Weight measure BMI not always accurate: experts
IT IS the standard system used in surgeries and fitness centres all over the country to determine if a person needs to lose weight.
But according to some nutritionists and health experts, the Body Mass Index (BMI) scale is an often inaccurate and possibly dangerous estimation of what is healthy and what is not.
They say that the scale - worked out by dividing weight by height - can label certain people overweight, when in fact they have a normal amount of body fat. Sporty, strongly-built and muscled body types are highly likely to show up as having a BMI level that categorises them as being too heavy.
This is because BMI is worked out by dividing a person's weight in kilos by their height in centimetres squared.
A Body Mass Index of between 18.5 and 24.9 is regarded as healthy, a reading that comes in between 25 and 29 indicates someone is overweight, while a score of over 30 is obese and means the individual is obese and officially at greater risk of health disorders such as diabetes and heart disease.
Those who would have registered a score of below 18.5 are underweight, also leaving them in danger of serious health problems.
However, dietician Aveen Bannon of the Dublin Nutrition Centre said that she would not rely on the BMI scale as an indication of healthy weight.
Said Ms Bannon: "It is a nice, rough guide to a person's weight, but it can often be inaccurate.
"For example, a rugby player, who has a strong build made up of heavy muscle, will always have a high Body Mass Index and fall into the overweight category.
"But muscle weighs more than fat - so any weightlifter or bodybuilder will show a high BMI."
Furthermore, the dietician said that she has seen cases where a person has a low BMI, but in fact needs to lose some body fat.
Health and nutrition consultant Kathy Fulcher is also wary of relying on the scale.
"For some typically stocky people, achieving a low BMI is unrealistic," she explained. "Even if they reduce their body fat right down, they still won't drop into the low category.
"So I just advise some clients to ignore it, forget about it. BMI certainly does not work for everyone."
A study published by the American Journal of Epidemiology found that BMI did not predict heart attack risk in those over 70.
Experts now say that a better way of assessing the risk of cardiovascular problems is the tape measure - a waist of more than 35 inches for a woman and 40 inches for a man is a danger.
They believe that a person with a waist this size will have an excess of the most dangerous form of fat, visceral fat.
Visceral fat is stored in the abdomen around the major organs and is far more active than fat stored under the skin. When the store gets too large, it begins to pump out inflammatory and clot-producing compounds.
The unreliability of the BMI scale could also be hazardous to the health of those prone to eating disorders.
Gerry Campion of Dublin's Marino Therapy Clinic said that BMI scale results can be dangerous to people who focus on every little detail of their weight and body shape.
He described the scale as "a sweeping statement, a massive generalisation" that does not work for the overall population.
He said that many fit athletes with heavy-set frames have high BMIs, obese levels, when in fact they are extremely healthy.
"It can be taken out of context - sometimes a person who is a perfectly healthy size will have a BMI that puts them into the overweight category.
"Some people may never have a low BMI rate, no matter how slim they are, as it is just their build.
"So there are some people whose BMI is higher than they'd like and it can set off alarm bells."
