KEY POINTS:
Insurance providers will continue using body mass indicator tests in calculating health insurance premiums - despite research suggesting the assessments are inaccurate and unfair.
Massey University researcher Steve Stannard said the BMI tests - which measure weight divided by the square of a person's height - should not be used to diagnose individuals' health status.
He believes BMI is accurate only when used to describe populations for statistical use and no good for individual cases.
But Investment, Savings and Insurance chief executive Vance Arkinstall said yesterday that the industry was likely to keep using the test despite the fact it could unfairly inflate people's insurance premiums.
He said the test was "one of a number of things" used by insurance providers to determine clients' risk. Other factors included whether the client smoked, had a "risky" job or bad heredity.
"All the insurance company is wanting to do is see if there is a particular or extra risk and how high that risk might be."
Dr Stannard's work on BMI was prompted when colleague Matthew Barnes was told he had to pay extra life insurance premiums because his BMI was 36. Mr Barnes' insurance company, ING, had rated him as obese even though blood-screening tests showed he was healthy.
ING rejected Mr Barnes' explanation that his high BMI was due to muscle mass from lifting weights, although it later reduced his premiums when Dr Stannard provided proof his body fat percentage indicated he was a healthy weight.
But Mr Arkinstall said many health professionals used the BMI test in patient assessments and the tests were "probably" accurate for most insurance customers.
Customers should not concerned about the test as it was in the companies' best interests to keep premiums down. "Life [insurance] companies are in the business of wanting to insure people. We are not in the business of making it difficult for people to get insurance," he said. "[Insurers] do have to make sure the premium is appropriate for the risk."
The Ministry of Health said it did not recommend the BMI tool for assessing obesity at an individual level.
It said BMI might be used as a screening tool by clinicians as a possible starting point for further investigation, based on discussions with the person.
Measuring waist circumference was a useful indicator of individual health risk from obesity. It was a better measure than waist-hip ratio (WHR) and BMI, being simpler and more convenient. It was also increasingly being used.
Waist circumference was unrelated to height, correlated closely with BMI and WHR and was an appropriate index of intra-abdominal fat mass and total body fat.
Also, changes in waist circumference reflected changes in risk factors for disease.
