shortcut to know if you are fit or fat - and you don't even need a calculator, just take a tape measure and wrap it round your middle.

"For men you ultimately want to be less than 102cm and for females it's less than 88cm. Thats the ideal range to be healthy," says Patel.