Weight measurement goes hi tech

BY JULIE SEAMER
THURSDAY, SEPTEMBER 27, 2007

Over the past 180 years or more, the body mass index (BMI) has been the most popular tool to define a healthy weight range. Under the BMI, using height and weight measurements, a person is categorised as underweight, normal, overweight or obese. This system is now believed to be outdated and flawed.

The Body Benchmark Study, launched in the UK recently, is claimed to be a more accurate and effective replacement. Unlike the one-size fits all technique of the BMI, the new Body Volume Index (BVI) is a scanner which measure weight in a more detailed way – taking into account body shape, muscle mass and the location of fat stored within the body.

Medical practitioners in Australia agree that healthcare assessment measures must improve. While the waist-to-hip ratio and waist circumference are powerful predictors of mortality-related heart disease and diabetes, the BVI is destined to take assessment much further than these tools and the BMI. Using a computer-linked 3-D body imaging scanner, the BVI can incorporate age, sex, ethnicity, medical history and generic risks into the calculation.

Dieticians have welcomed the initiative, and there are many reasons why. If a patient's ethnic background is known to be associated with a greater risk of diabetes, this can be factored in to their individual BVI assessment. The technology has added potential as a motivational tool. When patients embark on weight-loss programs, body fat is replaced by lean muscle. But fat weighs less than muscle which isn't represented on the scales. No change in weight or BMI can be depressing after dieting. However with the BVI, scores will drop and fat loss can be measured, recorded and shown.

Taking only weight and height into account is limiting. And for accuracy's sake, factors such as pregnancy, sex and breastfeeding need to be allowed for. Under the BMI, which doesn't take into consideration any of these factors, or fat and muscle distribution, Hollywood actors Brad Pitt and Russell Crowe are actually considered to be overweight! In fairness, the BMI is a broad indicator of body shape for public health purposes. And it was never designed to be a diagnostic tool.

Presented at a European Obesity Conference, the BVI is the focus of a two-year clinical study that has just begun. It is hoped that by the year 2009 walk-in BVI scanners will be widely available in the health industry.

Given that many of us are more likely to take heed of a computer reading than an individual with a measuring tape, telling us we're obese, the BVI promises great scope.