For 180 years, the Body Mass Index (BMI) has been the internationally preferred measurement standard in weight management and obesity healthcare.
Providing an indication of weight in relation to height, it became fully absorbed into the public's consciousness in the 1980s when obesity concerns were rising in the West - and yet in recent years, it has come under increasing fire from medical professionals for its inaccuracy.
Now a new global research project, the Body Benchmark Study, has been launched in London with an ambitious long-term aim to determine a more effective replacement - the Body Volume Index (BVI) - which will help more accurately predict the individual health risks associated with excess weight. The study is a collaboration between healthcare facilities, hospitals and professionals worldwide, and is being spearheaded by Select Research - a company specialising in body scanning research.
Over the next two years the aim is to record and measure the fat distribution, shape and volume of thousands of volunteers using a computer-linked 3D imaging scanner. These results will help benchmark BVI values for use in healthcare assessment over the next decade.
Project director Richard Barnes says data gathering is the "easy" part. "More complex will be determining the particular health risks associated with individual body shapes and other variables," he points out.
"Healthcare professionals need an indicator of the likelihood a patient has of developing insulin-resistance diabetes or cardiovascular disease, or of becoming anorexic or obese, for instance. BMI fails in this respect."
In fairness, BMI was designed solely as a broad indicator of body shape and not as a diagnostic or predictive tool. Taking only weight and height into account, its limitations are easily exposed: healthy muscular men and women are classified as "overweight"; pregnant and breastfeeding women are inappropriately scored; and accuracy levels slip as patients pass middle age. And there is no distinction between men and women, whose fat distribution patterns and associated health risks vary considerably.
BVI will consider much more than weight, height, shape and volume. Age, sex, ethnicity, medical and genetic history can be incorporated into the computerised calculation. "If a patient's ethnic background is known to be associated with a 10 per cent greater risk of type-II diabetes, for example, this can be factored in," says Barnes.
Pre-launch trials have suggested the technology has additional potential as a motivational tool. When patients embark on weight-loss programmes of healthy diets and exercise, body fat is replaced by lean muscle. But because fat weighs less than muscle, this positive effect is rarely noticed on the scales. "Seeing numerical results is a positive enforcement on dieters, and no change in weight or BMI is depressing," says clinical obesity specialist Dr Marjon Monfared.
"With BVI, on the other hand, scores will drop, and fat loss can be measured, recorded and shown. This is a huge motivational factor."
Those working in nutrition have welcomed the initiative too. "We know fat carried around the middle indicates a greater health risk for diabetes, heart disease, high cholesterol and high blood pressure than fat carried around the hips," says dietitian Dr Frankie Phillips. "This technology could allow dietitians to see precise fat distribution and associated health risks, and tailor a recommended dietary plan."
With European and worldwide involvement assured, there is eventual potential for a shared international database of medical information. The project directors are anticipating bringing on board Irish obesity clinics, hospitals and clinicians in the near future.